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AGRICULTURE HANDBOOK NO. 252 • U.S. DEPARTMENT OF AGRICULTURE • FOREST SERVICE
WOOD CRATE

Design Manual

By L. O. ANDERSON, Engineer, and T. B. HEEBINK, Engineer

FOREST PRODUCTS LABORATORY

(Maintained at Madison, Wis., in

cooperation with the University of

Wisconsin)

AGRICULTURE HANDBOOK NO. 252 FEBRUARY 1964

FOREST SERVICE . U.S. DEPARTMENT OF AGRICULTURE

For sale by the Superintendent of Documents, U.S. Government Printing Office

Washington, D.C., 20402 - Price 70 cents
CONTENTS

Page

Introduction 1

Factors that affect crate design 2

Contents 2

Destination and method of transit 2

Handling hazards 2

Storage conditions 4

Costs 4

Materials for crates 5

Wood and wood-base materials 5

Fastenings 13

Designing crates 23

Importance of diagonals 24

Design principles 24

Designing the crate base 29

Designing the top 31

Sheathed crates 32

Military type sheathed crates 32

Limited-military sheathed crates 45

Light-duty sheathed crates 46

Open crates 50

Military type open crates 50

Limited-military type open crates 53

Page

Light-duty open crates 59

Skid assemblies 68

Skid sizes 68

Floorboard sizes 73

Diagonal bracing 73

Assembly 73

Testing crates 73

Superimposed-load tests 74

Handling tests 76

Drop and impact tests 78

Appendix I. Panel member sizes 80

Appendix IL Details of shipping 120

Marking 120

Packing lists 120

Shipping loss prevention 121

Export shipping 121

Anchoring crates to ship surfaces 121

Carloading crates 121

Shipping losses and insurance 123

Tare weight of crates 123

Appendix III. Glossary 125

Index 129

ACKNOWLEDGMENT

In preparing this pubUcation, the authors have been privileged to draw on

much of the research of the late C. A. Plaskett, the late T. A. Carlson, and

H. J. Knelling, as well as a number of other members of the Forest Products

Laboratory and various Defense Agencies. The number of these contributors

is so great that individual acknowledgment is impractical.

n
INTRODUCTION

The packaging industry consumes 15 to 20

percent of each year's timber cut, in the form of

lumber, plywood, veneer, container fiberboard,

composite materials such as paper overlaid veneer,

and papers of various types. Because of this

continued heavy use of wood, the Forest Products

Laboratory, U.S. Forest Ser\âce, has always devoted much research to packaging. Much of this

research has been conducted over the years in

cooperation with the Air Force, the Army Corps

of Engineers and Ordnance Corps, other agencies

of the Defense Department, and several industrial

firms.

Of principal concern are the fundamental principles of design and the relationships of various

details in the construction of containers that are

balanced in strength. Special testing machines

and methods of testing have been developed.

From this research, supplemented by study and

observation of shipping containers in service, has

come much information of value to packaging

engineers.

The growth of American industry has generated

great needs for containers of all kinds, from colorful wraps for retail merchandise to workhorse

containers for the worldwide shipment of machines

and equipment of any size, shape, and weight.

Among these containers, the wood crate is one of

the most important used for shipping and is perhaps the most adaptable to the apphcation of

engineering principles in design. Crates are generally made of wood (or a wood-base material)

because it is strong and rigid, comparatively light

in weight, inexpensive, easily formed into a multitude of sizes and designs, and adaptable to a

variety of conditions of use.

A wood crate is a structural framework of

members fastened together to form a rigid enclosure, which will protect the contents during

shipping and storage. This enclosure is usually of

rectangular outline and may or may not be

sheathed. A crate differs from a nailed wood box

m that the framework of members in sides and

ends provides the basic strength (fig. 1), whereas

a box must rely for its strength solely on the boards

of the sides, ends, top, and bottom. This framework can be considered to be similar to a type of

truss used in bridge construction. It is designed

to^ absorb most of the stresses imposed by handling and stacking.

Notable among the findings and developments

of the Forest Products Laboratory is the evolution

Figure 1.—Typical open crate.

of crate design criteria for virtually any type of

machine or other industrial product. These

criteria are based on the following considerations:

1. A crate must be strong enough to protect its

contents from the hazards of shipping and storage.

2. The lumber and other materials used to build

the crate must be of suitable quality and dimensions.

3. A crate must be as light in weight as shipping

hazards and the inherent strength properties of

the materials permit.

4. It must require a minimum of shipping space.

With design criteria based on these considerations, the effective engineering of crates for specific

purposes becomes possible. This handbook presents information of a general nature applicable to

the design of most types of crates and the solution

of crating problems. It is not intended to be a

specification; however, in order to clarify design

and construction of crates, a number of crate

designs are included to aid the designer in his

specific problem. It includes all data required for

the design of crates, such as allowable working

stresses for the various species of wood and the

method of determining fastening requirements.

The advantages gained from good crate design

are many. The shipper gains from better protection of his products and from lower shipping costs

for lighter weight and lower space requirements.

The carrier gains from lower liability costs. The

consumer gains from the lower prices made possible for the goods shipped, and the Nation benefits

from the eflRcient use of raw materials.
FACTORS THAT AFFECT CRATE DESIGN

The selection of a crate depends on, in general

order of importance, contents, destination, method

of transit, handling hazards, storage conditions,

and costs. These factors overlap, but each will be

outlined separately to aid the designer or sliipper

in selecting the proper crate.

CONTENTS

The nature of the item being crated is of fundamental importance in the selection of a shipping

crate. If the item is ruggedl}^ constructed, such

as an axle assembly for a large truck, it has probabl}^ been prepared to resist the weather. Hence,

an open crate would be more economical for this

use than a closed one. While such an item could

withstand a considerable amount of handling

without damage, it would be easier to handle and

store if it were crated.

Items less rugged or requiring protection from

the weather would be shipped in fully sheathed

crates. In all cases, however, the crate must be

sturdy enough to (1) provide ample anchorage for

the item, (2) resist rough handling, and (3) withstand superimposed loads.

Disassembly or partial disassembly often allows

the use of smaller crates. However, the shipper

should consider the reassembly necessary at destination. If he is shipping to his own distributor,

the cost of reassembly can be compared with the

savings made by the use of smaller crates. Unless

the customer or distributor is equipped and willing

to reassemble, it may be wise to ship the article

completely assembled.

The type of base with which the item is equipped

should also be considered. Certain items may be

adaptable to the use of a crate with a sill-type

base, but the majority are best suited to a skidtype base. The latter include equipment having

a flat base with a distributed load or a base of the

leg, single or double column, end frame, or pedestal

type.

DESTINATION AND METHOD OF

TRANSIT

The destination often automatically determines

the style of crate. In surface shipment overseas

the crate might either be placed in the hold of a

ship or on the deck. For easy passage of a crate

through the average hatchway and into the hold,

the outside dimensions should not exceed 41 feet

in length, 9 feet in width, and 7 feet in height.

Any crate larger than this will likely be placed on

the deck. A sheathed crate with a waterproof

top is advisable for shipment on deck. Since

smaller crates are not always placed in the hold,

it would be logical to select a sheathed crate for

most items that are destined for foreign ports.

Ordinarily there is a maximum size for rail

shipment. This limit is to assure proper clearance

of crates on a flatcar going through tunnels, under

bridges, and around curves. However, size limitations may change, and a thorough check should

be made with the transportation agencies involved

before unusually large crates are shipped.

Consider if trucks may be used for short- or

long-distance hauling. For truck transportation

within the country only a basic framework may

be needed to conveniently handle the item.

Shipment of material by airfreight is becoming

more practical for certain high-value items.

Because these are usually of smaU or moderate

size and receive preferential handling, they require

only a light crate or a skid base.

To design a crate capable of resisting the most

severe of the many hazards to be encountered in

transit would ordinarily result in overdesign. It

would be costly, and justifiable only on rare occasions. However, a general idea of transit conditions will usually convince the shipper that none

of the generally accepted principles of crate design

should be overlooked.

HANDLING HAZARDS

Crates may be handled in a variety of ways,

but the most important from the standpoint of

design are end slinging, forklift handling, and

grabhook lifting. Unless provisions are made for

these types of handling, damage simUar to that

caused by the grabhook in figure 2 will likely

occur.

Other stresses are placed on crates during shipment. Crates may be moved by pushing or

skidding. Humping of freight cars can place

racking stresses on crates and cause failure similar

to that shown in figure 3 unless crates are designed and constructed properly. The vibration

of railroad cars may cause faüure of fastenings

or loosening of blocking and bracing. Transportation by motor truck also involves more

shipping hazards than are apparent. Loads are

often not secured to the truck bed, and containers

are subjected to vertical movements. End or

side impacts and accidental dropping of one end

of the crate are other hazards during handling

that must be considered.
WOOD CRATE DESIGN MANUAL

The crushing stresses of slings or grabhooks

are resisted by the joists or other members in the

top. Racking stresses from end thrusts or

humping are resisted by the diagonals in lumbersheathed crates and by the plywood in plywoodsheathed crates. Correct nailing of the crate

panels as they are fabricated and using enough

fastemngs in assembling panels into a crate will

further msure adequate strength to resist vibration and other stresses.

The handling of crates in foreign ports usually

depends largely on the mechanical equipment

available for unloading. Crates are often placed

aboard small lighters with the ship's gear and

unloaded at the dock site by a variety of methods.

The crate designer should consider a design with

a larger factor of safety to allow for such additional hazards.

Figure 2.—Crate damage caused by a grabhook when there was

insufficient joist support in the top of the crate.

rrgure 3. Failure of crate on railway car. Crate did not have racking resistance or the capacity to carry top loads under these shipping

conditions.
AGRICULTURE HANDBOOK 25 2, U.S. DEPT. OF AGRICULTURE

STORAGE CONDITIONS

A crate that will be transported in a covered

carrier and either unpacked immediately upon

arrival or placed in a warehouse does not require

sheathing for protection, and an open crate might

be selected. If the shipment is stored outdoors

or exposed for a long time to the weather, the

sheathed crate is a logical selection.

All crates, open or sheathed, should be capable

of withstanding top loads. When top loading

of crates is not considered in design, failure or

excessive deflection may occur and result in

damaged contents. Under most conditions, crates

of like size and contents will be placed one atop

another in warehouse or outdoor storage. This

is called like-on-like stacking. The sides and ends

of the lower crates support the load, and little

stress is carried by the top panel. For this

reason it is logical to reduce the requirements for

tops of sheathed crates. Crate tops are stressed

when smaller containers are superimposed. Only

like-on-like stacking is considered with open

crates. They are usually not designed for top

loading with, smaller containers.

COSTS

The selection of the proper type of crate may

gain a saving in both construction and shipping

costs. An open crate costs less than a sheathed

crate. It generally involves less material, lower

construction costs, and a lower shipping cost

because of less weight and cubic displacement.

The amount of lumber saved by using open

crates rather than fully sheathed crates varies

somewhat with the type of crate selected. For

light and medium loads, the open crate uses a

minimum of material and the saving is substantial.

For heavy loads, the open crate uses proportionately more material and the saving is less.

The nailed style open crate for hea\^ items requires the use of sheathing to provide fastening

areas for assembly nailmg to the base. This style

is similar to a lumber-sheathed crate with some of

the sheathing boards eliminated. The main

saving of lumber in an open crate compared with

a fully sheathed crate results from (a) the reduction of sheathing in top, sides, and ends; (b) the

elimmation of joists except the lifting joist; and

(c) the elimination of most of the covering material

except diagonals for the base and crosspieces.

The saving of material possible by using open

crates was further illustrated at the Forest Products Laboratory by the construction and testing

of 11 large open, bolted crates carrying net loads

of from 2,600 to 24,700 pounds. The average

saving of lumber compared with fully sheathed

crates was 12 percent in the bases, 47 percent in

the sides, 49 percent in the ends, and 58 percent

in the tops, or 40 percent for the entire crate.

The greatest saving was in the smaller, light

crates. In the nailed, open style for heavy loads,

the saving averaged about 30 percent compared

with a fully sheathed crate designed for the same

load.

A plywood-sheathed crate often costs less than

a lumber-sheathed crate. The difference in cost

depends largely on the comparative prices of plywood and lumber sheathing. vSince a plywoodsheathed crate does not require diagonals, the

material and installation costs of diagonals may

be weighed against the additional cost of the plywood. The lower tare weight and cubic displacement with plywood also should be considered.

To further reduce cost, the cubic displacement

and weight of the crate and contents must be

considered. Even in domestic shipment any reductions in these are important to the crate

designer. The cost of shipping crates by truck or

rail is generally based on weight, although large,

bulky items have higher rates than smaller but

heavier ones.

Air shipment of critical items is becoming more

practical, and large, odd-shaped items require

some type of container for blocking and mechanical protection. Here careful analysis and design

are necessary to provide sufficient strength without

excessive crate weight.

Export vessel shipping rates are usually based

upon a ton (generally 2,240 pounds but sometimes 2,000 pounds) or on 40 cubic feet, whichever

produces the greater tariff. As an average, this

means that unless the crate and contents weigh

more than 56 pounds per cubic foot (2,240 divided

by 40) the volume rate applies. Inasmuch as

most material shipped has a density much under

this figure, decreasing the cubic displacement of a

crate becomes very important. Crates with unnecessarily large clearances have greater volumes,

which mean higher costs. A crate that weighs only

28 pounds per cubic foot will cost twice as much

in freight per pound as the same size crate that

weighs 56 pounds per cubic foot. The cubic displacement of a crate 100 inches long, 40 inches

wide, and 50 inches high is about 116 cubic

feet. By decreasing the measurements only an

inch in each dimension, the displacement would

be reduced to about 109 cubic feet, or a saving of

6 percent.
MATERIALS FOR CRATES

The most important materials used in constructing crates are wood in its various forms and

the fasteners used for fabrication and assembly.

Sound crate design criteria and proper use of materials will result in a crate that combines maximum strength with minimum materials.

WOOD AND WOOD-BASE MATERIALS

Species

The species of wood most commonly used in

crate construction are divided into four groups,

largely on the basis of density. In general, it is

good practice to use species in the same group for

similar parts.

GROUP I.^softer woods of both the coniferous

(softwood) and the broad-leaved (hardwood)

species. These woods do not split readily when

nailed and have moderate nail-holding capacity,

moderate strength as a beam, and moderate capacity to resist shock. They are soft, light in

weight, easy to work, hold their shape well after

manufacture, and usually are easy to dry.

aspen (popple) magnolia

basswood pine (except southern

buckeye yellow)

cedars redwood

chestnut spruces

cottonwood willow

cypress yellow-poplar

firs (true)

GROUP II.—heavier coniferous woods. These

woods usually have a pronounced contrast in the

hardness of the springwood and the summerwood. They have greater nail-holding capacity

than the group I woods, but are more inclined to

split. The hard summerwood bands often deflect

nails and cause them to run out at the side of

the piece.

Douglas-fir tamarack

hemlock western larch

southern yellow pine

GROUP III.—hardwoods of medium density.

These woods have about the same nail-holding

capacity and strength as a beam as the group II

woods, but are less inclined to split and shatter.

ash (except white) sweetgum

soft elm sycamore

soft maple túpelo

GROUP IV.—heavy hardwood species, the heaviest and hardest domestic woods. They have the

greatest capacity both to resist shock and hold

nails. They are often desirable for load-bearing

members, skids, or joists. They are difficult to

nail and tend to split when nailed, but are especially useful where high nail-holding capacity is

required.

beech hard maple pecan

birch hickory rock elm

hackberry oaks white ash

Strength and variability,—In any species, a wide

range in strength and other properties exists in

lumber as it is sawed. However, average values

have been established for most native species of

wood.^ Since these values were obtained from

small, clear specimens, a number of factors must

be applied to arrive at stress values suitable for

the design of crates. Table 1 shows the variations

in these values among species that might be used

for crates. It lists not only the densities and the

shrinkages from green to ovendry condition, but

also such properties as static and impact bending

strength, maximum crushing strength, and hardness. Designers using these values must recognize

that they are averages for each species. Wide

variations are possible in individual pieces of

lumber.

Weight.—The unit weight or density of wood is

an important consideration in selecting lumber

for a particular use (table 1). Weight per cubic

foot not only directly influences the cost of

handling and transportation, but it also is a

relatively good measure of strength and resistance

to nail withdrawal. And it roughly indicates the

amount of shrinking and warping likely to occm*

with changes in moisture content. Dense woods

are outstanding where high resistance to nail

withdrawal is important, but they must be more

carefully nailed to prevent splitting and generally

they shrink more than softer, lighter woods.

As a rule, the lighter woods give less trouble in

seasoning, manufacture, and storage of lumber,

shook, or completed containers.

The weight of dry lumber per thousand board

feet varies from about 1,800 pounds for very light

species to over 4,000 pounds for very heavy

species. A definite way of expressing the weight

of wood at a given moistvire content is in pounds

per cubic foot or per square foot of a specified

thickness.

In the same species of wood the weight of

lumber varies considerably because of differences

in density. Variations exist even within wood

from the same tree. For example, the swelled

butts of trees of species such as sweetgum, túpelo,

and ash grown in swampy soil usually contain

very light wood with low strength properties;

higher in the trunks of the same trees the wood is

heavier and stronger.

The water in green wood often weighs more

than the ovendry weight of the wood, but in

thoroughly air-dried lumber the weight of water

is usually about 12 to 15 percent of the ovendry

weight of the wood, and in kiln-dried lumber it is

often as low as 5 percent.

The weight of some pieces of certain species,

such as southern yellow pine, western larch, and

Douglas-fir, is often materially increased by resin

1 U.S. Forest Products Laboratory, Wood handbook.

U.S. Dept. Agr., Agr. Handbk. 72, 528 pp., illus. 1955.

5
TABLE 1.—Properties of wood species native to the United States that might be used for crate construction a:)

Common and botanical name of species

(1)

Hardwoods:

Alder, red {Alnus rubra)

Ash:

Black (Fraxinus nigrd)

Green {F. pennsylvanica)

Oregon (F. latifolia)

White {F. americana)

Aspen:

Bigtooth (Poplus grandidentata)

Quaking (P. tremuloides)

Basswood, American {Tilia americana)

Beech, American (Fagus grandifolia)

Birch:

Paper {Betula papyrifera)

Sweet (B. lenta)

Yellow (B. alleghaniensis)

Chestnut, Anierican (Castanea dentata)

Cottonwood :

Black (Populus trichocarpa)

Eastern (P. deltoides)

Cucumbertree (Magnolia acuminata)

Elm:

American ( Ulmus americana)

Rock ( U. thomasii)

Shppery {U. rubra)

Hackberry (Celtis occidentalis)

Hickory:

Bitternut (Carya cordiformis)

Mockernut (C tomentosa)

Pecan (C illinoensis)

Pignut (C. glabra)

Shagbark (C. ovala)

Shellbark (C. laciniosa)

Water (C. aquatica)

Magnolia, southern (Magnolia grandiflora)

Maple:

Bigleaf (Acer macrophyllum)

Black (A. nigrum)

Red (A. rubrum)

Specific

gravity,

ovendry,

based on

volume

when

green

(2)

0. 37

. 45

. 53

. 50

. 54

. 35

.35

.32

. 56

.48

. 60

. 55

.40

.32

.37

. 44

. 46

.57

.48

. 49

.60

. 64

.60

. 66

. 64

.62

. 61

.46

. 44

. 52

.49

Weight per

cubic foot

Green

(3)

Lb.

46

52

49

46

48

43

43

42

54

50

57

57

55

46

49

49

54

53

56

50

63

64

61

64

64

62

68

59

47

54

50

At 15

percent

moisture

content

(4)

Lb.

28. 8

35. 3

40. 7

38. 4

42. 7

27.3

27. 0

26. 0

44. 3

38. 9

47. 2

43. 4

30. 5

24. 5

28.9

34. 3

36. 3

44. 2

37.8

37. 4

46.0

51. 4

46.5

53. 4

51. 2

49.0

44. 6

35. 5

34. 2

40.9

37.0

Shrinkage from

green to ovendry

condition based

on dimensions

when green

Radial

(5)

Percent

4. 4

5. 0

4. 6

4. 1

4. 8

3.3

3. 5

6. 6

5. 1

3.6

3.9

5. 2

4. 2

4.8

4.9

4. 8

7. 8

4.9

7. 2

7.0

7. 6

5. 4

3. 7

4. 8

4.0

Tangential

(6)

Percent

7. 3

7.8

7. 1

8. 1

7. 7

7. 9

6. 7

9. 3

11. 0

8. 6

8. 5

9. 2

6. 7

8.8

11.0

8.9

11.5

10. 5

12. 6

6. 6

7. 1

9.3

8. 2

Static bending

Modulus

of

rupture

(7)

P.s.i.

6,500

6,000

9, 500

7,600

9, 500

5.400

5, 100

5, 000

8,600

6,400

9,400

8, 300

5,600

4,800

5,300

7,400

7, 200

9,500

8, 000

6, 500

10, 300

11, 100

9,800

11, 700

11,000

10, 500

10, 700

6,800

7,400

7,900

7,700

Modulus

of elasticity

(8)

1,000

p.s.i.

1, 170

1,040

1,400

1, 130

1,440

1, 120

860

1,040

1,380

1, 170

1,650

1,500

930

1,070

1,010

1,560

1, 110

1, 190

1, 230

950

1, 400

1, 570

1,370

1, 650

1,570

1,340

1, 560

1, 110

1, 100

1,330

1,390

Work to

maximum

load

(9)

In.-lb.

per

cu. in.

8. 0

12. 1

11. 8

12. 2

15. 7

Impact

bending

(height

of drop)'

(10)

5.

6.

5.

11.

16.

15.

16.

7.

5. 0

7.3

10. 0

11.8

19. 8

15. 4

14. 5

20.0

26. 1

14. 6

31. 7

23. 7

29.9

18. 8

15.4

8.7

12. 8

11. 4

Maximum

crushing

strength

(parallel

to grain) 1

(11)

In.

22

33

35

39

36

18

22

16

43

49

48

48

24

20

21

30

38

54

47

48

66

88

53

89

74

104

56

54

23

48

32

P.s.i.

2,960

2, 300

4,200

3, 510

3,990

2, 500

2, 140

2 220

3! 550

,360

, 740

, 380

,470

2. 160

2, 280

3, 140

2,910

3,780

3, 320

2, 650

4,570

4, 480

3, 990

4,810

4,580

3,920

4,660

2,700

3, 240

3, 270

3, 280

Hardness

(side

grain) 1

(12)

Lb.

440

520

870

790

940

370 ^

300 en

250 i^

850 ^

560 9"

970 ^

780 §

420 3

250 o

340 ^

520 ^

O

620 ?ö

940 o

660 S

700 S

1,310

740

620

840

700
Silver (A. saccharinum)

Sugar {A, saccharum)

Oak:

Black {Quercus velutina)

Bur {Q. macrocarpa)

Chestnut (0. prinus)

Laurel {Q. laurifolia)

Northern red {0. rubra)

Pin (Q. palustris)

Post {Q. stellata)

Scarlet {Q. coccínea)

Southern red {Q. falcata)

Swamp chestnut {Q. michauxii)

Swamp white (0. bicolor)

Water ((?. nigra)

White (Q. alba)

Willow (0. phellos)

Sweetgum {Liquidambar styraciflua)

Sycamore, American {Platanus occidentalis)

Tupelo:

Black {Nyssa sylvatica)

Water (A^. aquaiica)

Yellow-poplar {Liriodendron iulipifera)

Softwoods:

Baldcypress {Taxodium distichum)

Cedar :

Alaska- (Chamaecyparis nootkatensis)

Atlantic white- (C. thyoides)

Eastern redcedar {Juniperus virginiana)

Incense- {Libocedrus decurrens)

Northern white- {Thuja occidentalis)

Port-Orford- {Chamaecyparis lawsoniana)

Western redcedar {Thuja plicata)

Douglas-fir :

Coast type {Pseudotsuga menziesii)

Intermediate tj^pe (P. menziesii)

Rocky Mountain type (P. menziesii var.

glauca).

Fir:

Balsam {Abies balsamea)

California red (^4. magnifica)

Grand {A. grandis)

Noble {A. procera)

Pacific silver {A. amabilis)

White {A. concolor)

Hemlock:

Eastern( Tsuga canadensis)

Western (T. heterophylla)

Larch, western {Larix occidentalis)

See footnote at end of table.

44 45 33.

9 3.0 7.

2 5,800 940 11.0 29

56 56 44.

5 4.9 9.

5 9, 400 1, 550 13.

3 40

56 62 44.

0 4.

5 9.

7 8,200 1, 180 12-2 40

58 62 45.

0 4.

4 8.

8 7,200 880 10.

7 44

5V 61 44.

7 5.

5 9.

7 8,000 1,370 9.4 35

56 65 45.

5 4.

0 9.

9 7,900 1,390 11.2 39

56 63 43.

8 4.0 8.2 8,300 1, 350 13.

2 44

58 63 45.

0 4.

3 9.

5 8,300 1,320 14.

0 48

60 63 47.

9 5.9 9.8 8, 100 1,090 11.

0 44 6Ü 62 47. 0 4. 6 9. 7 10, 400 1,480 15.0 54

52 62 41.

1 4.

5 8.7 6,900 1, 140 8.0 29

60 65 48.

5 5.

9 9.2 8, 500 1,350 12.

8 45

64 69 51.3 5,

5 10.

6 9,900 1, 590 14.

5 50

56 63 44.

6 4.

2 9.3 8,900 1,550 11.

1 39

60 62 46.8 5.3 9.0 8,300 1,250 11.

6 42

56 67 44.

6 5.

0 9.6 7,400 1,290 8.

8 35

46 62 36.4 5.4 10.

2 7, 100 1,200 10.

1 36

46 52 35.

7 5.

1 7.6 6,500 1,060 7.

5 26

46 45 36.

4 4.

4 7.

7 7,000 1,030 8.

C 30

46 56 35.

1 4.

2 7.

6 7, 300 1, 050 8.3 30

40 45 30.

3 4.

2 7.6 6,000 1,220 7.5 26

42 51 32.

6 3.8 6.2 6, 600 1, 180 6.6 25

42 36 31.

6 2.8 6.

0 6, 400 1, 140 9.2 27

31 26 23.

8 2.8 5.

2 4,700 750 5.9 18

44 37 33.

5 3.

1 4.

7 7, 000 650 15.

0 35

35 45 25.

5 3.

3 5.2 6, 200 840 6.4 17

29 28 2L8 2.

1 4.

7 4,200 640 5.

7 15

40 36 30.

1 4.

6 6.9 6, 200 1, 420 7.4 21

31 27 23.

4 2.4 5.

0 5, 100 920 5.

0 17

45 39 34.

3 4.

8 7.6 7, 600 1,570 7.6 26

41 38 31.

5 4.

2 7.

4 6, 800 1,350 6.

6 21

40 35 30.

5 3.

6 6.2 6,400 1, 180 6.8 20

34 45 26.9 2.

8 6.6 4,900 960 4.7 16

37 50 28.

3 4.

5 7.9 6, 000 1, 210 6.4 21

37 45 28.3 3.

2 7.

2 6, 100 1,300 5.6 22

35 30 27.

1 4.

5 8.3 5,800 1, 270 6.

0 19

36 38 28.

1 4.5 9.4 5,900 1,330 6.

6 21

35 47 26.

7 3.

2 7.

0 5, 700 1, 030 5.

1 22

38 50 29.0 3.

0 6.8 6,400 1,070 6.

7 21

38 41 29.

6 4.3 7.9 6, 100 1, 220 6.8 22

51 50 9.

4 4.

5 9.

1 8, 200 1,530 10.

3 29

3, 580

2,490 590

4, 020 970

3,470 1,060

3,290 1, 110

3,520 890

3, 170 1,000

3,440 1,000

3,680 1,070

3,480 1,130

4,090 1,200

3,030 860

3,540 1, 110

4,360 1, 160

3,740 1,010

3, 560 1,060

3,000 980

3,040 600

2,920 610

3,040 640

^

3, 370 710

OO

2,660 440

390

3, 050 440 L-y

2, 390 290

ö

3, 570 650 C/2

3, 150 390

Q

1,990 230

3, 130 400

2, 750 270

^

3, 860 500

^

3, 300 450

>

3, 000 400 tr"

2, 400 290

2, 850 360

3, 020 360

2, 740 290

2, 840 350

2,710 330

3,080 400

2,990 430

3,990 510
TABLE \.—Properties oj wood species native to the United States that might be usedfor crate construction—Continued

Common and botanical name of species

(1)

Softwoods—Continued

Pine:

Eastern white {Pinus strohus)

Jack {P. hanksiana)

Lodgepole (P. contorta)

Ponderosa (P. ponderosa)

Red (P. resinosa) _.

Southern yellow:

Loblolly (P. taeda)

Longleaf (P. palusiris)

Shortleaf (P. echinata)

Slash (P. elliottii)

Sugar (P. lamhertiana)

Western white (P. montícola)

Redwood, old-growth {Sequoia sempervirens)

Spruce:

Black (Picea mariana)

Engelmann (P. engehnannii)

Red (P. ruhens)

Sitka (P. sitchensis)

White (P. glauca)

Tamarack (Larix laricina)

Specific

gravity,

ovendry,

based on

volume

when

green

(2)

0.34

. 40

.38

.38

. 41

. 47

. 54

. 46

. 54

.35

.36

.38

.38

.32

.38

.37

.37

.49

Weight per

cubic foot

Green

(3)

Lb.

37

40

39

47

49

53

55

52

58

51

35

50

32

35

34

33

35

47

At 15

percent

moisture

content

^ Results from small, clear specimens in the green condition.

(4)

Lb.

25.4

30. 3

29. 2

28. 9

31. 4

36.3

41. 6

35. 7

41. 7

26. 0

28. 0

28. 6

28. 8

24. 1

28. 4

28. 1

29. 4

37.6

Shrinkage from

green to ovendry

condition based

on dimensions

when green

Radial

(5)

Percent

2. 1

3. 7

4. 5

3.8

3.8

4. 8

5. 1

4. 4

5. 4

2.9

4. 1

2. 6

4. 1

3.6

3.8

4. 2

3.8

3. 7

Tangential

(6)

Percent

6. 1

6. 6

6. 7

6. 2

7. 2

4. 4

6.8

7. 1

7.8

7. 5

7. 5

7. 4

Static bending

Modulus

of

rupture

(7)

P.s.i.

4,900

6,000

5, 500

5, 100

5,800

7,300

8,700

7,300

8,600

5, 100

5,200

7,500

5,400

4,500

5.800

5,700

5,600

7,200

Modulus

of elas

ticity

(8)

1,000

p.s.i.

990

1,070

1,080

970

1,280

1,410

1,600

1,390

1,590

940

1, 170

1, 180

1,060

960

1, 190

1,230

1,070

1,240

Work to

maximum

load

(9)

In.'lb.

per

cu. in,

5. 2

7. 2

5.6

5. 2

6. 1

8. 2

8.9

8. 2

9. 6

5. 4

5. 0

7. 4

7.4

5. 1

6. 9

6.3

6. 0

7.2

Impact

bending

(height

of drop)^

(10)

In.

17

26

20

21

26

30

35

30

35

17

19

21

24

16

18

24

22

Oft

Maximum

crushing

strength

(parallel

to grain) 1

(11)

P.s.i.

2, 440

2,950

2,610

2,400

2,730

3,490

4,300

3,430

4,210

2, 530

2,650

4,200

Hardness

(side

grain) ^

(12)

Lb.

290

400

330

320

340

450

590

440

580

310

310

410

2,570 370

2, 190 260

2,650 350

2,670 350

2,570 320

3,480 380

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d

d

S

Ü

Cd

O

o

to

o^

to

çî

¿o

ü

H

O

>

O

SJ

H

O

d

d
WOOD CRATE DESIGN MANUAL 9

Other Factors Affecting Wood Strength

Some important factors besides species that

affect the strength of lumber used for crates are

(1) moisture content, (2) duration of load, and

(3) size, number, and location of strength-reducing

characteristics, such as knots and cross grain.

Moisture content.—The wood of live trees contains tremendous quantities of water, which is

slowly lost after trees are cut, and particularly

after they are sawed into lumber. For most uses

of wood, including crates, almost all moisture must

be removed.

Moisture is held in wood within the cell cavities

and the cell walls. Wlien all the moisture has

evaporated from the cell cavities, but the cell

walls remain saturated, wood is said to have

reached the fiber-saturation point. For practical

purposes, the fiber-saturation point is considered

to be 30 percent moisture content for most species.

Moisture content is the weight of the water contained in the wood expressed as a percentage of

the weight of the ovendry wood.

As wood loses moisture below the fiber-saturation point, it begins to shrink. Wood dried to 15

percent moisture content has shrunk about half

as much as possible. If dried in an oven, a sample would continue to shrink as moisture is lost,

until reaching 0 percent moisture content.

Actually, wood wiU stop drying when it reaches

equilibrium with the temperature and humidity

surrounding it. This point, known as the equilibrium moisture content, varies widely with climatic

conditions and use of the wood.

As wood dries, the fibers begin to stiffen and

strengthen when the fiber-saturation point has

been reached. But toughness and shock resistance sometimes actually decrease. This is

because dried wood will not bend as far as green

wood before failure (although it will sustain a

greater load), and toughness is dependent upon

both strength and pliability.

The gain in strength of large members by drying

is somewhat offset by the accompanying splitting

and checking. A change from green condition to

12 percent moisture content, however, can result

in a 30 to 100 percent increase in strength in the

various species. The following tabulation represents the average change in wood and strength

properties with a 1 percent change in moisture

content (between approximately 30 and 12 percent).

Changes

(percent)

Static bending:

Modulus of rupture 4. 0

Modulus of elasticity 2. 0

Work to maximum load .5

Impact bending, height of drop causing complete

failure . 5

Maximum crushing strength (parallel to grain) 6. 0

Side hardness 2. 5

Duration of load.—Wood is able to support

large overloads for short periods and small overloads for longer periods. This property is important if short-time load is contemplated, such

as a one-trip crate shipped directly to its destination with no storage period. However, it is better

to disregard it in designing crates for longtime

storage. A wood member can support continuously for 1 year only about two-thirds of the load

required to cause failure in a standard strength

test of only a few minutes' duration.

Wood under a continuous load, such as might

be imposed on a crate in storage with other boxes

or crates placed on top, tends to deform. The set

or sag of the joists, an illustration of this, is greatest

when moisture content of the material is high.

Knots.—Knots are cross sections of branches

that are \asible on the surface of a piece of wood.

They interrupt the direction of grain and cause

localized cross grain with steep slopes. While

some types of knots affect the resistance to stresses,

no distinction is made between live knots, dead

knots, and knotholes in determining the strength

value of any piece of lumber. In building crates

both size and location of knots must be considered.

The effect a knot has on the strength of a piece

of lumber depends on the proportion of the cross

section occupied by the knot. Limits of knot

sizes should therefore be based on the width of the

face in which the knot appears.

Ejiots reduce tensile strength more than compressive or shear strength, and their location along

the length of the piece is considered only in bending. Knots located near midspan and at the top

or bottom edges have the most effect on the

strength of a piece subjected to bending. A sound

knot at the top part of a joist near midspan is in

compression and usually has only a moderate

inñuence on the strength of the piece in bending.

Slope oj grain.-—Slope of grain refers to the direction of the wood fibers in relation to the longitudinal axis of a piece of lumber. When these

fibers are not parallel with the longitudinal axis,

the wood is said to be cross grained. The slope,

measured by the angle between the general direction of the grain and the axis, is expressed as a

ratio, as 1 in 12 (1-inch slope in a 12-inch distance).

Slight local de\âations of grain direction are usually

disregarded. When cross grain is quite steep,

there is a marked reduction in strength. A slope

of grain of 1 in 8 in a member subjected to bending under impact loads will result in its having 53

percent of the strength of a piece without grain

deviation. This requires a reduction in the

assigned working stresses to offset the loss in

strength. Besides having less strength, pieces

with cross grain tend to twist with changes in

moisture content.

Slope of grain, therefore, must be limited for

such crate parts as joists, load-bearing floorboards,

struts, upper and lower frame members, diagonals.
10 AGRICULTURE HANDBOOK 2 5 2, U.S. DEPT. OF AGRICULTURE

and skids of sheathed crates. Fewer restrictions

on slope of grain exist for items such as lumber

sheathing, rubbing strips, and nonstructural blocking and bracing than for structural members.

Decay,—Decay, a disintegration of wood, results from the action of wood-destroying fungi.

It seriously affects the strength properties of wood

and its resistance to nail withdrawal.

Blue stain.—Also called sap stain, this bluish

discoloration of the sapwood is caused by a fungus.

It does not reduce the strength of the wood.

However, the conditions that favor development of this fungus are also ideal for the growth

of wood-destroying fungi, so bad staining may

indicate existence of decay. When blue stain

is present in sheathing boards or frame members,

it may obscure markings on the crate.

Insect attack.—Certain woods are subject to

insect attack as green lumber, some as dry lumber, and some as partly seasoned lumber. The

sapwood of some seasoned hardwoods is subject to attack by the powder-post beetle. Small

wormholes have only a very slight effect on the

strength and, if the wood is otherwise sound,

it is quite satisfactory for crates.

Wane.—Wane is either bark or lack of wood

on the edge or corner of a piece of lumber. Acceptability of pieces with wane is usually restricted for structural members because of the

reduced cross sectional area. Wane is less serious

in lumber sheathing than in such crate parts as

frame members and skids.

Shakes.—A shake is a separation along the

grain, largely between the growth rings, which

occurs while the wood is seasoning. Shakes in

rnembers subjected to bending reduce the resistance to shear and therefore should be closely

limited in structural members. Restrictions of

shakes in boards are usually based on the length

of the split or opening.

Checks and splits.—Checks and splits, lengthwise openings from separations during seasoning,

may reduce wood's resistance to shear. They

are judged on the basis of the area of actual

opening. An end split is considered the same as

an end check that extends through the full thickness of the piece.

Warping.—WsLvping is any variation of a piece

of material from a true or plane surface and includes bow, crook, cup, and twist. Generally

warping does not affect the strength of crate

parts, but it makes fabrication more difficult

and reduces the utihty of the container.

Working Stresses

In calculating the proper size of crate members workmg stresses must be assigned to the

wood to be used. The magnitudes of working

stresses vary generally by species, the denser

woods havmg the higher values. However a

number of other factors determine the final

working stress. These include moisture content,

variability within the species, impact loading

consideration, and strength-reducing characteristics.

The following is a system of computing basic

stresses for crate lumber, and then applying reductions to obtain working stresses.

1. The strength of green lumber of a species,

based on average laboratory values of small clear

specimens, is selected as a starting point. This

assumes that the lumber will be stressed at some

time when it is wet.

2. The green value is then reduced by a variability factor, because the strength of any species

of wood is variable. The factor used for structural

lumber is usually three-fourths. It means that

only about 5 out of every 100 pieces will be weaker

than three-fourths of the green value.

3. A factor for impact loading is then applied.

In handhng and shipping, stresses are applied by

lifting, handhng, and dropping accidentally. These

impact stresses are much greater than the static or

slowly apphed loads, such as top loads in storage.

The usual factor for impact loads is about onethird.

Basic stresses, obtained by applying these two

factors, correspond to clear lumber grades and

provide a measure of the inherent strength of

clear wood.

4. Finally, allowances are made for the maximum effect of such characteristics as knots and

cross grain. Table 2 shows reduction factors.

The larger factor, whether for knots or cross

grain, is the one used. When the basic stresses

are reduced by these factors, they become the

working stresses.

An example of the way a working stress for a

crate is ordinarily computed from laboratory test

values for white fir is given below. Wliite fir was

picked because it is one of the weakest woods used

in container construction.

Green modulus of rupture=5,700 pounds per

square inch

(table 1)

Variability factor = %

Impact factor = %

Basic stress=5,700X%XK= 1,425 pounds per

square inch

For maximum allowable knot sizes equal to

one-fourth of the width and for cross grain up to

1 in 15, the reduction factor is 25 percent.

Working stress= 1,425—(0.25X1,425) =1,069

pounds per square inch

Working stresses for other species may be deterniined in a similar manner. The crate designer

dealing with several species in the same wood

group should select an average working stress

suitable for all.
WOOD CRATE DESIGN MANUAL 11

For structural uses, basic stresses are given in

the Wood Handbook ^ for various species. Also

included is a discussion of strength ratios which,

when applied to basic stresses, yield w^orking

stresses. Thus allowable w^orking stresses can be

calculated for various grades of lumber, such as

^'structura?' and ''nonstructural."

TABLE 2.—Reduction factors used to compute

working stresses from basic stresses

Strength in—

Strength-reducing

characteristic

Tension Compression

Bending

Flat On edge

Knots:

One-fourth of

the width

One-third of the

width

One-half of the

width

Cross grain:

1 in 20

1 in 15

1 in 10

Percent

25

33

50

0

24

39

47

60

Percent

13

17

25

0

0

26

34

44

Percent

25

33

50

0

24

39

47

60

Percent

143

153

174

0

24

39

1 in 8

1 in 6

47

60

1 Knots assumed to be in the worst position, at the center of the length and at the edge of the wide face.

The lumber grades are based on the size, location, and number of strength-reducing characteristics in species used for miscellaneous construction. The lumber used for frame members and

sheathing of crates is usually of a lower grade than

that listed in the tables and consequently would

have somewhat lower values for the allowable

working stresses.

To calculate basic stresses for structural lumber, impact loading is generally ignored, but

longtime loading and a safety factor are considered. A piece of wood will carry less load for a

long time than it will for the short period of the

laboratory test. The reduction factor for longtime loading is between nine-sixteenths and threefourths. After it is applied, the piece is considered capable of supporting its load for a long time.

A safety factor of three-fifths or two-thirds is

then appHed to take care of other conditions of

loading that are indeterminate but tend to reduce

the strength.

The combined longtime loading and safety

factors are about equal to the impact loading

factor used for crate lumber. Therefore, for

structural lumber and crate lumber, basic stresses

are approximately equal.

^ See footnote 1, p. 5.

Lumber Sizes

Most of the lumber used for crates is nominally

1 or 2 inches thick. However, such members as

skids, headers, load-bearing floorboards, and fastening members often are thicker. All nominal

dimensions are normal rough-sawn widths and

thicknesses, and any dressing or surfacing will

reduce them. Face dressing may be Si S or S2S

(surfaced 1 or 2 sides). Edge dressing may be

SlE or S2E (surfaced 1 or 2 edges). When both

faces and both edges of a piece of lumber are

surfaced, the cross section should have minimum

thickness and width. These minimum allowable

dimensions, for any combination of surfacing and

edging, should follow those hsted in table 3.

Unless designated otherwise, the lumber dimensions in this handbook are nominal.

When sizes other than those listed in table 3

are used, undersize in thickness or width due to

mismanufacture may be permitted in not more

than 10 percent of the pieces. However, no part

should be thinner than seven-eighths of the

required thickness, or narrower than one-fourth

inch less than the required width.

Rough lumber is used for the base of most

crates and for the framing of sheathed crates.

At least one surface of all other members should

be dressed and placed on the outside of the crate

to receive marking.

TABLE 3.—Nominal and minimum allowable dimensions oj softwood lumber ^ for crates

Thickness (smaller

dimension)

Width (larger

dimension)

Nominal Minimum Nominal Minimum

Inches

1

2

Inches

1%

2%

H less

Inches

2

3

4

5

6 and wider

Inches

2%

3 3%

4

5 and thicker. _ Yi less

1 Hardwood lumber is bought and sold on a basis of

actual rather than nominal dimensions. The minimum

allowable dimensions listed here are applicable to hardw^oods.

2 In American Lumber Standards, the actual thickness

for a nominal 1-inch board is ^^^2 inch. The ^i-inch

thickness Hsted is not intended to represent lumber standard, but rather is one of the thicknesses of softw^ood lumber

used in crate design.

Plywood

Plywood is a sheet material made of three or

more layers of thin wood veneer glued together.

The grain of each ply is placed at an angle, usually

90"", with the grain of the adjoining ply. The
12 AGRICULTURE HANDBOOK 2 5 2, U.S. DEPT. OF AGRICULTURE

outside plies are called faces (or face and back) and

the center ply or plies are called the core. Plywood of three, five, seven, or more plies, depending;

on the type and thickness, is used as sheathing for

crates of all sizes.

The strength properties of plywood depend

upon the species of wood and the number and

thicknesses of the plies. As the number of plies is

increased, the strengths parallel and perpendicular

to the face plies become more nearly equal, assuming the plies are all about the same thickness.

The resistance to splitting also increases rapidly

with the number oi plies (table 4). When plywood is composed of a very large number of plies

of the same thickness or if the middle layer of

three-ply stock is about seven-tenths the total

thickness, the bending strength is about the same

either parallel or perpendicular to the grain of the

face plies.

Grades and types.—The plywood used for sheathing material in crates complies with sheathing material specifications. The two classes of plywood are

hardwood plywood and softwood plywood. While

much softwood plywood is made of Douglas-fir,

hardwood plywood is made of many species.

Grade of plywood is determined by the quality of

the outside plies. Type of plywood is determined

by the moisture resistance of the glue joints.

TABLE 4.—Effect of nvmber of plies on strength properties oj plywood oj the same total thickness

Number of plies

B ending strength Strength in tension

Parallel ^

Perpendicular 2

Ratio of

perpendicular

to parallel

Parallel i

Perpendicular 2

Ratio of

perpendicular

to parallel

Resistance

to splitting

3

5

7

Percent

ino

74

72

51

Percent

100

167

193

182

Percent

20

45

54

72

Percent

100

96

90

77

Percent

100

113

119

109

Percent

58

68

78

83

Percent

100

185

235

9-- 340

1 Stress applied parallel to grain of face plies.

2 Stress applied perpendicular to grain of face plies.

Exterior and Interior are the two types of

softwood plywood. Exterior is expected to be

suitable for permanent exterior use. Interior is

expected to retain its form and most of its strength

when only occasionally subjected to wetting and

drying. Several grades are established within

each type by the quahty of the veneer on the two

faces of a panel. In Douglas-fir plywood the

veneer is designated as A, B,"C, or D, in descending order of quahty.

Hardwood plywoods are of four types—

Technical, Type I, Type II, and Type III.^ Principal difference between types is in the resistance

of the glue bond to severe service conditions.

Glue bonds in both Technical and Type I are high

in durability, corresponding to Exterior-type

Douglas-fir plywood. These two tvpes differ

only in the permissible thickness and arrangement

of phes. Resistance of glue bonds of Type II

hardwood plywood resembles that of Interiortype Douglas-fir plywood. Type III hardwood

plywood has glue bonds with good dry strength

but no moisture resistance. Grade of'hardwood

plywood is determined by the quahty of the

veneer on the face and back of a panel. The

veneer is graded 1, 2, 3, and 4, in descending

order oí quality.

For use in crates, these are the o-eneral

groupmgs:

Exterior-type softwood plywood and Technical

and Type I hardwood plywood are weatherproof

and are ordinarily employed for reusable crates

that will meet severe exposure conditions. These

types may have surfaces treated with a water

repellent or untreated.

Interior-type softwood pljnvood and Type II

hardwood pl^^wood are moisture resistant and are

ordinarily used for crates to be shipped overseas

or exposed to moderate weather conditions in

shipping or storage. These also are treated or

untreated.

Type III hardwood plywood is used for ordinary

shipping crates where little outdoor storage is

contemplated. It comes in untreated or treated

forms.

Special qualities oj plywood use.—Pl3rwood has

the following advantages as a sheathing material

for crates:

1. Its use eliminates the need for diagonals,

which are ordinarily required for lumber-sheathed

crates. Plj^wood sheathing resists racking and is

very rigid in panel form when perimeter nailing is

used.

2. Since plyivood is resistant to splits it is possible to nail close to the edges of the panel.

3. The shrinkage of plywood is so minor that it

need not be considered in crate design.

4. Plywood dimensions are actual, rather than
WOOD CRATE DESIGN MANUAL 13

nominal, so it is easy to calculate the amount

needed.

5. A plywood-sheathed crate does not require

a liner for waterproofing.

6. As the number of plies increase plywood approaches balanced construction, with moderate

bending strength in two directions.

7. The use of plywood reduces the cubic displacement required for lumber sheathing in most

crates because the plywood is usually not as thick

as lumber. Weight is also reduced because plywood is thinner and diagonals are not required.

With these advantages, there are some special

factors to be considered in using pl^^wood: (1) In

the thicknesses required for crates it usually costs

more than similar lumber sheathing. This must

be weighed against a possible saving in labor with

plywood. (2) Waste occurs more often. Vertical members can be spaced in modules to fit the

width of the sheet, but there is end waste when the

crate height does not correspond to the sheet

length. (3) A plywood-sheathed crate usually

requires struts more closely spaced than struts in

a similar lumber-sheathed crate.

Paper-Overlaid Veneer

Paper-overlaid veneer is a sheet nuiterial made

of a thin veneer core with paper facing on each

side. Among its uses is sheathing for lightweight

crates where heavier sheatliing to resist stacking

loads is not needed. Various core veneers are

used. One three-ply material, for example, has

a hardwood veneer core faced on eacli side with

kraft paper; core thickness may vary from onesixteenth to one-sixth inch. Another material has

a Douglas-fir veneer core and kraft paper facings;

core thickness is usually one-eighth to tlu^ee-sixteenths inch. Some of the materials have greater

bending strength in one direction because the

veneer core is much tliicker than the paper facings.

Other materials have more balanced strength because the paper facings are thick enough to increase

the crosswise bending strength.

Paper-overlaid veneers that are used in slieathing crates are generally much thinner than plywoods and lack their resistance to nailhead pullthrough. Therefore, it is necessary to use nails

with larger heads and space them somewhat closer

to insiu-e good fabrication strength. Because of

the deñection of paper-overlaid veneer, it is necessary to use closer spacing for struts and other

framing members than is ordinarity used for plywood-sheathed crates. However, for sheathing

lightweight crates using nominal 1-inch-thick

framing material, paper-overlaid veneer can be

specified successfully by the crate designer.

FASTENINGS

The strength and rigidity of crates are highly

dependent on the fastenings. Nails, lag screws.

bolts, screws, and metal connectors are the most

important fastenings in crate construction. Recent

developments by the manufacturers of staples and

driving equipment indicate that staples may be

satisfactory substitutes for nails. Advances in

adhesive research may also make glued fabrication

of crates practicable.

Crate fastenings have two general purposes:

fabricating the parts to form panels, and assembling the panels. Nails are used almost invariably

for fabrication, while nails and other types of

fastenings may be used for assembly.

Nails

Nails are the fasteners most commonly used in

crate construction. Many standard types and

sizes are used in addition to special-purpose nails.

Fabrication, such as nailing the sheathing to the

frame members, usually involves driving the nails

tln*ough two or more pieces and clinching them.

Chnching the nails greatly increases their

withdrawal resistance. In assembly, however,

clinching the nails is usually impractical, so their

\vithdrawal resistance depends on the type and

size of the nail shank and the depth of penetration.

Nail types.—The nails most commonly used in

the construction of crates are common, sinker,

and cooler nails.^ Shank treatment is not necessary for nails clinched in fabrication. Surface

coating or roughening or shank deformation

increases the withdrawal resistance of nails used

in assembly. Often used are cement-coated

nails of the sinker, cooler, or box type. Figure 4

shows the common, bright box, cement-coated

coolers and sinkers, the clout, and deformedshank nails.

Common and bright box nails are those most

often used in fabrication nailing where clinching

is required. They are the same length in each

size, but the box nail is slightly smaller in diameter.

Clout nails are commonly used to fasten plywood

or other sheet materials to the thinner frame

members of crates. These nails are comparatively

short, with long duckbill points that clinch easily

and larger heads than other container nails of

comparable length.

Nail sizes.—The size of most nails is based on

their length; the diameter or gage varies by the

length and the nail type. Nail size is usually

expressed by the penny system, abbreviated as d.

For example, a sixpenny nail is expressed as 6d

and an eightpenny as Sd. The penny system

originated in England and is said to have been

based on the weight of a thousand nails. For

example, 1,000 tenpenny nails weighed 10 pounds,

and 1,000 eightpenny nails weighed 8 pounds.

3 Anderson, L. 0. Nailing better wood boxes and

crates. U.S. Dept. Agr., Agr. Handbk. 160, 40 pp.,

illus. 1959.
14 AGRICULTURE HANDBOOK 2 5 2, U.S. DEPT. OF AGRICULTURE

A

GAGE NUMBER 2

H

Figure 4.—Nail types: A, Common; B, bright box; C, cooler

(cement coated); D, sinker (cement coated); E, clout; F,

spirally grooved; G, annular grooved; H, barbed.

Present lengths, gages, and number per pound of

several standard types of nails are shown in

table 5.

Calculating nail-holding capacity.—During

handling and shipping of crates, the nails are

subjected to direct withdrawal and lateral forces.

Direct withdrawal resistance is the resistance of

a nail to forces parallel to its axis that tend to

pull it from a piece of wood. Lateral resistance

is the resistance of a nail to forces applied at

right angles to its length. These resistances can

be calculated.

TABLE 5.—Length, gage, and number per pound for

standard sizes and kinds of nails commonly

used in crates

LENGTH

Size of

Bright Cement-coated

nail '

Common Box Sinkers Coolers Box

2d

3d

4d

5d

6d

7d^^,.

8d

9d

lOd

12d

Inches

1

1/

1/

1/4

2

2/4

2/

3

3/4

3/

4

4/2

5

5/

6

Inches

1

1/

1/

1/4

2

2/4

2/

2/4

3

3/4

3/

4

Inches

\V¡

1%

1/8

1/8

2/8

2/8

2/9

2/8

3/8

3/4

VA

4/4

4/4

5/

5/4

Inches

1

1/8

1%

1%

1/8

2/8

2/8

2%

Inches

i/s'

1/8

1/3

1/8

2/8

2/8

2/8

2/8

16d

20d

30d

40d

50d

60d

Bright Cement-coated

Size of

nail * Common Box Sinkers Coolers Box

Inches Inches Inches Inches Inches

2d 15 15H 16

3d 14 14/2 15/2 15/2 16

4d 12/2 14 14 14 15/2

5d 12/2 14 13^2 13/2 15

6d iiM 12/2 13 13 13/2

7d 11/2 12/2 12H 12/2 I3K2

8d lOK 11/2 11/2 11/2 12/2

9d 10/4 IIK2 11/2 12/2

lOd 9 lOH 11 11 IIH

12d 9

8

6

5

4

3

2

10/2

10

9

10

9

7

6

5

4

3

16d

20d

30d

40d

50d

60d

APPROXIMATE NAILS PER POUND

NumhpT Number Number Number Number

2d 830 1,010 1,094

3d 528 635 850 848 988

4d 316 473 495 488 710

5d 271 406 364 364 522

6d 168 236 275 275 310

7d 150 210 212 212 283

8d 106 145 142 142 191

9d 96 132 130 172

lOd 69 94 104 104 118

12d 63

49

31

24

18

14

11

88

71

52

77

61

37

29

21

16

13

16d

20d --

30d

40d

50d

60d

* Bolts are often preferred where nails larger than

twentypenny would be required.

2 Conformed to the American Steel and Wire Company

steel wire gage.

The resistance of a nail to movement is affected

by the density of the wood, the moisture content

of the wood and any changes in it, diameter of

the nail, depth of penetration into the wood,

surface condition of the nail shank, type of nailhead and point, direction of driving, and clinching.

Most of these factors have an influence on the

direct-withdrawal resistance of the nail; several

affect the lateral resistance and the splitting of

the wood.
WOOD CRATE DESIGN MANUAL 15

Density.—Specific gravity has been found to

be the best single standard upon which to base

the strength properties of wood. A general relationship exists between it and nail withdrawal

resistance. In woods of high density, the correspondingly liigii proportion of wood substance

offers greater resistance to (hstortion and, consequently, to nail withdrawal.

Moisture content.—When nails are driven into

pieces of wood of different moisture contents and

pulled immediately, some variations are evident

in the withdrawal resistance values. More important tîian the effect of moisture content, however, is the effect of change in moisture content.

A nail driven into green wood and pulled immediately has almost four times the withdrawal resistance it would have if it were pulled a year later,

after the w^ood had dried. Whenever any moisture

change occurs in wood, nails lose a large part of

their original resistance to Avithdrawal.

Diameter oj nail.—Nail diameter has much

effect on both lateral resistance and resistance to

direct withdrawal. The greater the diameter,

the greater is the resistance, but also the greater

is the hkehhood that the wood will split. This

is especially true of dense species when the moisture content is low.

De'pth oj pénétration.—The depth to which a

nail penetrates is directly related to its withdrawal

resistance because the deeper the penetration, the

greater the contact with the wood fibers. Withdrawal resistance is calculated on the basis of the

depth of penetration in inches. In lateral resistance a minimum penetration is required, and no

premium is allowed for greater penetration. Since

the nail is often subjected to both lateral and

withdrawal stress, good penetration has its

advantages.

Surface condition oj the nail.—To increase the

withdrawal resistance of the nail, the shank is

sometimes modified by coating, roughening, or

deforming it.

Surface coatings are usually of ''cement'' or

zinc. The cement-coated nail in particular has

a greater resistance to immediate withdrawal than

the common nail, but may lose much of this

advantage in a few months. Furthermore, different techniques for applying the coating and variations in the ingredients cause large differences in

the withdrawal resistance. In low-density woods

the cement coating, if properly apphed, adds

materially to withdrawal resistance. In denser

woods much of the coating may be removed as

the nail is driven.

Nail surfaces may be roughened by either

chemical etching or sandblasting. In both types

the roughened portions will engage the wood

fibers and provide some resistance to withdrawal.

Deformed-shank nails are designed to retain a

great percentage of their withdrawal resistance

even after the wood has undergone many changes

692-318 0—64 2

in moisture content. Tlie two most common

varieties are spirally grooved and annular grooved.

In general, annular grooved nails sustain larger

static-withdrawal loads than other nail forms,

and spirally grooved nails sustain greater impactwithdrawal loads.

Type oj nailhead and point.—Nailheads prevent

nailed pieces from pulling loose when a force is

applied. Nailheads vary in size and shape (fig. 5),

but most nails used in crates have a round, flat

head. The countersunk nailhead is strong enough

to withstand tlie force required to withdraw the

nail from most species of wood. Nails with thin,

flat heads should not be used in dense woods,

because the nailhead may be broken off or damaged

when the nail is driven, or when stresses are

applied. When nailheads are damaged, the

strength of the joint is greatly reduced.

r I Ü 1 I

H

Figure 5.—Various types of noil points and heads: A, Diamond;

B, needle; C, duckbill/ D, chisel/ E, blunted/ F, flat/ G,

countersunk/ H, broad flat.

Shape of the nail point has some influence on

withdrawal resistance. Nails with long, sharp,

conical points will usually have higher withdrawal

resistance than nails with the commonly used

diamond points (fig. 5). However, the sharppointed naiPs tendency to spht the denser species

of wood lowers its withdrawal resistance. Nails

with blunt or flat, untapered points do not spUt

wood so easily. They tear the wood fibers much

more, however, and therefore have lower withdrawal resistance than common wire nails.

Direction oj c/rmnr/.—Resistance of nails to

withdrawal is greatest when they are driven perpendicular to the grain of the wood. When they

are driven parallel to the wood fibers, as into the
16 AGRICULTURE HANDBOOK 2 5 2, U.S. DEPT. OF AGRICULTURE

ends of a piece, their holding!: power may drop to

as low as 50 percent of the side-o:rain values.

Slant driving has some advantages over straight

driving when nails are driven into the end grain

of wood.

Clinchimj.—Clinching is one of the best methods

of increasing the effectiveness of nails. It is used

almost entirely in the fabrication of crate panels,

except when frame members or other crate parts

are greater than 2 inches thick. Clinched nails

have 50 to 150 percent greater withdrawal resistance than unclinched nails when driven into dry

pine or Douglas-fir and pulled immediately.

Clinched nails in green wood that dries after the

nails are driven have 250 to 450 percent greater

holding capacity than unclinched nails of the same

diameter. Naüs that are clinched across the grain

are about 20 percent more effective than those

clinched with the grain.

Predrilling.—Predrilling the wood before the

nails are driven may be necessary to prevent

splitting in very dense woods or with nails of

large diameter. Prebored holes should be about

the same diameter as the nail shank. Splitting,

of course, reduces the effectiveness of any nail

used for fabrication or assembly and should be

prevented.

Direct-withdraival resistance.—The relative resistance to direct withdrawal of nails with circular,

uncoated, plain shanks depends on the specific

gravity of the wood, the nail diameter, and the

depth of penetration. The following formula may

be used to determine the allowable direct-withdrawal load for nails of any size under loading

conditions that are typical in crates :

P= 1,380 i?^/2ö

where P is the allowable load in pounds per lineal

inch of penetration into the member receiving the

point (side grain of seasoned wood); Q is the

specific gravity of the species, based on the weight

and volume when ovendry; and D is the diameter

of the nail in inches.

Table 6 fists the specific gravity, 0, and the

G^''^ value for a number of woods that may be

used in the construction of crates.

For convenience in determining withdrawal values of nails by the formula, table 7 lists nail

diameters and other data for the bright common

nail. When nails of other tj^es (such as sinkers)

are used, the gage, length, and other values will

change from those listed in the table.

The type of nail most often used in assembly of

crates is the cement-coated sinker nail. It is

available in a wide variety of sizes and has a strong

countersunk head. Table 8 lists the average

allowable load in direct withdrawal for plam

smker nails (or nails of equal diameter and penetration) m crate construction. These values are

considered satisfactory for loading and storage

conditions to which crates are normally subjected.

Under extreme conditions of shipping, storage, or

handling, allowable loads may be reduced. The

values given in table 8 do not include allowances

for any shank coating, roughening, or deformation. The additional resistance that a modified

shank provides may be considered a safety factor.

TABLE 6.—Values for specific gravity (G) of ovendry wood used in calculating direct-withdrawal

loads for nails and lag screws

G GV^ G3/2 G GV=^ G3/2

0. 29 0. 05 a 16 0. 50 a 18 0.35

. 31 .05 . 17 . 51 . 19 .36

. 32 .06 . 18 .52 . 19 .37

. 34 .07 . 20 .53 .20 .39

.35 . 07 . 21 . 54 . 21 .40

. 36 .08 . 22 . 55 .22 .41

.37 .08 . 22 . 56 . 23 .42

.38 .09 . 23 . 57 .25 .43

.40 . 10 .25 .58 . 26 . 44

. 41 . 11 .26 .60 .28 .46

. 42 . 11 .27 . 61 .29 .48

. 44 . 13 .29 .62 .30 .49

. 45 . 14 .30 .64 .33 .51

.46 . 14 . 31 . 66 .35 .54

. 47 . 15 .32 .67 .37 .55

. 48 . 16 . 33 .71 . 42 .60

. 49 . 17 . 34 .74 . 47 .64

TABLE 7.—Sizes of bright common wire nails

Diameter

Size Gage Length

D D3/2

Penny Inches Inch Inch

4 12/2 1/2 0.098 0. 0307

6 11/2 2 . 113 .0380

7 iiH 2}i . 113 .0380

8 10K4 2V2 . 131 . 0474

9 1OK4 2% . 131 .0474

10 9 3 . 148 .0570

12 9 3>i . 148 .0570

16 8 3/2 . 162 .0652

Lateral resistance.—In determining lateral resistance of a nail, the specific gravity or density of the

wood, as well as the nail diameter, must be considered. The formulas used to determine the

lateral resistance are based on the penetration of

an uncoated, circular shank nail into the main

member two-thirds of its length in low-density

woods and one-half of its length in high-density

woods. For their maximum holding capacity,

nails should therefore be long enough to penetrate

these distances.

The following formulas can be used for determining the allowable lateral resistance of nails

driven into the side grain of various kinds of wood.

The values are based on stresses normally placed

on crates.
WOOD CRATE DESIGN MAJSTCJAL 17

TABLE 8,—Average allowable loads ^ Jor nails in direct withdraioal ^ {nails equal in diameter and length to

sinker nails)

Wood species

Basswood, cottonwood, true firs, pines (except

southern yellow), spruce, yellow-poplar, and other

species of similar density

Western hemlock, red pine, redwood, other species of

similar density

Soft elm, sweetgum, black ash, soft maple, other

species of similar density

Douglas-fir, western larch, southern yellow pine,

other species of similar density

White ash, beech, birch, hard maple, oaks, rock elm,

other species of similar density

Allowable load

Sixpenny

Lb.

18

25

34

38

59

Eightpenny

Lb.

27

37

51

56

Tenpenny

Lb.

35

48

66

73

114

Twelvepenny

Lb.

42

58

81

89

140

Sixteenpenny

Lb.

49

66

93

102

159

Twentypenny

Lb.

58

79

111

121

190

1 Based on normal conditions for crates.

2 When driven in side grain of seasoned lumber to a depth equal to two-thirds of its length.

Species

Basswood, cottonwood, true firs,

pines (except southern 3^eIlow),

spruces, yellow-poplar, other

species of similar density

Western hemlock, red pine, redwood, other species of similar

density

Soft elm, sw^eetgum, black ash,

soft maple, other species of

similar density

Douglas-fir, western larch, southern yellow pine, other species of

similar density

White ash, beech, birch, hard

maple, oaks, rock elm, other

species of similar density

Formula

p=l,350Z)3/2

P==i 5000^/2

P=l,650ü 3/2

P=2,040Ö3/2

In these formulas, P is the allowable load per nail

in pounds and D is the diameter of nails in inches.

The values for D^^"^ for the various sizes of nails

are given in table 7.

For convenience of the crate builder, table 9

covers the average allowable loads for sinker nails

in lateral resistance. This table is satisfactory for

sinker nails or nails of equal diameters in crates

under normal storage and handling conditions.

Nailing rules.—The following good nailing

methods and general rules are used in the fabrication and assembly of crates. Many are based on

the engineering analysis of holding capacity of

nails, while others are based on practices found

to be satisfactory.

1. Unless nails are clinched, use cement-coated,

etched, or deformed-shank nails to gain increased

TABLE 9.—Average allowable loads \for nails in lateral resistance ^ (nails with diameters equal to sinker nails)

Allowable load

Wood species

Sixpenny

Eightpenny

Tenpenny

TwelvepennySixteenpenny

Twentypenny

Basswood, cottonwood, true firs, pines (except southern yellow), spruce, yellow-poplar, other species of

similar density __ _. .___

Lb.

30

37

42

46

56

Lb.

41

51

57

63

78

Lb.

45

57

63

69

85

Lb.

54

67

75

82

101

Lb.

62

77

86

94

117

Lb.

81

Western hemlock, red pine, redwood, other species of

similar density

Soft elm, sweetgum, black ash, soft maple, other

species of similar density _ _ _

101

112

Douglas-fir, western larch, southern yellow pine, other

species of similar density _ 123

White ash, beech, birch, hard maple, oaks, rock elm,

other species of similar density - _ 152

* Based on normal storage and handling conditions.

2 When driven in side grain of seasoned lumber, minimum distance of penetration equal to two-thirds of its length in

the softer woods or one-half in the denser woods.
18 AGRICULTURE HANDBOOK 25 2, U.S. DEPT. OF AGRICULTURE

withdrawal resistance. Nails used for assembling

crates should have a diameter at least equal to

that of a sinker nail (table 5) and a strong head of

moderate size to prevent the head from sliearing

off or pulling through the wood.

2. In the fabrication of panels for sheathed

crates, it is desirable to hold the members^ in

alinement while the sheathing is applied. This

may be done by jigs or by fastening frame members to each other with corrugated fasteners or

staples before the sheathing is applied.

3. Whenever possible, nails should be driven

through the thinner piece into the thicker. This

is especially important when plywood is fastened

to nominal 1- or 2-inch members.

4. ^^Tien nailing two pieces of lumber together

flatwise, as in fabrication, the nails should l)e

clinched if the combined thickness is 3 inches or

less. A }:i-inch minimum clinch should be used

for nails up to sevenpenny, a ^s-inch clinch for

for eightpenny through twelvepenny nails, and a

K-inch clinch for larger nails. Plywood % inch

or less in thickness may be nailed to nominal

2-inch members without clinching if the nails

penetrate IK inches into the members.

5. Nails are not clinched when the combined

thickness of two pieces of lumber nailed together

flatwise is more than 3 inches, or when the flat

face of one member is nailed to the edge of another.

Tenpenny and smaller nails should penetrate into

the piece for a distance equal to about 2 to 2}^

times the thickness of the piece holding the nailhead. Twelvepenny and larger nails should penetrate at least 1^ inches into the piece that holds

the point.

6. If diamond-point nails split the wood enough

to weaken it, the points should be blunted slightly.

If blunting does not prevent the splitting, nails

of the next smaller penny size should be used and

spaced a little closer together. Drilling lead holes

also will reduce splitting. Except for very large

members, predrilling is recommended for twentypenny nails and larger.

7. Nails generally should be driven no closer to

the edge of a piece than one-half its thickness and

no closer to the end than the thickness of tlie

piece. vSmaller nails can l)e driven closer to the

edges or ends than larger ones because they are

less likely to split the wood.

8. To decrease splitting, nails should be driven

in two or more rows whenever possible, or staggered slightly within the row when one row is used.

9. When nailing two pieces of lumber together

flatwise and at right angles to each other, nailing

patterns similar to those shown in figure 6 should

be used. These patterns should also be used when

nailing a piece of Imiiber flatwise to another or to

the face of a larger frame member. The patterns

are adaptable to both fabrication and assembly

nailing.

-EDGE MEMBER

^STRUTS AND

DIAGONALS

-CROSSING MEMBERS

it

i~i

,ri7

ptii

T-

£i

OR GREATER

Figure 6.—Typical nailing patterns in open crates: A, Nailing

for assembly of panels to each other; B, nailing For fabrication

of panels, as used to nail floorboards to skids and lumber

sheathing to frame members.

10. When nailing plywood to struts or other

members in fabrication (fig. 7), nails should be

spaced not more than 3 inches on center and

staggered in rows not less than % inch apart. The

farther apart the rows, the greater the racking

resistance of the joint.

11. When attaching two members so their

grain is parallel, such as sheathing to struts, the

number of rows of nails is usually determined by

the width of the surface in contact. One row of

nails is used for widths of 2 inches and less, two

rows for widths over 2 inches and less than 6

inches, and three rows for widths 6 inches and over.

12. When nailing a 1-inch-thick frame member

flatwise to a 2-inch-thick member to form a

laminated beam or similar combination, sevenpenny nails are used with the heads placed in the

thinner member. Two rows are used for 4- and

6-inch pieces and three rows for wider pieces.

The nails are spaced about 16 inches apart in the

rows. Stagger them between rows. Longer nails

may be used and clinched about % to K ii^^^^-

Nails should be about 1 inch from the edges.
WOOD CRATE DESIGN MANUAL 19

USE 2 ROWS OF NAILS FOR

MEMBERS TO 4" WIDE AND

3 ROWS FOR 6" AND

WIDER MEMBERS

2" 2"2"

ï

-6 -^

UPPER

FRAME

MEMBER

a

"1

6"

I o o o

1/2 MINIMUM

"lo

§1

^^

1*^ HORIZONTAL

BRACE:

1° ~o ^" Ô~ S

_PLYWOOD JOINTDOUBLE NAIL

Figure 7.—Typical nailing patterns for fastening plywood

sfieathing to frame members.

13. When nailing two 2-inch-thick members

together flatwise, as for laminated joists or beams,

twelvepenny nails should be used. Nails are

placed 1 to 1}^ inches from the edges of the members, depending on their width, and approximately

16 inches apart in the rows. Two rows of nails

should be used for members 4 to 6 inches wide

and three rows for wider members. Nails in each

row are driven alternately from opposite sides of

the pieces and staggered between rows.

14. When three 2-inch-thick pieces of lumber

are to be nailed together, first two pieces are

nailed together with twelvepenny nails spaced

and located as described in rule 13, except that

all nails are driven from the same side. The

third piece should be nailed with twelvepenny

nails to the piece that contains the nail points.

The nails are spaced about midway between the

points of the first nails.

15. In fabrication of lumber-sheathed crate

panels, at least two nails should be driven through

each sheathing board into each member it crosses.

In assembly, also, at least two nails should be used

to fasten each sheathing board to each fastening

member, including skids.

16. When two pieces of plywood sheathing are

butt-jointed, the joints should be positioned at

the center of a vertical or horizontal frame member. The abutting edge of each sheet of plywood

is nailed with two row^s of clinched nails, and the

nails arc s(agg(U'ed between rows.

Lag Screws

Lag screws are most commonly used in crate

construction for assembly of the panels, particularly in fastening sides and ends to the base.

Their use allows the crate to be fully or partially

demountable. Lag screws have excellent directwithdrawal and lateral resistance and are often

used in crates where high stresses occur in handling.

Two t^^pes of lag screws are commonl}^ used:

(1) The cut lag screw, which has a thread diameter

the same size as the shank; and (2) the rolled or

pressed lag screw, the threaded portion being

larger in diameter than the shank. The cut lag

screw^ is perhaps the most common type used in

crate assembly. Lag screws used in crate construction vary from ){ to % inch in diameter and

are from 2 to 6 inches long. The threaded portion

covers about two-thirds of the length in these

sizes.

The lateral and withdrawal resistance of a lag

screw depends principally on the contact of the

lag screw threads with the wood. Lead holes

are drilled before lag screws are started, and the

size of these holes is important to insure maximum

contact without splitting the wood (fig. 8).

Figure 8.—A, Lag screw lead hole of proper size results in

deep thread penetration and maximum resistance to withdrawal,- ß, an oversized lead hole results in shallow penetration of lag screw thread and poor withdrawal resistance.

Drill the entry hole, the same diameter as the

shank, through tlie member or assembly to be

fastened. The size of the lead hole in the receiving

member varies and depends on the density of the
20 AGRICULTURE HANDBOOK 2 5 2, U.S. DEPT. OF AGRICULTURE

wood as well as the outside diameter of the lag

screw at the threads. The eonibined depth of the

entry and lead holes should equal the total lent^th

of the shank and threaded portions. The size

of the lead hole for lag screws should follow the

recommendations in table 10.

TABLE 10.—Diameters of lead holes and I) values

for variou^^ sizes of lag screws

Lead hole diam- Values

Lag eter in wood of

screw

diameter

Groups Group D D2 D3/4

I, II, III IV

In. in. In. In. In. In.

Vi Vie Ke 0. 250 0. 0625 0. 354

Vu % K . 3125 . 0975 . 418

% % Me . 375 . 1406 . 479

'/ % }U .500 . 2500 . 595

% y» 1/ /2 . 625 . 3906 . 703

% '.', % . 750 . 5625 . 806

Direct-mithdrawal resistance.—Penetration of the

threaded portion of about 7 times the shank

diameter in the denser species and 10 to 12 times

in the softer species will develop approximately

the ultimate tensile strength of the screw in

direct withdrawal.

The allowable load for lag screws in direct withdrawal from the side grain of seasoned wood may

be determined from the following formula:

P= 1,800 G^'^ D3/4

where P is allowable load in pounds per Inieal inch

of penetration of the threaded portion of the lag

screw into the member receiving the point; D is

shank diameter of the lag screw in inches; and G

IS specific gravity of ovendry wood (table 6).

For convenience of the crate designer, table 10

covers the sizes of lag screws that might be used

m the formula.

Lateral resistance.—k][o\\dihh loads for lateral

resistance are ordinarily based on a minimum

penetration of the threaded portion of the lag

screw into the main member. This penetration

varies from 11 times the shank diameter for the

?^ f ^^^^^ds to 7 times the shank diameter for

the harder woods. The assumed thickness of the

side member is 3.5 times the shank diameter of

the lag screw, and the length of the shank is

assumed to be equal to the thickness of the side

member.

1 7^\ .equations for computing the allowable

lateral loads in pounds, parallel to grain, for lag

screws screwed into side gram of various species

Species Formula

White-cedar, white fir, eastern P= 1,800 D^

hen dock, soft pines, spruce,

ot her species of similar density.

Aspen, basswood, cottonwood, P=2,040 Z>^

Douglas-fir (mountain), western hemlock, redwoods, yellowpoplar, other species of similar

density.

Black ash, soft elm, gum, larch, P=:2,280 D^

soft maple, Douglas-fir (coast),

southern yellow pine, other

species of similar density.

White ash, beech, birch, rock

elm, hickory, hard maple, oaks,

other species of similar density.

P=2,640 D'

P equals allowable load per lag screw in pounds.

D is shank diameter of the lag screw in inches.

Allowable lateral loads perpendicular to grain

are somewhat lower. This reduction factor varies

from 85 percent for Ke-inch-diameter lag screws to

60 percent for ^s-inch-diameter lag screws.

Rules for use.—The following general methods

will aid the crate builder in properly placing and

using lag screws :

1. A plain flat washer or other reinforcing device

should be used under the head of each lag screw.

The washer prevents the lag screw head from

cutting into the wood and reinforces the area

around the entry point.

2. To obtain good withdrawal resistance, a lead

hole for the threaded portion of each lag screw

should be drilled according to the sizes shown in

table 10. The entry hole should be the same

diameter as the shank. One method consists of

drilling the shank entry holes in the prefabricated

panels during construction and the lead holes for

the threaded portion during assembly. A spHtshank countersink, when available, allows the

lead and entry holes to be drilled in one operation.

3. Lag screws should be turned the full distance

into their holes. Partial driving strips the wood

threads and reduces the holding capacity of the

lag screws. If the wood threads are stripped the

lag screw should be placed in a new location. A

power impact tool will turn lag screws in quickly

and uniformly.

4. Lag screws should not be countersunk.

Countersinking reduces the cross section of the

first member entered and weakens the joint.

5. The required number of lag screws to fasten

the sides of a crate to the base is determined by

dividing the gross weight of crate and contents by

the allowable lateral load per lag screw.

6. The size of lag screw is selected on the basis

of the size of the skid or fastening member used.

Lag screws X or %6 inch in diameter are used for
WOOD CRATE DESIGN MANUAL 21

small crates with 2-iiich-thick members; %-inch

lag screws for 3-inch-thick members; M-incli lagscrews for 4-inch-deep skids; and %-incli and

larger lag screws for 6-inch and deeper skids.

Bolts

Bolts are used in various phases of crate construction, and the type selected should be governed

by the location in the crate. Machine bolts are

often used in the blocking and bracing phases of

packaging, where they are especially useful in

anchoring the contents to the base. Any bolt

that may be removed occasionally should be a

machine bolt, so that both ends umy be fitted

with a wrench. On the other hand, bolts that

will not have to be removed preferably should be

carriage or step bolts. Carriage and step bolts

are used to fasten the heavier end headers and

floorboards to the skids. Both carriage and step

bolts are so designed that no washer is required

under the head. Furthermore, these bolts can

be placed head side down in a skid and cause no

interference in skidding because the shape of the

head prevents snagging.

Occasionally it is desirable to use a removable

bolt where its nut would be inaccessible with

a wrench. Available for such cases are special

bolt-nut combinations, sometimes called barrel

bolts, in which the nut is fastened in the end of a

sleeve. The sleeve is placed in a predrilled hole

in a block or skid, and the bolt engages the nut

through the sleeve. For these bolts the holes

must be located accurately so that no difficulty

occurs in assembly.

In some types of construction, such as the wood

truss, bolts are in double shear—used with three

members. Ordinarily the stress in the outside

two members is in one direction and the stress

in the center member is in another direction.

In crate construction where bolts are used to

fasten the side panel to the skid of the base, the

bolts are in single shear rather than double.

Load values for bolts in single shear are ordinarily only sKghtly greater than the lateral

resistance loads described for lag screws. The

equations and other data in the preceding section

may apply for bolts of equal diameter. " Specific

load values for different bolt diameters and species

of wood may be obtained in National Design

Specifications.*

In order to obtain full design strength, the

apphcation of bolts is important. Holes of the

same diameter as the shanks of the bolts should

be prebored. A hole so small that the bolt

must be driven forcibly may mean the wood

will be split. Plain washers should be used under

/National Lumber Manufacturers Association. National design specifications for stress-grade lumber and

Its fastenings. 64 pp., illus. 1962.

the nuts of all types of bolts and under the heads

of machine bolts. After tightening the nut,

paint the threads projecting beyond it with unthinned lead paint, or use another locking device to prevent the nut from turning.

The heads of all bolts should be on the outside

of crates. They are less likely to cause interference than the nut ends. This is especially

true on the underside of skids, where the round

head of the carriage or step bolt causes no troubles

during skidding. Countersinking bolts reduces

the cross section and strength of the member.

When a reusable crate is designed, nut-sleeve

and bolt combinations instead of lag screws

are often desirable to fasten the sides and ends

to the base. This method of assembly will

allow the crate to be reused a number of times

without loss of holding power. The spacing

should be the same as used for lag screws.

The following methods are recommended in

the use of bolts:

1. Carriage or step bolts should be used, head

down, to fasten the skids to cross members.

2. Boltholes should be drilled the same diameter

as the bolt shank. Place washers under all nuts

and under the heads of machine bolts.

3. Turning or loosening of the nut due to vibration should be prevented with a heavy lock washer,

a lock nut, or a double nut, or by painting the

thread beyond the nut with unthinned white lead

or similar material.

4. At least one bolt should be used at the end of

each end header and other members over 2 inches

thick that are not more than 4 inches wide, and

two bolts for members over 4 inches wide. Where

intermediate skids are used, end headers and

load-bearing floorboards should also be bolted to

them.

Timber Connectors

Connectors consist generally of metal rings or

plates that are embedded partly in two adjacent

members. These connectors transmit the shear

loads from one member to the other with an action

similar to a dowel or a key.

Most adaptable to crate assembly are the connector plate and the toothed-ring connector shown

in figure 9. They are pressed into each member

by turning the bolt or lag screw at the center of the

connector. (The lag screws used with connectors

should have cut threads rather than pressed

threads. Their penetration into the receiving

member should be from five to nine times the

diameter of the shank.)

Tables and formulas in the Wood Handbook ^

may be consulted to determine the allowable loads

for the toothed-ring and other types of connectors.

5 See footnote 1, p. 5
22 AGRICULTURE HANDBOOK 252, U.S. DEPT. OF AGRICULTURE

B

M-l 19666

Figure 9.—Types of connectors for heavy crates: A, Connector

plate/ B, toothed-ring connector.

However, it is generally assumed that a safe load

to assign to a 2-in('h connector is about twice

the safe load of a lao- screw alone.

The most logical use for connectors is in the

assembly of the sides to the base and top of very

heavy sheathed and open crates. In tliis use they

replace the lag screw connections that are ordinarily used for assembly.

Wood Screws

Wood screws may be used as a substitute for

nails where demountability is desired in lightweight

crates. They may also be used where pfyw^ood or

metal gusset plates must be fastenecí to thin

members in blocking and bracing, and nails are

not practical. Depending on their size and length,

screws usually have a higher withdrawal resistance

than nails. Because screws are not a common

means of fastening in crates, design data are not

included here. The Wood Handbook contains

design data for screws.

Adhesives

Although adhesives are not commonly used in

crate construction, they are sometimes used in

conjunction with nails for small, reusable plywood

containers. The nails apply pressure on the glue

until it has set and are left in place. Where moisture content of the wood is not controlled the

appUcation of glue has not been successful. Most

glues dry slowly without heat and require some

pressure during*^ drying. However, advances are

being made in adhesives research, and it appears

possible that contact and fast setting adhesives

will be developed for use in certain phases of

crate construction.

Steel Strapping

Steel reinforcing strap is commonly used on

sheathed crates that are intended for export shipment. Its major purpose, in most styles of crates,

is to reinforce the nailed corners and edges (fig. 10).

It is seldom used for crates with lag screw assembly except when they contain very heavy loads.

The corners and edges of open crates might also

be reinforced with strapping if loads are extremely

heavy or severe handling is anticipated. However, because open crates are most often used for

domestic shipments, the strapping is not usually

required. Certain types of strapping may be used

as bracing or hold-down strapping for the item.

Two general types of steel strapping, nailless

and nail-on, are suitable for use on crates. Nailless strap is a tension strap, applied with a tension

tool and sealed with metal crimp-on seals. It

must encircle the container or, on most crates, be

fastened to anchor plates on each side and tensioned to fasten the top in place. Nail-on strapping is annealed and may be nailed through the

strap, although it is more often prepunched.

Strapping is supplied with either a coated or

uncoated finish. When high resistance to rusting

is required, zinc-coated strap is recommended,

and the seals or nails used should also be rust

resistant.

Some of the points worthy of consideration in

appljang strap are:

(1) Each leg of the strap should be at least 6

to 8 inches long.

(2) For each leg three nails, preferably \){' to

1%-inch roofing nails, should be driven iK to 2

inches apart.

(3) Nailing should always be into a frame

member.

(4) Strapping and nails should be rust resistant.

(5) Corner strapping along edges should be

spaced about 36 inches apart.
WOOD CRATE DESIGN MAiNTUAL 23

TENSIONED

STRAPS

DOUBLE SEAL

1

SIDE

ii

STR,

1 m^^

A <

^

^

\

END,

LOCATE AT

' BRIDGING

.RUBBING STRIP^

Figure 10.—Strapping for crates: A, Sheathed crate with skid

base; B, additional strap for sill-type base.

(6) Tension strapping should be spaced a maximum of 5 feet apart.

(7) The tension strap should not be less than

% inch wide by 0.028 inch thick for gross loads

up to 10,000 pounds, and \)i inches mde by 0.025

inch thick for gross loads over 10,000 pounds.

Corner reinforcing strap (annealed) should not be

less than % inch wide by 0.028 inch thick for

gross loads up to 20,000 pounds, and \% inches

by 0.025 inch for gross loads over 20,000 pounds.

Certain types of strapping may also be used to

reinforce the sheathing where it is fastened to the

base with lag screws (fig. 11). This lag screwreinforcing strap increases the shear resistance of

the sheathing and results in greater lateral resistance for the lag screws.

LAG SCRE^ HOLE

CLOUT NAILS,

3/8" CLINCH (MIN.)

^ LAG SCREW STRAP

USE 2"BY 0,050"

ANNEALED STRAP

FOR 1/2" AND LARGER

LAG SCREWS

1-1/4" BY 0.035" FOR

3/8" LAG SCREW

LINE UP WITH CENTER

OF SKID

Figure 11.—Proper use of lag screw-refnforcing strap.

When the crate is assembled, the strap is alined

with the center of the skids and end header. Nails

are spaced IK to 2 inches apart and are clinched on

the outside face of the sheathing. One satisfactory method of using this strap is to predrill the

holes for the lag screws before the strap is placed

and nailed.

The strap should be \){ inches by 0.035 inch for

lag screws % inch or less in diameter. For lag

screws ){inch or more in diameter, the strap should

be a minimum of 2 inches by 0.050 inch.

DESIGNING CRATES

After considering the requirements and materials the crate designer next decides what size

the members should be, how to arrange them, and

other construction details.

Each component of a crate (base, sides, ends,

and top) has a definite function. The items or

contents are placed on the crate base, which sustains the load on sills or other load-bearino- members and transfers the load to the side panels.

The sides are assembled to the base and carry

the load of the base as well as resist the top load

superimposed by other containers stacked on the

crate. Ends of crates are crossties because they

tie the sides together, add racking resistance, and

are a safety factor for resisting top loads. The

top panel serves as a cover, a means of tying end
24 AGRICULTURE HANDBOOK 2 5 2, U.S. DEPT. OF AGRICULTURE

and side panels together, and also as a support for

top loading. Proper coinbination and fastening

together of these units or panels is necessary to

develop full strength of the erate.

IMPORTANCE OF DIAGONALS

Forest Products Laboratory research luis

brought out the importance of diagonal members

and their proper orientation and location. The

closer the angle of the diagonals witli respect to

the horizontal members is to 45°, the greater is

the racking resistance of the panel. When loads

are applied to the corners of open crates, the stress

in each member is dependent upon its length, as

well as upon the distance to the diagonally opposite

corner. The more nearl}^ a cube the crate l)ecoines,

the more even are the stresses in each member.

The ultimate in crate design is one in which all

the diagonals are at an angle of 45° to the other

members.

The following principles are important to the

crate designer:

1. Two diagonals crossing each other nuike each

panel considerably stronger than does a single

diagonal.

2. All faces of the crate should be braced with

diagonal members, unless the crated item can

resist torsional stress or is suspended freely in the

crate.

3. When all of the crate faces are braced and

the item is properly supported, racking of the contents cannot take place until the crate has failed.

4. If a crate has only five faces braced cUagonally

and is loaded on diagonally opposite corners or is

stressed by any method that allows distortion to

the unbraced face, all faces will twist very much

alike. However, the diagonal distortion will be

concentrated largely in the unbraced face and will

be many times that of the braced faces. When all

six faces are diagonally braced, both the twisting

and diagonal distortion are quite uniform throughout the crate.

5. When one or more faces of a crate are not

braced diagonally the contents can be racked

\vithout crate damage because of the extreme distortion in the unbraced face or faces.

Many times the contents of a large crate are

found to be damaged even though the crate itself

is apparently in good concUtion. In these

instances the crate was distorted, the contents

were damaged, and then the crate returned to its

normal shape.

DESIGN PRINCIPLES

Based on a mathematical analvsis of crate

members and panels, construction "^methods and

the sizes of members were determined for the

majority of crate types for both domestic and

overseas shipments. The crate analysis was then

verified by rough-handling and stacking tests of

crates l)uilt according to these criteria. This

information has been converted to tables and

plans for use by the designer. A discussion of the

theory and methods of analysis is presented here.

In a mathematical analysis of a crate many

components of the crate panels are included.

wStandard beam formulas are used to determine the

sizes of joists and load-bearing floorboards. Both

are calculated to span the width of the crate.

Even though floorboards are fastened to intermediate skids, because of certain methods of

handling the effective span must be considered as

the distance between the outside skids.

The sides and ends, as well as some members of

the base, are considered as parts of a bridge truss.

The sizes of members are determined by analyzing

tliis truss. The Howe truss, with its parallel

upper and lower chords and its vertical and

diagonal members, has the same general pattern

as the frame members of the side of a lumbersheathed crate (fig. 12). Since the truss is a

framed structure composed of straight members,

the stresses in the members due to loads must be

either compression or tension. The magnitude

and character of the stress in each member can be

determined by the graphic method. This involves

solving a series of stress diagrams of the triangles

that make up the truss, using T-square, triangles,

and scale. The sizes of the various members can

be determined by using equations based on stresses

found with the diagrams.

Figure 12.—Comparison of: A, Howe truss with parallel chords;

B, side panel of sheathed crate.

This method of analysis allows a skid member

to be considered as a part of the lower frame,

since sides are effectually fastened to the base at

assembly. Thus the skid sizes necessary are

greatly reduced. Designing the skids as beams

without considering the sides would result in
WOOD CRATE DESIGN MANUAL 25

-

/!/, M -^

X. ^ '

\X />«" 11

/X 1

L' \ :

/ X '

/ Xj

\ >

X /

\ K X/

•X

J \

/ \

E -1 \ c \

oo /,a\ B

OO

IpOO /,500

TRUSS DIAGRAM

MEMBER

TYPE OF

STRESS

STRESS IN

POUNDS

EG COMP. 2,100

GE TENS. 1,500

GH TENS. 1,500

HI COMP 700

!D TENS. 2,000

^—f

LOOO

f,o,n,m—-v

l,500

STRESS DIAGRAM

M-119665

Figure 13.—Truss and stress diagrams used to determine the magnitude and character of stress in each member of the side of a crate.
26 AGRICULTURE HANDBOOK 2 5 2, U.S. DEPT. OF AGRICULTURE

unnecessarily large members, with greater eost,

weight, and cubic displacement.

A timber truss is fabricated with bolts and

timber connectors. The sides and ends of crates

are held together by sheathing, joined to each

frame member by a series of clinched nails. This

panelized fabrication provides a strong, rigid

framework. When the sides are combined with

the base, ends, and top, the resulting trussed

structure can support a variety of loads.

Through the use of column formulas, the sides

of the (Täte are examined for adequacy to support

superimposed loads. This method also is

discussed.

Truss Diagram

The graphic method of solving for stresses in

members of sides of crates can be i)est illustrated

by a specific example. The truss diagram and

the stress diagram are used together for determining the character and magnitude of the stresses

in the crate members under a typical loading

condition. The upper diagram in figure 13 show^s

the side of a lumber-sheathed crate with its

diagonals, struts, and upper and lower longitudinal members. Directlv below the side panel

is a truss diagram—a line drawing scaled to be

identical with the centerline of each frame

member of the crate. The truss diagram shows

the crate supported at each end, as it is when the

crate is lifted WTth a pair of slings. The solid

lines indicate the members that are stressed under

these loading conditions, and the broken lines

are those for which no stress is considered. A

member is defined by the letters of the two areas

it separates. If the crate is supported at the

center by a single set of grabhooks or by a forklift

truck, the loading conditions are reversed.

It is assumed that the crate and contents

weigh 6,000 pounds. Half, or 3,000 pounds, is

carried by each side panel. Assuming uniforndv

distributed loading, the 3,000 pounds^ are evenlv

divided between the four panels of the side.

For ease of analysis, it is assumed that 1,000

pounds (dowmward forces) are assigned to each

of the three center panel points, with each end

supportmg 1,500 pounds (upward forces) as

shown in the truss diagram. The next step is to

assign a letter to eacîi area of the diagram as

shown, so that a force diagram can be outlined

lor each set of member intersections. A joint is

defined by the letters of the three or four areas

next to it.

Stress Diagram

The actual sti-ess diagi^am is started by laying

out to an appropriate scale (in pounds) alf vertical

torces represented l)y the vertical loadline c6, as

shown on the stress diagram (fig. I3j. Thus'the

reactions of 1,500 pounds each are 6/and aô, both

upward forces. The downward forces of 1,000

pounds each represented by he, cd, and de are

scaled and marked on the same vertical line as

shown. The total dowmward forces of 3,000

pounds now equal the total upward forces of

3,000 pounds.

A stress diagram may now be drawn for the

members FG and QE which intersect at the left

reaction point on the truss diagram. Clockwise

around the left reaction point are three forces:

EF (the reaction), a known upward force of

1,500 pounds; 7^(7 (the diagonal force) ; and GE

(the horizontal force). FG and GE are of unknown magnitude. Because these forces are in

equilibrium, the lines in the stress diagram corresponding to the forces must meet. Therefore,

moving to the vertical load line of the stress

diagram and starting at point e, there is an upward force of 1,500 pounds to point f. From/ a

line is drawn down and to the left diagonally

which is exactly parallel to member FG on the

truss diagram. Since the diagram must close, a

horizontal line drawn on the stress diagram from

point e and parallel to GE on the truss diagram to

the intersection of the diagonal line wiU form

point g. This will close the triangle and solve

the stress diagram for the intersection. The

result is a triangle composed of lines ej, fg, and

ge. The magnitude of the stress designated by

efis known (1,500 pounds). By scaling the length

of lines, the magnitude of the stress/^ is found to

be 2,100 pounds; ge, 1,500 pounds.

The next stress diagram to be developed is one

at the intersection of members GH, HI, ID, and

EG. The magnitudes of the stresses at this

intersection are determined in the same manner.

Thus gh (1,500 pounds), hi (700 pounds), and

id (2,000 pounds) are determined by progressing

clockwise around the joint. The entire stress

diagram is then drawn by solving each of the

other six intersections.

The magnitude of the stress in each member

is known, so the character of stress (compression

shown as + or tension as — ) must be found.

For example, to determine the character of the

stresses at the first joint examined (left reaction

point), both the truss diagram and the stress

diagram must be referred to. Using the clockwise system in the truss diagram for member

FG and proceeding from / to g, the direction of

the line in the stress diagram is downward and

to the left. This direction is then transferred

to the truss diagram on member FG and a small

arrow placed on this line toward the joint or

reference point. The member is indicated as

in compression with +, since forces toward the

joint produce compression stresses in the member.

Similarly, for the GE member, the ge line direction

is to the right; when transferred to the truss

diagram, it is away from the reference point and
WOOD CRATE DESIGN MANUAL 27

the member is in tension, shown by —. The

character of stress in each member in the truss is

then determined in a hke manner. The information on the magnitude and character of

stresses in the members may be placed in a

table for the convenience of the crate designer.

These stresses were used in determining the size

of members required under the loading conditions

outlined.

Determining Size of Members

The next phase in the analysis is to determine

the sizes of members based on the magnitudes of

the stresses found by developing the stress diagram. Inasmuch as there are both compression

and tension stresses in the various members, working stresses for each kind must be selected, allowing

for most general conditions.

Tension members.—The required size of all

tension members in the truss is determined by the

formula

-? (1)

where A is the required cross sectional area of the

member in square inches, P equals total load in

pounds (from stress diagram), and/is the working

stress in pounds per square inch (in tension parallel

to grain).

For example, the magnitude of stress in a tension

member is 5,500 pounds, which has been determined from solution of a stress diagram, similar to

the one shown in figure 13. The working stress

for the species used is assumed to be 1,000 pounds

per square inch. Then the net cross sectional

area required is

=5.5 square inches .^P_5,500

/""i,ooo'

The net area of a nominal 2- by 4-inch member

(actually 1% by 3% inches) is approximately 5.9

square inches. Therefore, a 2 by 4 is satisfactory.

Compression members.—With supports at each

end as in the truss diagram (fig. 13), the major

stresses in the struts and lower frame members

are tension stresses and those in the diagonals and

upper frame members are compression stresses.

Therefore, the compression members (diagonals

and upper frame members) must be designed as

columns and the column formulas used to determine their sizes.

The slenderness ratio -j (length of member in

inches divided by the least dimension) of each

compression member must be calculated in order

to decide which column formula to use. The

effective thickness (or at least dimension) for computing -7 is based on the assumption that the

thickness of the sheathing is added to the thickness

of the frame member. L is equal to the length of

each member in inches of clear span (distance between its intersection with other members).

For example, assume the actual least dimension

of the member to be 1% inches, to which is added

the thickness of the sheathing, % inch, for a total

d of 2.375. Assume the length to be 24 inches,

then the slenderness ratio is

24

d 2.375 ao.i

Short columns.—Usually a short column is one

that has an -r ratio of 11 or less. Bending is not

considered in calculating its capacity to carry

loads, and the full safe unit compression stress

may be used. Therefore, the formula used to

determine the capacities of short columns is as

follows:

(2)

where A represents the required area of the member in square inches, P is total load in pounds

(from stress diagram), and c equals working stress

in pounds per square inch (compression parallel

to grain). Thus the size of members can be

calculated directly using the full safe unit compressive stress and the total load.

Intermediate columns.—Intermediate columns

are usually considered as those that have an -^

ratio over 11 but less than the value of K. The

value of K is sometimes considered as 22.4, but

the method used to determine this factor is also

included. The recommended formula for use

under these conditions is as follows:

P

A^ b-mi (3)

where P equals total magnitude of stress in pounds,

A is required net area in square inches, c is safe

unit compressive stress in pounds per square inch,

L is unsupported length or height of member in

inches, d is least dimension in inches, and K is

approximately 22.4.

For an exact value of K, use the formula:

K=O.M ^ (4)

where /Í represents modulus of elasticity (in

pounds per square inch) for the species used.

As an example of determining the size of a

single compression member with an -^ ratio be-
28 AGRICULTURE HANDBOOK 2 5 2, U.S. DEPT. OF AGRICULTURE

tween 11 and 22.4, assume /' is 5,500 pounds, c

equals 1,000 pounds per square inch, L nqjresents

35 inches, d is \% inches, and E equals 1,2()0,0()()

pounds per square inch:

,000 .99 9

Then

or

A 5,500 ^ ^ . . A= '^ ^7.8 square inches /05

Therefore, use a 2- by 6-inch member, which has

the closest net area, 8.9 square inches.

If sheathing- thickness is included in the least

dimension, the value for d increases accordingly^

and more than likely a smaller member than a

2 by 6 will be required.

Long columns.—For columns with -j ratios equal

to i^or greater the Euler formula with a reduction

factor of 3 is used. This formula is as follows:

Ordinarily the slenderness ratio (f) "^ "

(5)

solid

wood column should not exceed 50. In crate

construction, when it does, with the combined

thickness of 2-inch members and sheathing, the

unsupported length must be decreased. This may

mean spacing the struts closer together for upper

frame members, or adding an intermediate longitudinal member in the side for diagonals.

An example in the use of the column formula

for long columns is:

Assume P=:3,000 pounds; £"=1,200,000 pounds

per square inch; i= 80 inches; and d^l% plus

3/ ^ f^^^ ' 1 .• T. . .. ,.,

/4 =2.375 inches (includes sheathing thickness).

The ^ ratio would then be ^^-^—=

d 2.375 =33.7, which is

within the limits of the formula for lone; columns.

Then

P 0.274:E

A

(^;

or

3,000__ 0.274>a,200,000

/_so_Y

\2.375/

or

A=' ' =10.3 square inches

'I'hus, a 2- by 8-inch member with a net area of

12.2 square inches would be satisfactory.

While the thickness of the sheathing is considered in determining the -^ ratio, it should not

be included in selecting the net area of the member. The sheathing is considered when determining the ability of the crate to support top

loads and will be discussed later.

Selection oj sizes.—The previously listed formulas based on the graphic method will determine

the sizes of the members in the sides of a crate

needed to meet stresses imposed by the weight of

the crate and the contents. However, in crate

construction it is practical to use struts that are

all the same size. For example, if several struts

require 2 by 4 areas and others 1 by 4, it is usual

to use 2 by 4's for aU struts. Likewise all diagonals should be the same size. Because of fabrication methods they should be the same thickness

as the struts. The upper and lower frame members are in one piece, except in long crates, where

the frame members are securely spliced. Consequently, these frame members should be of a

uniform cross section for their entire length, with

the greatest stress or size as the controlling factor

for the entire length. In designing the lower

frame members, 75 percent of the tension value

of the skid is subtracted from the stress to be met,

and the lower frame member designed to meet

the remainder of the stress.

After the sizes of the frame members have been

determined for the conditions outlined, they must

be examined to determine their capacit}^ for

superimposed loads. These loads depend on the

size of the crate. The wider the crate becomes, the

greater the superimposed load might be. The

width of the crate affects not only the design of

the top and base, but also the struts in the sides and

ends. So all struts should be checked as columns

to carry a possible superimposed load of from 200

to 400 pounds per square foot of crate top. Because of these superimposed loads, 1-inch-thick

struts are usually limited to heights between 8 and

10 feet, except on very narrow crates where the

superimposed loads could not become very great

per strut. The same column formulas previously

listed (2), (3), (4), and (5), should be used for

these calculations.

In stacking sample crates of like size, stacking

heights of from 25 to 60 feet were achieved before

loads reached 200 pounds per square foot. It is

reasonable to assume, however, that in extremely

heavy crates sides and ends must often be designed to support as much as 400 pounds per

square foot. Knowing the conditions to which

the crate will be subjected, the crate designer can

select the top load in his calculations.
WOOD CRATE DESIGN MANUAL 29

DESIGNING THE CRATE BASE

The skid-type base for most crates, whether open

or sheathed, consists of longitudinal skids with

end headers and other cross members. These

cross members may consist of load-bearing floorboards (to carry loads across to the skids), forklift

headers, diagonals for racking resistance, and

flooring of various types. The heavier members

are bolted to the skids; lighter members and the

flooring are then nailed to the skids to form a rigid

unit suitable for mounting almost any type of

item. Sill bases are made up of members placed

on edge and framed to form a structural system.

These bases are also considered in the design

analysis.

Skids

In designing a crate, it is assumed that a large

part of the load imposed by the contents is carried

by the side panels acting as trusses. Therefore,

large skids are not necessary as load-carrying

members because the sides act integrally with the

skids in this function. While this assumption results in smaller size skids, it does not permit

handling and moving a loaded base alone without

the sides and ends fastened in place. If the base is

to be moved with the item in place, the skids must

carry the entire load when lifted b}^ slings from the

ends. The skids must then be computed as

beams, which results in much larger sizes. The

siz3 of skids under these conditions depends on the

location of the load with respect to the length of

the skids and somewhat upon the kind of load.

Some items are amply rigid to be lifted without

much aid from the skids.

Flexure formidas for timber beams can be used

to determine the size of skids required for a

loaded base to be moved and handled \vithout the

sides in place. The size can be determined for

either a uniforml}^ distributed load or a concentrated load.

In designing a beam for flexure, the maximum

bending moment may be computed from the

following formulas :

Wl M=-~ (for uniform load)

o

(6)

or

Wl M=-— (for load concentrated at conter of span)

(7)

where M is the maximum bending moment, W is

total load on beam in pounds, and I is length in

feet. This results in a moment measured in footpounds that can be changed to inch-pounds by

multiplying by 12.

•The flexure formula is then used to compute the

section modulus of the beam as follows :

M

f

=S (8)

where S is section modulus and / is safe extreme

fiber stress in bending.

The crate designer should decide the value of/,

which varies with species, moisture content,

duration of load, and so forth, from 1,000 to 1,600

pounds per square inch or more. Methods of

determining working stresses have been described

(p. 10).

The section modulus, S, is equal to the moment

of inertia, /, divided by c (distance of fiber farthest

from neutral axis), or

S=/

For rectangular, sections such as skids, loadbearing floor members, and joists:

c ' 6

where b is total width of the beam and d is depth

of the beam. The section modulus formula would

then be

S=bd'

(9)

From formulas (6) or (7), (8), and (9), the total

width of the skids can be determined when they

are designed as beams for handling the loaded base

without aid from the side and end panels.

The following example illustrates the method of

determining the size of skids when they are

designed as beams :

At a skid length of 10 feet, a total uniformly

distributed load of 5,000 pounds, and a working

stress of 1,200 pounds per square inch.

M- iy/_5,000X10_6,250 foot-pounds or

8 8 ~ 75,000 inch-pounds

M o 75,000 ^^ ^ . • • u

^=S or —^r—=62.5 cubic mches

^ / bd^ „^ _

S=- or —^=62.5

c 6

bd'=375

Assuming- the skids to be a nominal 6 inches deep,

375 375

or 5K inches effective depth, 6 =

d' 30.3' 12.4,

or a total width of about 12)^ inches. This

total width may be divided into two or more

skids, depending on the width of the base. The

skids should be selected from standard timber
30 AGRICULTURE HANDBOOK 2 5 2, U.S. DEPT. OF AGRICULTURE

sizes. It is usual to select skid sizes that result

in shapes no greater in depth than IK times the

width. When skids are too deep, they may tip

when the loaded base is pushed or moved.

The width, 6, may be assumed and the depth is

then solved in formula (9).

The flexure formulas are one of the accepted

methods of determining, without a consideration

for a minimum deflection, the size of a member

acting as a beam in bending. In the majority of

crate designs the deflection is not considered because strength is the main problem.

Sills

A sill base is a framework of load-bearing members called side, end, and intermediate sills. The

side sills are considered as lower frame members

of the sides, smiilar to the skids in a skid base.

When handling of the loaded sill base alone is

considered, the side sills should be computed as

beams and the flexure formulas used as described

for skids. Unless this additional strength is included in the design, the loaded sill base should

not be handled or moved without the side and end

panels in place.

The intermediate sills act as load-bearing members for the item and transfer the load to the side

sills. The sizes are determined by calculating

them as beams with uniformly distributed or concentrated loads as described for the sills. The

major difference is generall}^ the shape of the sills,

which are usually made up of 2-inch-thick material

and are 8, 10, or 12 inches deep, depending on the

load and span.

Included in the section on sheathed crates are

tables listing the allowable loads for various spans

of the sills. These tables usually serve the need

of the designer. They include average-density

lumber with those strength-reducing characteristics ordinarily allowed in load-bearing members.

The aUowable stress used was approximately 1,000

pounds per square inch. However, the use of

formulas may be worthwhile for denser lumber

with few strength-reducing factors. The size of

the intermediate siUs would then be determined

as shown in the following example:

Where span equals S feet, the load of 8,000

pounds is to be carried by two sets of intermediate

sills as a concentrated load, and a working stress

of 1,400 pounds per square inch. Then

jj-__E/_8,000y8_ 16,000 foot-pounds or

4 4 192,000 inch-pounds.

M_ 192,000 ^.^^ ^. . ^ T~ ~r4Ôcr"" cubic mches

c 6

Assume that two nominal 2-inch (actually 1.625)

inlermediale sills will be used at two locations for

a total of four. Then the total width 6 =6.5 inches

and

6.5

d=ll.2 inches

Use a total of four 2- by 12-inch intermediate sills.

Floorboards

The floorboards of a skid base help to frame the

base, serve as sheathing for it, and carry loads.

When used onh^ as sheathing or flooring the boards

usually are 1-inch material, but may be plywood.

Some crates are constructed with 2-inch-thick

floorboai'ds at each end of the base, which serve

to prevent damage from forklift handling. Concentrated loads often require heavy floorboards

that are fastened to the edge skids. Generally,

those floorboards that carry loads are called loadbearing floorboards and should be designed so that

the unsupported length is the clear distance between the edge skids.

Floorboards upon which the load rests are probably the most severely strained members of a crate

because of the increased stresses caused by impact

when a crate is handled roughly. Consequently,

even though they are bolted or nailed to the skids,

the load-bearing floorboards are computed as

simple beams, which results in slightly larger

members. This method of computing has been

proven by evaluations of loaded crates of many

weights and sizes at the Forest Products Laboratory. The floorboards were the most commonly

broken members. However, it should be remembered that under normal conditions a beam can

withstand a higher unit stress for a short time than

it can for an extended period of time.

Heavy items packed in crates may or may not

rest on a large area of the flooring, it is necessary

to determine how much of the flooring actually

carries the load, so that the load can be safely

transferred to the truss side of the crate at the edge

skids. This flooring, depending on how the load is

mounted, may even be one or more large members.

Safe loads for various thicknesses and spans have

beeil computed (table 11).

Size of the load-bearing floorboards is calculated

in the same manner as described for the skids and

the intermediate sills. It is first necessary to

solve for the bending moment, M, which depends

on the type of loading expected. The bending

moment for a concentrated load at midspan,

Wl . AI=——y is the most severe loading condition. A

uniformly distributed load Ai=-^^ is considered

o
WOOD CRATE DESIGN MANUAL 31

the least severe of the bending moments commonly

used in the design of beams. A third bending

Wl moment formula, M=—^ results in moment values midway between the concentrated and uniformly distributed loads.

TABLE 11.—Allowable load per inch of load-bearing

floorboard width with woods of groups I and II ^

Distance Allowable load when floorboard depth is—

between

outside

skids % inch 1% 2% ^Vs 5/2

inches inches inches inches

In. Lb, Lb. Lb. Lb. Lb.

12 47 220 574 1,095 2, 520

18 32 147 382 731 1,678

24 24 110 287 548 1,260

30 19 88 229 438 1,008

36 16 73 192 365 841

42 14 63 164 315 720

48 12 55 144 274 630

54 11 49 127 243 560

60 9 44 115 219 504

66 9 40 104 199 458

72 8 37 96 182 420

78 7 34 88 168 388

84 7 31 82 156 360

90 6 29 77 146 336

96 6 27 72 137 315

102 6 26 67 129 296

108 5 24 64 122 280

114 5 23 60 115 265

120 5 22 57 110 252

^ If woods of groups III or IV are used, these allowable

loads may be increased by 20 percent.

DESIGNING THE TOP

Two types of superimposed loads are carried by

crates: (1) smaller crates or boxes that result in

bending stresses in the top joists, and (2) other

crates of equal size that place most of the load on

sides and ends and very Uttle on the top joists.

The first type is often referred to as loading

without dunnage and the second type is with

dunnage or like-on-like loading.

The increase in like-on-like methods of stacking

large crates in storage has reduced the need for

high load assignments for joists. Crate tops designed for loads of 50 pounds per square foot have

proven satisfactory. The use of these lower design limits often results in a saving of 30 percent

in material for top panels. Other load assumptions used in designing tops have been as much as

100 to 175 pounds per square foot. The choice

of the hmits should generally be controlled by

transportation and storage conditions.

Joists are the structural members of the top

panel and have several functions. They carry the

692-318 0—64 3

loads imposed by placing small crates and boxes

on the top but not directly over the sides or ends.

In this case, the joists act as beams to support the

load and transfer it to the sides of the crate.

Another important function of the joists is to

resist pressures from sucli lifting devices as slings

or grabhooks, which place crushing pressures on

the sides near the top. Ordinarily joists resist

the lifting pressures when spaced evenly along the

crate length. However, it may be necessary to

add extra joists to heavy crates or to include joists

in very narrow crates that normally would not

have them.

In computing the size of joists required, it is

recognized that the top cross sheathing carries

part of the load. In fact, in narrow crates with

moderate top loads, the crosswise sheathing often

is suiîîcient without joists. However, the sheathing must be full length and have a solid bearing on

the side panels. The sizes of the joists are found

with the various beam formulas described in the

preceding section on base design.

An example of the design of a joist system for

the top panel of a crate follows.

Assume that the crate top is uniformly loaded

and will have nominal 1-inch sheathing placed

across its width, all pieces of full length. Also

assume that the width (span) of the crate is 8 feet,

the design load is 100 pounds per square foot, the

joists are placed 2 feet on center, and a safe unit

stress is 1,000 pounds per square inch. First, the

amount of load that can be assigned to the sheathing is found. Inasmuch as the joists will be placed

2 feet apart, the amount supported by a 24-inch

width of sheathing can first be determined.

Because the size of the sheathing is known,

the method of calculation is reversed from the

usual procedure.

^ I=bd' 24X0.75X0.75

o —— =2.25

c= 6

y=S orM=l,000X2.25=2,250

M=!î? or H'=?f§-*=187 pounds

The load assigned to the sheathing would be 187

pounds or about 12 pounds per square foot. This

would reduce the total load assigned to one joist

by 187 pounds, or 1,600-187= 1,413 pounds.

Then solving for the joist size

Wl 1,413X8X12 M= 8 8

= 16,956 inch-pounds

^^S=.^=17.0 cubic inches
32 AGRICULTURE HANDBOOK 2 5 2, U.S. DEPT. OF AGRICULTURE

S=- or -—-=^17.0

If the thicknes!

(1.625)

h(P=\02 square inches

h, of the joist is \% inches

(P= 102

=62.8 '1.625

f/ = 7.9 inches (required depth of joist)

A 2 by 8 joist is just under this size (7.5); so a

2- by 10-inch joist must be used, spaced 24 inches

on center.

Variations of spacin^i may be used to conserve

materials. Inasmuch as a 2 by 8 joist is shghtly

under the required size, the designer might change

the spacing of the joists so the 2 by 8 can be used.

The use of a denser species with a higher working

stress is another method of reducing the size of the

joist.

Manv open or partially sheathed crates have no

joists. In these and in fully sheathed crates that

do not have enough regular joists to resist grabhook pressure, it is necessary to use special joists.

These joists should be placed at the center of

bahmce of the loaded crate and their size determined l)y the width and weight of the crate. Very

long crates are often handled by more than one

pair of grabhooks, so more than one lifting joist

may he needed.

These reinforcing joists can be calculated by

use of the column formulas (2), (3), (4), and (5J.

For one set of grabhooks, the total weight of the

crate and contents should be used for P. For

two sets and two reinforcing joists, one-half the

total weight should be used for P.

Further information on the top construction of

sheathed crates, including joist sizes and spacings

for tops of various widths, is in the following

section.

SHEATHED CRATES

Sheathed crates may be used for packaging

items that require full protection by a closed container, for overseas or domestic shipment. They

may be sheathed with lumber (fig. 14) or with

plywood (fig. 15). For ease in describing their

requirements and characteristics, sheathed crates

are in three categories in this handbook: (1) the

mihtary type, for loads that do not exceed 30,000

pounds for either overseas or domestic shipment;

(2) the hmited-military type, for similar shipment

of loads of not over 2,000 pounds; and (3) the

light-duty type (fig. 16), for loads not over 1,000

pounds shipped by air anywhere or by surface

transportation witliin the United States.

MILITARY TYPE SHEATHED CRATES

Military type crates are intended for domestic

and overseas shipment of loads not exceeding

30,000 pounds of all kinds of manufactured

articles that require protection from the weather

and mechanical damage. They are designed to

withstand normal rough handling. Specifically,

the tops are designed to carry loads of 50 pounds

per square foot without dunnage. iSides of crates

containing items that weigh not more than 10,000

pounds are designed to resist top loads of 200

pounds per square foot with dunnage. Sides of

crates designed for loads over 10,000 pounds will

carry top loads of 400 pounds per square foot

with dunnage.

Member sizes are included in Appendix I for

crates up to 48 feet long, 10 feet wide, and 12

feet high. Both lumber- and plywood-sheathed

styles are included, as well as nailed (nondemountable) and bolted (demountable) assembhes.

Base Construction

The first part of the crate to be fabricated is the

base. Its size is usually determined by first

measuring the overall length and width of the

item to be crated. Add to these measurements

the desired clearances (from 1 to 3 inches) and the

thickness of the frame members of each end and

each side. The total of these measurements is

the size required for the base. Description and

details of the sill base (fig. 17) are included,

although the skid base (fig. 18) is most common.

Skid hase,—The skid-type base consists of

longitudinal skids that are assembled with such

cross members as headers, load-bearing floorboards, diagonals, and plywood or lumber flooring.
WOOD CRATE DESIGN MANUAL

HEADER

33

END FASTENING

MEMBER

LINER

END STRUT

LOWER FRAME MEMBER

END STRUT

GUSSET PLATE

HORIZONTAL

BRACE

DIAGONAL

LOWER FRAME MEMBER

FLOORBOARDS

END HEADER

LOAD- BEARING MEMBERS

SKID I^UBEING STRIP

Figure 14.-Exploded view of a lumber-sheothed crate designed for assembly with lag ,

END FRAME MEMBER

OR END STRUT

PLYWOOD FLOOR

LOWER FRAME MEMBER

PORKLIFT HEADER.

LOAD-BEARING MEMBERS

SKID RUBBING STRIP

HORIZONTAL

BRACE

LOWER FRAME MEMBER

Figure 15.—Exploded view of a plywood-sheathed crate to be assembled with nails
34 AGRICULTURE HANDBOOK 2 5 2, U.S. DEPT. OF AGRICULTURE

SKIDS

ASSEMBLY LAG SCREWS

Figure

M-119Ö64

16.—Light-duty type sheathed crate of cleated-panel

type.

The size of the skids required will depend on

the size of the load and the length of the crate:

Maxiynum

Maximum length of Minimum size

net load crate of skids

(pounds) (feet) (inches)

300 16 2 bv 4 (flat)

1,000 12 2 by 4 (flat)

2,000 20 3 by 3

10, 000 48 4 by 4

30, 000 32 4 b}^ 6 (on edge)

BOTTOM

SHEA THING

INTERMEDIATE SILLS

SIDE SILLSBRIDGING

END SILL RUBBING STRIP

Figure 17.—Sill-type base For crates.

When the width of the base is over 42 inches,

an intermediate skid is added to aid in forklift

handling from the sides of the crate. Four skids

are needed when the crate width is over 7 feet.

Size of end headers and diameter of bolts

depend on the skid size.

Skid size Header size Bolt diameter

(inches) (inches) (inch)

2 by 4

3 by 31

3 by 4/

In addition to headers at the ends of the crate,

headers may also be bolted to the skids 20 and

40 inches from each end for forklift handling.

Thus, the end and forklift headers serve to support

(inches)

2 by 4

3 by 3

4 bv 4

PLYWOOD FLOORING ^Q"

1/4 SPACE.

LUMBER ELOOPING

1/2" DRAINAGE

HOLES

EORKL IE T HEA DE PS

BOLT THROUGH

SKID-,

-7'^ NAILS

T BACK HEADERS

THICKNESS OE LOWER

FRAME MEMBER

THICKNESS OF

END SHEATHING

NOTCH MEMBERS THICKNESS

OF LOWER FRAME MEMBER

CARPI AGE BOL T

I" FLOOR BOARDS

SPACED FOR DRAINAGE

Figure 18.—Typical skid-type base for sheathed crate, showing both lumber and plywood flooring.

M-l 19670
WOOD CRATE DESIGN MANUAL 35

2-3

FIRST LAMINATION

TO FORM MEMBER

12^ NAILS

CARRIAGE BOLT

2"-3

30^ NAILS

SECOND ADDITIONAL

LAMINATION

M-119671

Figure 19.—Splicing and laminating: A, Splice of 4- by 4-inch

or 4- by 6-inch skid; B, splice of 2-inch member,- C, splice of

1-inch member; D, lamination of skid.

the crate on the forklift fingers and prevent

damage.

The load-bearing floorboards are selected on

the basis of the total load and the clear span

between outside skids. The sizes may be selected

from table 11.

Headers and heavy cross members over 2

inches thick are bolted to the skids with carriage

or step bolts. At the ends of these members space

IS left for the lower frame members, which rest

on the skid or flooring. The ends of the skids

extend beyond the end headers a distance equal

to the thickness of the end sheathing (fig. 18).

It is good practice, in bases with lumber sheathing,

^^.place the large cross members directly on the

skid. With plywood sheathing, however, the

large cross members are usually placed over the

plywood (fig. 18).

Lumber sheathing is nailed to the skids with

nailing patterns shown in figure 6. When the

floor covering is ph^wood, it should be nailed to

the skids with nailing patterns similar to those

shown in figure 7.

It is necessary to provide for drainage in the

floors of fully sheathed bases. Lumber sheathing

boards can be spaced about one-eighth inch apart

In plywood sheathing, }^inch holes should be

drifled at the corners of each section where water

might be trapped.

Rubbing strips are nailed to the bottoms of

the skids to provide for side forldift or end sling

handling. For small- or medium-size crates, a

nominal 2- by 3-inch or 2- by 4-inch strip is used.

For large, heavy crates it is well to use 3-inch-thick

strips for large-diameter sling cables and for

forklifts. End spacing for sHngs should be

provided as shown in figure 18. The ends of the

rubbing strips are full beveled at a 4,5"^ angle. Twoinch rubbing strips should be nailed to the skids

with two rows of twelvepenny nails staggered and

spaced about 12 inches apart in each row. Longer

nails are used for thicker rubbing strips.

In long crates, it is sometimes necessary to

splice the skids or to use laminated members when

single pieces of adequate length cannot be obtained. For greater strength, splices should not

be located in the center third of the crate. The

methods used for splicing and laminating are

shown in figure 19.

Sill base.—^The siU base is often used for items

that project below their support points, such as

rear axle assemblies or disassembled vehicles.

The load should always be transferred to the side

sills by intermediate sills with or without loadbearing headers, or by the article itself, so that

the side panels can aid in strengthening the base

(fig. 20). The sizes of the side and end sills for

various size bases should conform to table 12.

The sizes of intermediate siDs and load-bearing

headers should conform to table 13.

The base is fabricated by nailing the end sills

into the side sills and side sills into intermediate

sills. Bridging is used to prevent deep sills from

tipping. Metal hangers at each end of intermediate sills are securely nailed to the side sills.

These annealed steel straps carry most of the

load to the side sills. The flooring is nominal

1-inch boards when spans are less than 30 inches

between longitudinal members and 2-inch boards

when spans are 30 inches or more. The flooring

should be nailed to each crossing member with

nailing patterns similar to those shown in figure 6.

Rubbing strips are fastened under each longitudinal member (fig. 20).
36 AGRICULTURE HANDBOOK 25 2, U.S. DEPT. OF AGRICULTURE

BRIDGING

RUBBING

STRIP

INTERMEDIATE SILLS

SIDE SILL

/

VOIDS FOR

FORK LIFT

BOTTOM

SHEATHING

END SILL

METAL HANGERS

LOAD-BEARING

HEADER INTERMEDIATE SILL

/

RUBBING

STRIP

METAL HANGERS

SIDE SILL

BOTTOM

SHEATHING

END SILL

Figure 20.—Sill-type bases: A, wifh doubled sills; B, with load-bearing headers.
WOOD CRATE DESIGN MANUAL

TABLE 12.—Nominal size of side sills Jor crates over 3 feet high ^

37

Gross weight of crate

Nominal size when length of crate in feet is—

4 8 12 16 20 24 28 32

L6.

TID to 2 000 - -

In.

2 by 4

2 bv 4

2 by 4

2 bv 4

2 by 4

2 by 4

2 bv 4

2 bv 4

2 by 4

2 by 4

In.

2 by 4

2bv 4

2bV 4

In.

2 by 4

2bv 4

2 bV 4

2 bv 6

2 by 6

2 by 6

2bv8

2 bV 8

2 bV 8

2 bv 10

In.

2 bv 4

2 bV 4

2 by 6

2bv 6

2 by 6

2 by 8

2 bv 8

2 bV 8

2 bV 10

2 bV 10

In.

2 by 4

2 bV 6

2 bV 6

2 bv 6

2 by 8

2 by 8

2bv 8

2 bV 10

2 bv 10

2 bv 10

In.

2 bv 6

2 by 6

2 bV 6

2 by 8

2 by 8

2bv 8

2 bV 10

2 bv 10

2 bv 10

2 2 bV 8

In.

2 by 6

2 by 6

2 by 8

2 by 8

2 by 8

2 by 10

2 b> 10

2 by 10

2 2 by 8

2 2 by 8

In.

2 by 6

2 by 8

2 by 8

2 by 8

2 bv 10

2 001 to 4,000- -

4*001 to 6.000 -

6 001 to 8.000 -

8 001 to 10.000

10 001 to 12,000 2 by 10

2 by 10

2 2 by 8

2 2 by 8

2 2 by 8

12 001 to 14,000 --

14 001 to 16,000 - - -

16 001 to 18 000

18 001 to 20,000-

^ For heights of 3 feet or under, increase 2 by 4 sizes to 2 by 6; 2 by 6 sizes to 2 by 8; and 2 by 8 sizes to 2 by 10.

TABLE 13.—Allowable load for intermediate sills,

in pounds per inch of sill width, for ivoods of

groups I and II ^

Length

Allowable load when sill depth is—

of

sill

^1 CO.S O .S Z3 ^

Ft.

4

5

6

7

8

9

10

Lb.

55

44

37

31

28

24

22

Lb.

144

115

96

82

72

64

57

Lb.

274

219

183

157

137

122

110

Lb.

659

527

440

377

330

293

264

Lb.

1, 172

937

781

670

586

521

469

Lb.

1,880

1, 504

1, 254

1,074

940

836

752

Lb.

2,755

2, 204

1, 837

1,574

1, 378

1, 224

1, 102

The sizes of the upper and lower frame members,

struts, and diagonals are based on the loads to be

carried. Member sizes for crates containing net

loads up to 30,000 pounds are listed in Appendix I.

The end struts of the side panels receive nails or

lag screws in assembly and should be at least a

nominal 2 inches thick. Minimum end strut sizes

depend on the load and whether assembly is with

lag screws or nails :

Net load

(pounds)

1,000 or under

Over 1,000 but under 5,000-

5,000 or over

End strut size

Lag screw

assembly

(inches)

2 by 4

3 bV 3

4 bv 4

Nail

assembly

(inches)

2bv 4

2 by 4

2 by 4

^ If woods of groups III or IV are used, these allowable

loads may be increased by 20 percent.

Side Construction

The construction of sides for lumber- and plywood-sheathed crates (fig. 21) varies in the use of

diagonals and usually in the spacing of the struts

as well as in the type of sheathing. Usually both

types have the same size frame members and

struts. The plywood-sheathed crate does not

require diagonals or the paper liner that is ordinarily required for the lumber-sheathed crate.

The height of the side must include the heights

of the item, the base, and the top framing and top

joists, plus top clearance.

The arrangement of the frame members for

lumber-sheathed crates is usually based on the

height of the crate and should conform to figures

22 and 23.

The lumber sheathing for sides and ends should

be of nominal 1-inch material of square edge or

tongue-and-groove pattern. However, for net

loads less than 300 pounds, ^^inch sheathing may

be used.

In most types of sheathed crates, the sides are

made to support the top panel, which is designed

to carry top loads. In wide crates that carry

heavy top loads, the top framing is a system of

joists. The ends of the joists or the fastening

members are supported by the upper frame

members of the sides, which are at least 2 inches

thick, or by an extra strut placed under each joist

and fastened to the sides. Open crates, usually

not designed to carry heavy top loads, do not need

joists.

For sheathed crates assembled with nails, the

side sheathing usually has suflBcient thickness to

develop the full lateral resistance of the nails

along the skids. However, for heavy crates that

require lag screws, the sheathing, especially

pl3rwood, requires some reinforcing. This may

be done by adding a 1-inch fastening member or a

lag screw steel reinforcing strap to the bottom of
38 AGRICULTURE HANDBOOK 25 2, U.S. DEPT. OF AGRICULTURE

MINIMUM OF 3 NAILS

PER SHEATHING BOARDSTRUT

^DIAGONAL

- J NAILS (MIN.) PER

BOARD

^^INCH NAILS ON INSIDE

FACE OF FRAME MEMBERS

SHEATHING

-CLINCH ON FRAME

MEMBER SIDE

UPPER FRAME

MEMBER

USE 2 ROWS OF

NAILS FOR 4" WIDE

MEMBERS AND 3

ROWS FOR 6"AND

WIDER MEMBERS

PLYWOOD JOINT,

DOUBLE NAILED

STRUT

Figure 21 .—Fabrication of sides for sheathed crates: A, Lumber-sheathed side,- ß, plywood-sheathed side.

the side. The strap is nailed to the fastening area

of the side, and holes are drilled in the strap for

the lag screws (fig. 11).

Lumher-sheathed sides.—^The. sides are divided

mto panels of even widths by the vertical struts.

The spacing of these struts is such that the diao--

onals between form an angle as near 45^ as

possible. High crates may ^ have two or three

rows of panels, divided by the horizontal braces

(fig. 22).

The horizontal and vertical members are positioned with the diagonals between (fio-. 21 A)

Corrugated fasteners or staples are often used to

hold the frame members together while the

sheathing is nailed in place. A waterproof paper

is usually placed between square-edged sheathing

and frame members. Sheathing is nailed to the

frame members as shown in figure 21, A with

patterns as in figure 6. The placement and

clinching of nails should follow the general rules

(p. 17). The sheathing projects beyond the edge

struts a distance equal to the thickness of the edge

struts of the end. The projection of the sheathing

below the lower frame member should equal the

depth of (1) the skid, (2) the skid and flooring, or

(3) the side sills, in a sill-type crate. The pro-
WOOD CRATE DESIGN MANUAL 39

jmiCKNESS OF

FRAME MEMBER

OF END

STRAP

FLOOR BOARD THICKNESS

PLUS SKID THICKNESS

Figure 22.—Gafe sides of three heights with lumber panels.

jection of the sheathing at the top is equal to the

thickness of the top frame members or the depth

of the joists.

Plywood-sheathed sides.—The details in the

construction of plywood-sheathed sides (fig. 21, B)

and lumber-sheathed sides are much the same.

With plywood the need for diagonals and waterproof paper is eliminated, which usually lowers the

labor costs. Spacing the struts about 24 inches

apart makes it unnecessary to rip the width of the

plywood sheets. Odd-width panels may be located

at each end of the side or at the center. Joints

of the plywood are always made over the center of

a frame member. The projections meet the same

requirements as in lumber-sheathed sides. The

THICKNESS OF PLYWOOD PLUS THICKNESS

OF JOIST DEPTH OR FRAME MEMBER OF TOP

UPPER FRAME MEMBER-2 INCHES THICK

EXCEPT FOR CRATES LESS THAN 54"

WIDE OR WHEN VERTICAL JOIST SUPPORTS

ARE REQUIRED

END STRUT

NAILED-2 INCH THICK, SAME WIDTH

AS REGULAR STRUT

BOL TED-2"BY 4" THROUGH l,000 LB.

NET LOAD, 3"BY j" FOR OVER 1,000 LB.

THROUGH 5,000 LB. AND 4"BY 4" FOR

OVER 5,000 LB.

LOWER FRAME MEMBER •

SKID BASE SILL BASE

FLOOR THICKNESS DEPTH OF

PLUS DEPTH OF SfDE SILL

SKID

LAG SCREW STRAP-BOLTED CRATE

Figure 23.—Frame member arrangement of crate sides of both

lumber- and plywood-sheathed side panels.

placement and nailing of the members should

follow figures 7 and 21. The general nailing rules

(p. 17) should be followed. Horizontal braces to

reduce the effect of strut length are added according to crate height; the type of panels should

conform to figures 23 and 24.

Sizes of members and other details should be

the same as for lumber-sheathed sides. Member

sizes are listed in Appendix I.

Plywood sheathing for sides and ends should be

YA inch thick for net loads less than 300 pounds,

% inch thick for net loads not exceeding 10,000

pounds, and ]{inch thick for net loads over 10,000

pounds.

End Construction

The design for the ends of both lumber- and

plywood-sheathed crates is much the same as

for their sides (fig. 25). End panels are designed

to rest on the end extension of the skids or on the

end sills of sill-type bases. The bottom projection

of the sheathing in the ends of sheathed crates

will then correspond with the depth of skids or

sills (plus sheathing thickness when sheathing is

used under a header). The top projection corresponds to that of the sides or is equal to the

combined thickness of the framing members.

The sheathing at each side edge of the panel

should extend beyond the edge strut for the

thickness of the side sheathing. Spacing of struts,

diagonal location, size of members, placement of

reinforcing strap, and fabrication nailing are as

outlined for the side panels.
40

AGRICULTURE HANDBOOK 252, U.S. DEPT. OF AGRICULTURE

TOP PANEL

THICKNESS

LESS SHEATHING

— -"LI

~"C)

V ^

i\J >

ct ^

\

-\

JHICKNESS OE

ERA ME MEMBER

OE END

ANNEALED^ STRAP

(EOR BOLTED CRATE)

*-STRUT

\_FLOOR BOARD THICKNESS

PLUS SKID THICKNESS

STRUT

—\-THICKNESS OF ^STRAP |

'' FRAME MEMBER FLOOR BOARD THICKNESS

OF END PLUS SKID THICKNESS

Figure 24.—Side panels for plywood-sheathed crates of three

heights.

Sheathed crates require ventilation to prevent

moisture from accumulating and damaging the

packaged item. To insure air movement, ventilators can best be located near the top in the end

panels, and, in long crates, also in the side panels.

Because of the tight construction of a plywoodsheathed crate, more ventilating area is required

than in a lumber-sheathed crate. Tests have

indicated that a lumber-sheathed crate should

THICKNESS OF

SIDE PANEL

SHEATHING-A

DIAGONAL

LINER

VPANEL LENGTHA

'i I I I I I I I I I

THICKNESS OF^

SIDE PANEL

SHEA THING

HORIZONTAL

BRACE

l"BY 4" OR 2" BY 4"

GUSSET PLATE

METAL STRAP

UPPER FRAME MEMBER

HORIZONTAL

BRACE

I"BY 4" OR 2" BY 4"

METAL STRAP

i/4" PLYWOOD OR m

METAL BAFFLE

u

i.\

3/4 HOLES FOR

LUMBER SHEATHING

M-l 19675

Figure 25.—Ends for sheathed crates: A, Lumber sheathed/ ß,

plywood sheathed; Q, ventilation for ends of lumber-sheathed

crates.

have in each end panel at least one ventilation

hole three-fourths inch in diameter for each 45

cubic feet of crate volume. Details of vents and

baffling for a lumber-sheathed crate are shown m

figure 25, C j i f i

Plywood crates require in each end at least i

square inch of ventilating area for each 15 cubic

feet of crate volame. The vent for a plywoodsheathed crate should be a horizontal slot with

screening and a baffle. Additional cross members

reinforce the sheathing around large vents.

Lumber-sheathed ends.—End panels are constructed as shown in figure 26. Frame members

are the same size as those listed m AppendLx i

for the sides. For narrow ends, not over öO

inches wide, single diagonals may be used m

place of crossed diagonals.

Plywood-sheathed ends.—The end panels ot plywood-sheathed crates are constructed as shown m

figure 27. Frame members are the same size as

shown in Appendix I for the sides.
WOOD CRATE DESIGN MANUAL

TOP PANEL THICKNESS

LESS SHEATHING

UPPER FRAME MEMBER

STRUT—-^-

LOWER FRAME MEMBER

Q) ^

- ^

^ <s'^

^\i C^

O

QJK I

HORIZONTAL

r-BRACE

THICKNESS OF

SIDE PANEL

SHEATHING

u

LINER.

yPANEL LENGTHA ,"QY 4" OR 2" BY 4"

—I—I—I—I—I—t—I—1—1—I '. -, -. ,-

5 -

I

o

:^^^^>c^ ^

Q-

•î- k.

V)^J[ . Vi

VPANEL LENGTHA

METAL STRAP

(BOLTED CRATE)

PLYWOOD

GUSSET FOR l"

FRAME MEMBERS

§ ^

THICKNESS OF END HEADER

'(ADD THICKNESS OF PLYWOOD

FLOORING WHEN USED)

M-l 19694

Figure 26.—End panels for lumber-sheafhed crates of fhree

heights.

Top Construction

The tops of sheathed crates are ordinarily

designed to carry other crates or boxes durino;

shipping and storage. These top loads may vary

Irom 50 to 175 pounds per square foot. Joists

are fastened to the top during fabrication or to

supports of the sides during assembly. The top

without the joists consists of light (nominal

1-ineh) frame members and sheathing similar to

the side. Spacing of the top struts is usually

the same as in the sides.

Because crates are exposed to variable weather

con'ditions, the tops are ordinarily designed to be

waterproof. Lumber-sheathed crates may be waUPPER

FRAME.

MEMBER

*-24"

STRUTTT

-24"

41

TOP PANEL THICKNESS

VLESS SHEATHING

LOWER

FRAME

MEMBER

5 !

V. <o ' ^ ^

^\J :r

? i

o Î

Lb

^24

THICKNESS OF

SIDE PANET

SHEA THING

"^^

HORIZONTAL

ABRACE-

' ÍBY 4"OR

2'BY 4"

^ ^

o ^

^ >

? I

Ci t

K

PLYWOOD

JOINT

METAL STRAP

'(BOLTED CRATE)

^

^

^

:^^'>c^^^

Ch

4-

k.

5

<4^

Cï^

CíUi

:í^

O

'

THICKNESS OF END HEADER

(ADD THICKNESS OF PLYWOOD

FLOORING WHEN USED)

M-1196Ö5

Figure 27.—End panels for plywood-sheathed crates of three

heights.

terproofed with a heavy asphalt-impregnated

paper placed over the top and top edges after

assembly, but often this paper is damaged during

shipment. A better top is the double-sheathed

top, described below. In a plywood-sheathed

crate, where the plywood is fastened to each member, water resistance can be pro\dded by a bead

of calking compound made along each plywood

joint after naihng. A 4-inch-wide strip of waterproof paper under each joint also prevents water

entry.

To minimize water entry, top sheatliing extends

beyond the side and end sheathmg. Placement

of members and nailing should follow figure 28

and the methods described for the sides and ends.

When joists must be fastened to the top by nailmg through the plywood and the 1-inch frame

members into the 2-inch edges, use tenpenny or

twelvepenny nails spaced about 10 inches apart.
42 AGRICULTURE HANDBOOK 25 2, U.S. DEPT. OF AGRICULTURE

THICKNESS OF

SIDE SHEATHING

-THICKNESS OF

END SHEATHING

ROOFING FELT

I" SHEATHING

BOARDS

LENGTHWISE SHEATHING

HEADER

SIDE FRAME

MEMBER

THICKNESS OF

V- SIDE SHEATHING

\^THICKNESS OF

END SHEATHING I SHEATHING BOARDS

ROOFING FELT

CROSS SHEATHING

1/4" PLYWOOD

SIDE FRAME MEMBER

Figure 29.—Typical top for sheathed crates through 54 inches

wide: A, Inside view,- B, fabrication.

Figure 28.—Typical top for sheathed crate: A, Inside view; ß'

fabrication.

Dov.hl€-sh€athed tops.—Double-sheathed tops

consist of a supporting framework of joists and

headers, a plywood covering to add rigidity, a

roofing paper for waterproofing, and a lumber

sheathing for mechanical protection (fig. 28).

Since tops are designed for loads of 50 pounds

per square foot, joist sizes increase as the width

of the top increases. Figures 29, 30, and 31 show

the details for tops of various widths. Crates

with tops up to 54 inches wide require no joists.

Those over 54 through 60 inches wide use end

joists that are 2 by 4 inches, laid flat. Other

joists are 2 by 6 inches spaced 24 inches on center.

For crates over 60 tlirough 120 inches wide,

joists are placed on edge, spaced 24 inches on

center, and vary by span:

ßv^n Joist size

[inches) (inches)

60 to 66 2 by 4

66 to 78 2 by 4 plus 1 by 4, or a 3

^ by 4

nni^?5o Two 2 by 4's, or a 4 bv 4

90 to 102 2 by 6

102 to 120 2 by 6 plus Ibv 6, or a 3

by 6

i

1 2AI " .1 SIDE SHEAT |- 24 ' ' i. 1 «

It —1

'

^ ^ l^

X K ROOFING ^ s' ^ Î' FELT /

5^\

/

\^

1 O J ¿: t^i /

__

HFADFR

'<^J

/ n^ 1 jK

\ \l-= ^/ /

THICKNESS OF

-'^

REINFORCING PLYWOOD JOINT

^ " I JOIST

THICKNESS OF END

SHEA THING

I"SHEATHING BOARDS

1/4 PLYWOOD

B ROOFING FELT

JOIST (FLAT)

HEADER

LENGTHWISE SHEATHING

M-119697

F¡9ure 30.—Typical top for sheathed crates over 54 throush 60

inches wide: A, inside view; B, fabrication.
WOOD CRATE DESIGN MANUAL 43

THICKNESS OF

SIDE SHEATHING

l^END . I JOIST i

^ JOISTS^

'n '//

PLYWOOD

JOINT^

I I

^ \

i^

:ii

^ THICKNESS OF END

SHEA THING

REINFORCING

JOIST

I SHEATHING BOARDS

LENGTHWISE SHEATHING

1/4 PLYWOOD

JOIST

Figure 31.—Typical top for sheathed crates over 60 through 1 20

inches wide: A, Inside view,- B, fabrication.

When no joists are used in the top or when a

joist does not coincide with the center of bahmce,

a grabhook reinforcing* joist should be located at

the center of balance. The size should be selected

as follows:

Size of single Gross loads Length of

nnforcing not joist not

joist exceeding exceeding

(inches) (pounds) (inches)

2 by 4 1,000 72

2 by 4 2,000 60

2 by 4 3,000 48

2 by 4 5,000 36

4 by 4 10, 000 96

4 by 4 15, 000 72

4 by 4 22, 000 60

When the gross load exceeds 22,000 pounds, or

the width, exceeds 96 inches for any loads over

10,000 pounds, two 4- by 4-inch joists should be

placed 2 to 3 feet on each side of the center of

balance, for handhng with two sets of grabhooks.

Plywood-sheathed tops.—Tops may also be constructed entirely of plywood on 1- by 4-inch frame

members. Frame members are spaced 24 inches

on center. The tops are fabricated with clinched

nails, as are the side and end panels of plywoodsheathed crates. Use ^^inch pljnvood for loads

not exceeding 10,000 pounds and }^inch plywood

for loads over 10,000 pounds. The joist system,

consisting of joists and headers, should conform

to those in figures 29, 30, and 31, except that tops

without joists should be hmited to 14 inches in

width. Tops over 14 through 60 inches wide

should have 2- by 4-inch joists.

Assembly

Crates are most commonly assembled by nails

(nondemountal)le) or by lag screws (demountable).

A combination assembly includes nailing the sides,

ends, and top together to form a cap, which is

fastened to the base with lag screws. Most

articles shipped in crates are anchored to the

base. This method permits removing the base

lag screws and lifting the cap for easy removal of

the item, rather than disassembling the crate.

There is little or no basic difference in the

assembly of a lumber- and a plywood-sheathed

crate. Both require that the receiving members

for lag screws be at least 2 inches thick. Lag

screws and nails are usually about one-half inch

longer for lumber-sheathed crates than for plywood-sheathed crates and their spacing may vary

between the two types of crates.

Fastening sides to base,—In nailing the sides of

the crate to the skids or sills, the number of nails

required is based on the gross weight of the crate

and contents. Table 14 lists the number of nails

required for each 1,000 pounds of load. Half of

the nails required should be spaced evenly along

each side (fig. 32), no more than 3 inches apart.

A skid 2 inches deep requires one row of nails; a

skid or sill 4 inches deep, two rows; and a skid or

sill over 4 inches deep, three rows.

The lag screws required for fastening sides to

the base in skid-type crates are listed in table 15.

The screw sizes are usually based on the thickness

or depth of the skids. For 2-inch skids, use lag

screws Yie inch in diameter; 3- or 4-inch skids,

%- or K-inch; and for 6-inch or larger sldds, ^^inch

or larger. Half of the required number should be

spaced evenly along each side of the base. Maximum spacings are:

Lag screw size Spacing

(inches) (inches)

KebyS 12

%by3 16

^2 by 4 20

rsby 4 20

The minimum length is usually based on diameter. The minimum distance each lag screw

should penetrate into the receiving member is:

Lag screw diameter Penetration

(inch) (inches)

Mo 2

% 2

5/o 3

%:::::::: 3H

The recommended minimum length of lag

screws equals the thickness of the side plus the

penetration distance. However, lag screws may

be as long as the total thickness of the members
44 AGRICULTURE HANDBOOK 2 5 2, U.S. DEPT. OF AGRICULTURE

TOP TO SIDE

SIDE TO TOP

END TO ^/I5^^"^X4

END TO SIDE

LUMBER OR

PL YWOOD

SHEATHING

SIDE TO BASE

(USE LAG SCREWS

FOR HEAVY CRATES)

Figure 32.—Nail assembly of sheathed crate: A, Lumber- or

plywood-sheathed crate,- B, corner detail.

being fastened. The number required is found

by rule 5, p. 20.

Plywood- and lumber-sheathed sides for heavy

crates require a 1-inch fastening member or a lag

screw steel reinforcing strap nailed along the

fastening area to reinforce the sheathing.

Fastening ends to base.—The end panels should

be fastened to the end headers of skid bases or to

the end sills with nails spaced no more than 3

inches apart (fig. 32). The nails should be placed

TABLE 15.—Minimum number ^ of lag screws

required to assemble sides to base of sheathed

crates using lag screw reinforcing strap (skids of

group II, III, or IV woods)

Weight

of crate

and contents

(pounds)

Hß- by 3-

inch lag

screws (for

flat skids 2

by 4 inches)

%- by 3-

inch lag

screws (for

skids 3 by 3

or 3 by 4

inches)

H- by 4-

inch lag

screws (for

skids 4 by 4

inches)

%- by 4-

inch lag

screws (for

skids 4 by 6

inches or

heavier)

2,000

3,000

4,000

6,000

8, 000--

12

16

20

32

6

10

14

20

24

6

6

8

12

16

18

22

26

30

32

36

6

6

6

8

10

10 000 12

12 000 14

14' 000 16

le' 000 18

is' 000 22

20 000 24

24 000 28

28 000 32

32 000 36

36 000 42

40, 000 46

1 Use one-half the total on each side.

is 3 per side and 2 per end.

Minimum number

in two or more rows when the depth of the end

member is over 2 inches. Nail types and details

are outlined under the nailing rules, p. 17.

Demountable skid-type bases may be assembled

with lag screws or similar fasteners. Military

t3^pe crates require reinforced sheathing as described above in sides-to-base fastenings. Lag

screw lengths and sizes are the same as used in

fastening sides to base. Spacing should follow

the pattern shown in figure 33.

Fastening ends and sides together.—The members

are usually arranged so that the sheathing of the

side can be nailed to the edge strut of the end.

The end can then be fastened to the side by

nailins; through the sheathing and edge strut into

the edge strut of the side (fig. 32). This double

TABLE 14.—Minimum number ^ of nails, per thousand pounds of gross load, required to fasten sides to base

of a sheathed crate

Sinker or cooler nails Corker nails Common nails

Skids of

wood group Sevenpenny

Eightpenny

and

ninepenny

Tenpenny

Sevenpenny

Eightpenny

and

ninepenny

Tenpenny

Sevenpenny

Eightpenny

and

ninepenny

Tenpenny

II 23

26

19

19

21

16

18

19

14

24

26

19

17

19

14

15

16

12

19

21

16

15

17

13

13

III__. 14

IV___ 10

For each side use one-half of total required.
WOOD CRATE DESIGN MANUAL 45

NOT LESS THAN

2 LAG SCREWS

NOT LESS THAN 3 LAG SCREWS

NOT LESS THAN

2 LAG SCREWS

LAG TO ENDS OF JOISTS OR

INTO EDGE MEMBER OF TOP

LUMBER OR

PLYWOOD SHEATHING

SKID MAXIMUM LAG SCREW SPACING

5/16" - 12"

3/8" - 16"

1/2" AND 5/8" -20"

M-119680

Fi3urc 33.—Las screw assembly of military fype sheathed crates.

nailing results in a strong corner because at least

one set of nails is always in lateral resistance.

The size and spacing of nails should follow figure

32 and the general nailing rules.

In demountable crates, the lag screws are

located in the end panels. They pass through the

sheathing and edge struts of the ends and penetrate the center of the edge struts of the sides.

Lag screws used in the edge of 2-inch members

should be Ke inch in diameter. In struts thicker

than 2 inches use %-inch lag screws. Spacing is

shown in figure 33. Lead holes and other details

should follow the general rules for lag screws, p. 20.

Fastening top to sides and ends.—Because of the

variations in top designs, many different fastening

methods are necessary. However, the principles

of fastening the top \o the side and end panels

are generally the same. Two methods are commonly used: (1) nailing through the sheathing of

one panel into the edge of a frame member of the

other panel, and (2) nailing or driving lag screws

through the sheathing and frame member of one

panel into the frame member of the other. If

this double or cross fastening can be used to fasten

the top to sides and ends, as in nailing the side

and end panels together, it will result in a joint

that is resistant to high withdrawal stresses.

Tops made of light framework and sheathing

fastened to a series of top joists are usuallv nailed

to the side and end panels (fig. 32). Twelvepenny nails are spaced 4 to 5 inches apart and

staggered when the top is lumber sheathed. Tenpenny nails are used in plywood sheathing. These

nails pass through both the sheathing and the

1-mch frame of the top and into the 2-inch upper

member of the side or end.

Some tops may be constructed so that the sides

and ends must be fastened with nails through

their sheathing into the edge members of the top.

The sides are also nailed through their sheathing

into the ends of each joist.

The design of most demountable crates requires

that the lag screws be placed in the side and end

panels. Lag screws are not placed in the top panel

because their heads would snag other crates or

boxes piled on top. As shown in figure 33, the

lag screws should be spaced about 20 to 24 inches

apart and so placed that they penetrate the sheathing and upper frame members of sides or ends and

enter the fastening members of the top. A lag

screw YiQ inch in diameter may be used in the edge

of a 2-inch fastening member, a %-inch lag screw

in larger fastening members. The length of these

lag screws should be based either on the sum of all

members or on the minimum penetration plus

the side or end thickness.

LIMITED-MILITARY SHEATHED CRATES

Plywood-sheathed crates of the limited-military

type are intended for use in the domestic or export

shipment of bulky items of not over 2,000 pounds.

They are designed to be economical and to resist

moderate stacking loads, average handling conditions, and light top loads (the weight of a man

at or near the center of the span for about each

3 feet of crate length).

Limits of outside dimensions are 20 feet long,

12 feet wide, and 12 feet high. The crates are

semidemountable: the top, sides, and ends are

nailed together and this unit is fastened to the

base with lag screws.

Base

The base consists of cross skids and stringers

nailed together and covered with plywood when

necessary. The size of members and their location and placement are shown in figure 34. When

load-bearing floorboards are required because of

concentrated loads, the sizes should be selected

from table 11, p. 31.

Sides

Sides are made with 1-by 6-inch lower frame

members and 1-by 4-inch struts. The upper

frame members are arranged as shown in figure 35.

Plywood is three-eighths inch thick, with joints

made at the centers of struts or joint cleats.

Joints may be made at ends of plywood panels

when crates are more than 8 feet high. Ventilation is provided as shown.

Ends

Ends are similar to the sides, but do not require

joist spacers and ventilation (fig, 36). Member

sizes and arrano-ements are the same as in the sides.
46 AGRICULTURE HANDBOOK 25 2, U.S. DEPT. OF AGRICULTURE

STRINGER 20^ NAIL

(CLINCHED)

CROSS SKID

3/8 PLYWOOD

(USE 1/4" PLYWOOD

WHEN LOAD-BEARING

FLOORBOARDS ARE

USED.)

45° HALF-BEVEL

LOAD-BEARING

FLOORBOARD

WHEN REQUIRED

PLYWOOD

END JOINT

USE 2"BY4"CROSS SKIDS AND

STRINGERS EXCEPT 2"BY 3"

MEMBERS FOR LOADS TO 500 LB.,

LENGTH TO 10' AND WIDTH TO 5'.

Fisurc 34.—Base for limited-military type sheathed crate.

Top

The three kinds of tops for this type of crate

are based on the crate width (fig. 37). For widths

that do not exceed 60 inches, the top consists of

l-b}^ 4-inch cross struts spaced 24 inches on center

and 1-by 4-inch side members. For tops over 60

inches wdde and not exceeding 96 inches, 2-by

4-inch joists placed flat are used to support top

loads. Plywood, three-eighths inch in thickness,

is used full length without end joints. Tops

over 96 inches in width use 2- b}^ 4-inch joists on

enge. The narrow tops are fabricated in panel

form before assembly. Tops over 60 inches

wide are nailed together during assembly. Calking compound for waterproofing is applied at

all plywood joints just before naihng.

Assembly

The sides, ends, and the top are nailed together

as a unit, which is fastened by lag screws to the

base. The size and spacing of nails are shown in

figure 38.

Lag screws, ){^ by 3 inches, fasten the sides to

the strmgers of the skids. The ends are fastened

to the cross skids. The corners may be reinforced,

if necessary, with annealed strapping, applied as

listed on p. 22.

LIGHT-DUTY SHEATHED CRATES

Light-duty type sheathed and cleated crates are

intended for items of not over 1,000 pounds that

require moderate mechanical protection. Outside

dimensions should not exceed 12 feet in length, 5

feet in width, and 7 feet in height. Sheathing may

be paper-overlaid veneer or plywood.

Base

The base is made up of 2- by 3-inch cross skids

and longitudinal skids wâth a diagonal at each end

panel to provide stiffness (fig. 39, A), Cross

skids are spaced 24 inches on center when sheathing in the side, end, and top panels is plywood,

and 20 inches on center when it is paper-overlaid

veneer. When a covered base is required, K-inch

plywood may be used. Load-bearing floorboards

as listed in table 11 are used for concentrated

loads.

Sides, Ends, and Top

The sides, ends, and top are made as shown in

figure 39, B. When the sheathing is Ke-inch

plywood, the cleats are 1 by 4 inches, spaced 24

inches on center in line with the cross skids of the

base. With Ke-inch paper-overlaid veneer, the

1-by 4-inch cleats are spaced 20 inches on center.
WOOD CRATE DESIGN MANUAL 47

24" 24"

(MAX.) (MAX.)

|gig?o^ö-c?

SLOPED TO DRAIN OUT,

ALTERNATE PANELS,

JOIST SPACER BOTH SIDES^

NAIL TOfLYWOOD y^ \

-<^^^^o'J^

ALLOW

1—rn——

FOR JOISTSWIDT HS OVER 60"

\

/'BY4'^\

STRUTS

A \-a"

~ ^_JJí4 _o_ o _o_ o

CRATE WIDTHS TO 60" /\

USE VENT BLOCKS \\

I . ^1,

EQUAL TO

THICKNESS OF

TOP FRAMING

I"BY 6"LOWER—^

FRAME MEMBER

I"BY 4" FOR NAILING

AT PLYWOOD JOINT

B

{—J/4'

1

NO SPACER

REQUIRED

-3/4" VENT

HOLE

I"BY 4" BLOCK FOR

VENT HOLES

7" JOIST SPACERS

¿-5/8

JOIST-2"BY 4

FLAT

VENT HOLES

THROUGH 60 WIDE

OVER 60

THROUGH 96" WIDE

r

X 3-5/8"

JOIST-2"BY 4'

ON EDGE

UPPER FRAME

MEMBER

OVER 96 WIDE

Fisure 35.—Sides for limited-military type sheathed crate: A, Side view; ß, detailed construction of side panels, showing vents for

crates of various widths.

6«2-318 0—64-
48 AGRICULTURE HANDBOOK 2 5 2, U.S. DEPT. OF AGRICULTURE

EQUAL TO

THICKNESS OF

TOP FRAMING

OR JOISTS

I BY 4 STRUTS TO FIT BEVEL OF

CROSS SKIDS

I"BY 6" LOWER FRAME MEMBER

ENDS TO BE HEIGHT OF SIDES PLUS 1-5/8"

M-119701

Figure 36.—Ends ior limited-military type sheathed crate.

3/8^ *T=^

-

24"

~ MAXF*

24"

MAX.

PLYWOOD JOINTS CALKED

'DURING FABRICATION

1 1

6^

CROSS

STRU-r

l"BY4"

/

1

5 \ 1

lu 1 1 V

3/8 PLYWOOD

NO END JOINTS

3/8^

il

SIDE TO TOP

WIDTHS TO 60"-

e'^ NAILS

WIDTHS OVER 60"-

TWO 8^ NAILS

AT EACH JOIST

TOP TO SIDE

END TO TOP

6^ NAILS

' (STAGGER

FOR JOISTS)

SIDE TO BASE

5/16"BY 3" LAG

SCREWS

SIDE TO END

END TO SIDE 6^ NAILS

10^ NAILS

END TO BASE

5/16" BY 3"

LAG SCREWS

M-l 19703

Figure 38.—Assembly of limited-military type sheathed crate.

/ BY 4

NAILING CLEAT

PLYWOOD JOINTS CALKED

DURING ASSEMBLY

M-l 19702

Figure 37.—Inside view of the tops of three widths of limitedmilitary type sheathed crates: A, Narrow; B, intermediate;

and C, wide.

Assembly

The side, end, and top panels are assembled by

nailing as shown in figure 39, B, and this unit is

fastened to the base with nails or lag screws.

Lag screws are used when semidemountability is

desired. For additional strength, tension

strapping may be applied as shown.
WOOD CRATE DESIGN MANUAL 49

FORK LIFT MEMBER

FOR WIDTHS OVER 42"

BOLT

ADD LOAD-BEARING

MEMBER WHEN REQUIRED

HALFBEVEL

THICKNESS OF SHEATHING

AND FRAME MEMBER

CROSS SKID

SPACING

CLEATS,

8^ NAILS FOR

NAIL ASSEMBLY

12"-14"

FOR DEMOUNTABLE BASE

5/16" BY 3" LAG SCREWS

Figure %9.—A, Construction of base; B, assembly of light-duty type cleated panel crate.
50 AGRICULTURE HANDBOOK 2 5 2, U.S. DEPT. OF AGRICULTURE

OPEN CRATES

Open crates are most often used for packao:in<2;

items not affected by weather or to be stored

inside. Partial protection from tlie weather is

sometimes provided by a waterproof shroud over

the contents. Open crates are customarily assembled by either bolting or nailing. Military

type open crates (fig. 40) are most often used for

heavy loads.

Other types of open crates are used frequently

in military and industrial shipping by truck or

rail. These types are relatively light, since the

components are mininmm size. They resist

moderate stacking loads and provide reasonable

protection from handling hazards. Shrouds or

partial coverings sometimes protect the item from

weather. An example of the limited-military

type of open crate, for loads to 2,500 pounds, is

shown in figure 41. A typical light-duty crate

(fig. 42) is designed for loads to 200 pounds.

ASSEMBLY

STRAPPING

RUBBING

STRIPS

Figure 41.—Limited-military type open crate for loads to 2^500

pounds, designed for the shipment of light, bulky items that

do not require a waterproof container.

THREE-WAY CORNER

NAILING

LAG SCREWS OR BOLTS

M-l 19655

pounds: A. fastened primarily with lag screws or bolts, 8

M-119657

Figure 42.—Light-duty open crate (loads to 200 pounds) with

three-way corner nailing, the key to proper assembly nailing

of crates of this type.

MILITARY TYPE OPEN CRATES

Military type open crates may be used for either

domestic or overseas shipments of items that do

not exceed 10,000 pounds in weight. The maximum size is 16 feet long, 8 feet wide, and 8 feet

high.
WOOD CRATE DESIGN MANUAL 51

LOAD-BEARING

MEMBERS

FILLER STRIP

1/4 BOLT

END HEADER

5"BY 3" OR 4"BY 4"j

THICKNESS OF END SHEA THING

Figure 43.—Base for military type open crate.

r-TH/CKNESS OF FRAME MEMBERS OF TOP

_GUSSET PLATES USED ONLY WITH I"

MEMBERS.

UPPER FRAME MEMBER

STRUT.

["-PANEL LENGTH-^

I THICKNESS OF END

FRAME MEMBERS FOR

^SIDE PANELS.

THICKNESS OF SIDE

SHEATHING BOARDS

FOR END PANELS.

I I I I

LOWER FRAME MEMBER

SHEATHING BOARDS

{DEPTH OF SKID LESS 1/4" FOR SIDE PANELS.

[DEPTH OF END FLOOR BOARD FOR END PANELS.

M-J:

Figure 44.—Sides or ends for military type open crates.

Base

The base of a military type open crate is made

oí 4- by 4-inch skids spaced no more than 42 inches

apart. To prevent splitting, carriage bolts are put

through each skid, 2 to 3 inches from the ends (fig.

43). Areas for sling and forklift handling should

be left between the rubbing strips. Skids are

lastened together by end headers, floorboards, and

diagonals. The base may be reinforced for forklift

handling by 2-inch floorboards spaced threeeighths inch apart. Size of the load-bearing floorboards should be selected from table 11. Unsheathed floor areas should have single or double

1- by 6-inch diagonals.

Sides and Ends

The side and end panels of military type open

crates are constructed as shown in figure 44. The

number of panels can be determined by dividing

the crate length by the height. The nearest whole

number will be the correct number of panels, which

enables the diagonals to form as near a 45° angle

with the edge as possible. When the sides and ends

are over 5 feet high, an intermediate longitudinal

member is added at the level at which the diagonals

intersect.

For net loads of 6,000 to 10,000 pounds and

heights that do not exceed 6 feet, size of members

may be selected from table 16. When the crate is

over 6 feet high, all frame members should be 2 by

4 inches. Under all conditions, the upper frame

member and the struts should be at least 2 by 4's.

For loads of not over 4,000 pounds and heights of

less than 6 feet, all members except struts and

upper frame members are 1 by 4's.

Sheathing boards are nominal 1-inch material

and should provide sufficient area for nailing to the

base and top members (fig. 44). For naiUng to the

the base, the total number of nails should be determined from table 14; the number of sheathing

boards necessary for this nailing area can then be

determined, using the nailing patterns of figure 6.

Normally the amount of sheathing in figure 44 is

suflScient, but additional boards may be required

for heavy crates. Plywood strips one-half inch

thick may be substituted for lumber in sides, ends,

or tops and should be as wide as the total width of

the sheathing boards that would be required.

When 1-inch frame members are used, }^inch

plywood gusset plates should be nailed at the

intersection of the diagonals (fig. 44) with sevenpenny nails clinched on the sheathed side. Use 12-

by 12-inch sizes when diagonals are 1 by 4 inches,

and 18- by 18-inch sizes when diagonals are 1 by 6's.
52 AGRICULTURE HANDBOOK 2 52, U.S. DEPT. OF AGRICULTURE

TABLE 16. Panel member dze^^ for muitary-type open cmten designed for net loads of 6,000 to lOfiOO pounds

6,000 POUNDS

Length

Feet

10

12

16

Meml^ers

Upper frame member

Lower frame member

Strut

Diagonal

Upper frame member.

Lower frame member

Strut

Diagonal

LTpper frame member.

Lower frame member.

Strut

Diagonal

Upper frame member.

Low^er frame member.

Strut

Diagonal

Upper frame member.

Lower frame member.

Strut

Diagonal

4-foot width and a

height of—

2 feet

Inches

2 by 4

1 by 4

2 by 4

1 by 4

1 by 4

2 by 4

1 by 4

2 by 4

1 by 4

2 by 6

1 by 4

4 feet

Inches

2 by 4

1 by 4

2 by 4

1 by 4

1 by 4

2 by 4

1 by 4

2 by 4

1 by 4

2 by 4

1 by 4

6 feet

Inches

2 by 4

1 by 4

2 by 4

1 by 4

1 by 4

2 by 4

1 by 4

2 by 4

1 by 4

2 by 4

1 by 4

6-foot width and a

height of—

2 feet

Inches

2 by 4

1 by 4

2 by 4

1 by 4

1 by 4

2 by 4

1 by 4

2 by 4

1 by 4

2 by 6

1 by 4

4 feet

Inches

2 by 4

1 by 4

2 by 4

1 by 4

1 by 4

2 by 4

1 by 4

2 by 4

1 by 4

2 by 4

1 by 4

6 feet

Inches

2 by 4

1 by 4

2 by 4

1 by 4

1 by 4

2 by 4

1 by 4

2 by 4

1 by 4

2 by 4

1 by 4

8-foot width and a

height of—

2 feet

Inches

2 by 4

1 by 4

2 by 4

1 by 4

1 by 4

2 by 4

1 by 4

2 by 4

1 by 4

2 by 6

1 by 4

4 feet

Inches

2 by 4

1 by 4

2 by 4

1 by 4

1 by 4

2 by 4

1 by 4

2 by 4

1 by 4

2 by 4

1 by 4

8,000 POUNDS

10

12

16

10

Upper frame member

Lower frame member.

Strut

Diagonal

LTpper frame member.

Lower frame member.

Strut

Diagonal

Upper frame member.

Lower frame member.

Strut

Diagonal

Upper frame member.

Lower frame member.

Strut

Diagonal

Upper frame member.

Lower frame member

Strut

Diagonal

2 by

a by

1 by

2 by

1 by

1 by

1 by

2 by

•1 by 4

1 by

2 by

a by 4

1 by

2 by

1 by

1 by

2 by

1 by

by

by

by

by

by

by

1 by

1 by

2 by

1 by

1 by

2 by

1 by

1 by

2 by

1 by

1 by

2 by

1 by

Iby

1 by

2 by

1 by 4

1 by 6

2 by 4

1 by 4

1 by

2 by

Iby

1 by

2 by 4

1 by 4

1 by

2 by

1 by

1 by

1 by

2 by

1 by 4

1 by 4

2 by 6

1 by 4

1 bv 4

2 by 6

1 by 4

1 by 4

2 by 4

1 by 4

by

by

by

by

by

by

by

by

by

1 by 4

1 by 4

2 by 4

1 by 4

1 by 4

2 by

1 by

1 by

2 by

1 by

1 by

1 by

2 by

1 by 4

Iby

2 by

1 by 4

by

by

1 by

1 by

2 by

1 by

1 by

2 by

1 by

1 by

Iby

2 by

1 by

1 by

2 by

1 by

1 by

2 by

1 by

1 by

2 by

Iby

Iby

2 by

1 by

Iby

1 by

2 by

1 by 4

1 by

2 by

1 by

1 by

2 by

1 by

1 by

10,000 POUNDS

Upper frame member.

Lower frame member

Strut

Diagonal

Upper frame member

Lower frame member

Strut

Diagonal

Upper frame member.

Lower frame member.

Strut

Diagonal

2 by 4 2 by 4 2 by 4 2 by 4 2 by 4 2 by 4 2 by 4 2 by 4

1 by 4 1 by 4 1 by 4 1 by 4 1 by 4 1 by 4 Iby 4 2 by 4

1 by 4 1 by 4 1 by 4 1 by 4 1 by 6 1 by 4 Iby 6 2 by 4

1 by 4 Iby 6 1 by 4 1 by 4 1 by 6 1 by 6 1 by 4 2 by 4

2 by 4 2 by 4 2 by 4 2 by 4 2 by 4 2 by 4 2 by 4 2 by 4

1 by 4 2 by 4 1 by 4 1 by 4 2 by 4 1 by 4 1 by 4 2 by 4

1 by 4 2 by 4 1 by 4 Iby 4 2 by 4 1 by 4 1 by 6 2 by 4

1 by 6 2 by 4 1 bv 6 Iby 6 2 by 4 1 by 6 1 by 6 2 by 4

2 by 4 2 by 4 2 by 4 2 by 4 2 by 4 2 by 4 2 by 4 2 by 4

1 by 4 1 by 4 1 by 4 1 by 4 1 by 4 1 by 4 iby 4 iby 4

1 by 4 1 by 6 1 by 4 Iby 4 1 by 6 Iby 4 Iby 4 Iby 6

1 by 6 Iby 6 Iby 6 Iby 6 1 by 6 1 by 6 Iby 6 Iby 6
WOOD CRATE DESIGN MANUAL 53

TABLE 16.—Panel member sizes for military-type open crates designed for vet loads of 6,000 to 10,000

pounds—^Continued

10,000 POUNDS—Continued

Length

Feet

12

16

Members

Upper frame member.

Lower frame member.

Strut

Diagonal

Upper frame member.

Lower frame member.

Strut

Diagonal

4-foot width and a

height of—

2 feet

Inches

2 by 6

1 by 4

1 by 4

by 4

by 8

by 4

by 4

by 6

4 feet 6 feet

Inches

2 bv 4

1 bv

1 by

1 bv

2 by

1 bv

1 bv

1 bv

Inches

by

by

by

bv

bv

by

bv

by

6-foot width and a

height of—

2 feet

Inches

by 6

4 feet

Inches

2 by

1 by

1 by

1 by

2 by

1 by

1 by

1 by

6 feet

Inches

2 by

2 by

2 by

2 by

2 bv

2 by

2 by

2 by

8-foot width and a

height of—

2 feet

Inches

2 by 6

1 by 4

1 bv 4

1 by 6

2 by 8

1 by 4

1 by 4

1 by 6

4 feet

Inches

by 4

by 4

by 4

by 6

by 6

by 4

by 6

by 6

6 feet

Inches

2 by 4

by 4

by 4

by 4

by 4

by 4

by 4

by 4

Tops

The tops of military type open crates of various

widths are constructed as shown in figure 45.

Frame members are nominal 1 b}^ 6's or, if the tops

are not more than 24 inches wide, 1 bv 4's. Plywood gussets should be added to the intersection

of all cross diagonals. Sheathing is applied as

described for the sides and ends.

^ssem biy

Military type open crates are assembled as

shown in figure 46 and as described in the section

on sheathed crate assembly. Strapping may be

used for reinforcing, applied as listed on p. 22.

LIMITED-MILITARY TYPE OPEN CRATES

Limited-military t\T)e open crates, also for

domestic or overseas shipment, are of three styles,

sizes, and load capacities. They are not designed

for large superimposed top loads, so heavy joist

systems are not included. However, the sides

and ends are capable of withstanding moderate

top loads such as might be imposed by normal

Hke-on-like stacking.

Styles A and A-1 Open Crates

A stjde A open crate (fig. 47) has a load limit of

1,000 pounds, with maximum dimensions of 6 feet

in length and 4 feet in width and height. The base

is made up of 2- by 4-inch skids and end headers

for loads of not over 500 pounds and 2 by 6's for

loads of not over 1,000 pounds. Rubbing strips

are 2 by 4's. Dimensions of load-bearing floorboards can be selected from table 11. All members

of the sides, ends, and top, as well as the diagonal

of the base, are 1 by 6's.

A'similar style, À-1, uses all 1- bv 4-inch members for side, end, and top panels (fig. 48). The

weight limitation is 250 pounds. Maximum

dimensions are 4 feet in length and 3 feet in width

and height. Skids and end headers are also 2 by

4's. Both styles A and A-1 emplo}^ eightpenny

sinker nails spaced 6 to 8 inches apart for side-toend and end-to-top assembty. The sides are nailed

to the base as in figure 6; ends are not fastened

directly to the base. The crate ma}^ be strengthened by metal strips (fig. 48).

Style B Open Crates

vStyle B (fig. 49) is similar to style A except that

the maximum load is 2,500 pounds, and the maximum dimensions are 12 feet in length and 6 feet in

width and height.

The base is made up of 4- by 4-inch skids; three

skids are used when the distance between outside

skids is more than 36 inches. Rubbing strips are

2 by 4's. End headers are 2 by 6's for crates that

do not exceed 4 feet in width and 4 by 4's for

widths over 4 feet. Dimensions of load-bearing

floorboards can be selected from table 11.

The sides are made of 1 by 6's. A crat^e over

48 inches high needs an intermediate horizontal

member. Space struts not over 40 inches apart,

so that the angle formed by the diagonal is as near

45° as possible.

The struts of the end are 2 by 4's. An intermediate strut is added when the crate is over 42

inches wide. Other members are 1 by 6's, except

that a 1- by 8-inch lower edge member is needed

when the end cross members of the base are 4 by

4's.

All members of the top are 2 by 4's. A top

over 42 inches wide needs an intermediate longitudinal member, alined with the center strut of

the end. The joists are placed flat and alined with

the struts of the side panel. Each end panel of

the top has a diagonal (fig. 49).

Style B crates may be assembled either with

eightpenny sinker nails in the same manner as
54 AGRICULTURE HANDBOOK 2 5 2, U.S. DEPT. OF AGRICULTURE

THICKNESS OF i

SIDE SHEATHING-X LONGITUDINAL MEMBER

THICKNESS OF END '

SHEATHING BOARDS

THICKNESS

OF SIDE

SHEATHING

BOARDS

DIAGONAL

LENGTH

STRUT

SHEATHING

BOARDS

LONGITUDINAL MEMBER

DIAGONAL

THICKNESS OF END*

SHEATHING BOARDS

STRUT

PL YWOOD

GUSSET

GRANEL LENGTH1

LONGITUDINAL MEMBER

PL YWOOD

GUSSET

INTERMEDIATE

-^^ MEMBER

DIAGONAL

-STRUT

PANEL LENGTH^ SHEATHING BOARDS

M-l 19707

Figure 45.—Narrow, intermediate, and wide tops for military type open crates.
WOOD CRATE DESIGN MANUAL

CORNER REINFORCING STRAP

55

12^ NAIL

LOCATE AT

HORIZONTAL

REINFORCING'

BRACE

20^ NAILS

(PREDRILL)

8^NAILS

8^ NAILS

style A and A-1 crates or with lag screws. The

crate is strengthened by steel straps (fig. 49). The

diagonals are arranged to provide the maximum

number of fastening points to the base near the

center of the skid depth.

If lag screws are emploj^ed for side-to-basc

fastening they should be % inch. The minimum

number of lag screws for each side is shown in the

following tabulation, but at least one must be

placed in each strut and diagonal.

Figure 46.—Assembly of military type open crate.

Minimum

lag

screws

(xro^s, load—crate and

for

each

contents side

(pounds) {number)

1,000 ._ ._ __ 4

2,000 5

3,000 . 8

4,000 10

If lag screws are used for end-to-base, side-toend, and end-to-top assembly, they should be

/Í6- by 3-inch spaced 12 to 14 inches apart. Each

strut and diagonal of the side panel is joined by a

lag screw of the same size to the edge longitudinal

member of the top.

Style C Open Crates

A style C open crate of the limited-military

type often is used for shipping such high-density

items as sheet metal and sheets of building board.

Crates of this type should not exceed 12 feet in

length, 4 feet in width, and 2 feet in height.

When no blocking or bracing is required the

maximum gross load is 1,000 pounds. When the

item requires bracing or cushioning the maximum load is 500 pounds. Crates may be made

entirely of lumber, or of cleated plywood sides

and ends with lumber cross members in tops and

bottoms (fig. 50).

The sizes of plywood or lumber for the ends and

sides are listed in table 17.

When sides are made of two or more pieces of

lumber, inside battens of the same size as the

cleats should be alined with top and bottom cross

members and spaced no more than 3G inches

apart (fig. 50).

The top and bottom cross members and diagonals are 1 by 4's for crates 30 inches wide or less

and 1 by 6's for crates wider than 30 inches.

The sides are nailed to the ends with sinker

nails. Nail sizes and spacings for different
56 AGRICULTURE HANDBOOK 252, U.S. DEPT. OF AGRICULTURE

LOAD-BEARING END FLOOR

MEMBER

UPPER EDGE MEMBER

DIAGONAL

LOWER EDGE MEMBER^ STRUT

BASE

SKID

^RUBBING STRIP END

r-UPPER EDGE

STRUT y DIAGONAL \ MEMBER ^LONGITUDINAL MEMBER

LATERAL

MEMBERA

DIAGONAL

SIDE LOWER EDGE

MEMBER

TOP

ASSEMBLED

Figure 47.—Style A limited-military type open crate.
WOOD CRATE DESIGN MANUAL 57

END FLOOR MEMBER UPPER EDGE MEMBER

m

SKID

DIAGONAL

LOWER EDGE MEMBER

BASE RUBBING STRIP END

UPPER EDGE MEMBER LONGITUDINAL MEMBER^

DIAGONAL

«^

LOWER FRAME MEMBER

SIDE

LATERAL

MEMBER

vjLfjr

TOP

ASSEMBLED

M-119710

Fisure 48.—Sfyle A-1 limited-military type open crate.
58 AGRICULTURE HANDBOOK 2 5 2, U.S. DEPT. OF AGRICULTURE

END CROSS MEMBER UPPER EDGE MEMBER

rP

DIAGONALö STRUTDIAGONAL '^'-^^^ MEMBER ¿Q^^f^ EDQE MEMBER\

,.ca '^. . .''^ im,.iÉ^ SKID ^uii mj g

BASE ^RUBBING STRIP END

UPPER FRAME MEMBER

DIAGONAL

INTERMEDIATE MEMBER

SIDE

-LOl^'ER FRAME MEMBER

WIDTHS THROUGH 42'

cs

(£: ) dJ

K

JOISTS DIAGONAL

W

'% m} c

1 (U

^ ¿ ^/\/g/ TUDINAL MEMBER

WIDTHS OVER 42"

TOP

ASSEMBLED

Figure 49.—Style B limited-military type open crate.

M-119711
WOOD CRATE DESIGN MANUAL 59

TOP CROSS

MEMBER

BATTEN

DIAGONAL

^END CLEAT

TOP CROSS MEMBER -

DIAGONALPLYWOOD

Figure 50.—Style C limited-military type open crates of lumber

and plywood-and-lumber construction.

thicknesses of either lumber or cleated plywood

sides are given in table 18.

The top and bottom members are nailed to

the sides with eightpenny sinker nails. Tension

strapping is used to reinforce top and bottom

members (fig. 50) when shipping conditions are

moderate to severe.

TABLE 17.—Size of material jor the ends and sides

oj a Style C open crate of the limited-military

type

Maximum

net load

Thickness of ends

and sides Size of end

cleats

Size of side

cleats

Plywood Lumber

Pounds

100

250

500

1,000

Inch

%

%

Inches

%

%

Inches

'A by 2%

% by 3%

IMe by 3%

1% by 3%

Inches

% by 2%

% by 2%

% by 3%

% by 3%

LIGHT-DUTY OPEN CRATES

Crates of this type are designed principally to

protect items from normal shipping and storage

hazards, including accidental drops, with minimum

material and tare weight. They are intended for

domestic or low-hazard shipment of items that

do not exceed 4,000 pounds. They should be a

maximum of 32 feet long, 6 feet wide, and 10

feet high. They may be fastened entirely by

naus or made partially demountable by nailing

together the sides, ends, and top and then fastening to the base with lag screws. The tops are

designed not to carry superimposed loads. The

sides and ends can resist the moderate stresses

of like-on-like stacking.

TABLE 18.—Spacing of sinker nails in lumber or

plywood sides oj a style C open crate oj the limitedmilitary type

Cleated plywood sides Lumber sides

Nail size

Plywood

thickness

Nail

spacing

Thickness Nail

spacing

Penny

8

10

12

Inch

%

¥2

Inches

3

Inches

%

1M6

1%6

Inches

2H

2%

3

Auxiliary coverings of Ke-inch plywood or paperoverlaid veneer may be used on crates for items

that require the protection of some sheathing.

Filler pieces are added to the frame to provide

nailing surfaces at the edges of panels.

Base

Skids are single-piece 2 by 4's, placed flat, for

loads of not over 2,000 pounds and bases no longer

than 20 feet. For loads that do not exceed 3,000

pounds and lengths no more than 20 feet, skids

should be single-piece 3 by 3's. With heavier

loads or longer bases, the skids should be 4 by 4's,

or two 2 by 4's laminated and placed on edge.

Crates over 42 inches wide need three skids (fig.

51). Kubbing strips are fastened under each skid,

with spaces left for forklift or sling handling.

End headers are the same size as the skids (fig.

51). Load-bearing floorboard sizes are selected

from table 11. Other cross members and diagonals should be 1 by 4's for loads that do not exceed

500 pounds and crate widths of not over 36 inches,

1 by 6's for wider crates or heavier loads.

Sides

The hght-duty open crate has one of three

styles of sides, depending on the net load and

crate height.

For loads of not over 2,000 pounds and crate

heights of no more than 6 feet, sides of the style

in figure 52 should be used. The sizes of members

and the spacing of struts for crates of various

dimensions are listed in table 19.
60 AGRICULTURE HANDBOOK 2 5 2, U.S. DEPT. OF AGRICULTURE

CARRIAGE BOLT

(PLACE TO CLEAR

EDGE STRUT OF END)

HEADER

LOAD-BEARING

FLOORBOARD

DIAGONAL

ADD EXTRA SKID

CENTER OF

BALANCE

RUBBING STRIP

Figure 51." -Bases for light-duty open crates: A, Through 42

inches wide; B, over 42 inches wide.

The double-panel side design (fig. 53) is for

loads that do not exceed 4,000 pounds and heights

no greater than 8 feet. Member sizes and strut

spacing are listed in table 20.

The triple-panel side design (fig. 54) is for loads

of no more than 4,000 pounds and heights between 8 and 10 feet. Member sizes and strut

spacing are listed in table 21.

Ends

The arrangement of members in the ends

(figs. 55, 56) is determined by the height and width

of the crate and by the strut spacing. The

strut spacing should be no greater than for the

side struts. The upper frame members, intermediate horizontal members, struts, and diagonals

are 1 by 4's for loads through 500 pounds and 1

by 6's for loads over 500 pounds, except that

struts should be 2 by 4's in crates over 5 feet

high. The lower frame member is a 1 by 6

with 2- by 4-inch single end headers placed flat,

and a 1 by 8 with larger headers.

Tops

The design and arrangement of members of

the top are usually based on the width of the crate.

The styles of tops for widths through 72 inches

are shown in figure 57. Edge longitudinal

members are 1 by 4's for loads not exceeding

500 pounds and widths through 48 inches, and

1 by 6's for all other conditions. Center longitidunal members for wide crates are 1 by 4 inches.

Cross struts and diagonals should be 1 by 4's

for loads not exceeding 1,000 pounds and widths

through 48 inches, and 1 by 6's for heavier loads

and wider crates.

vssem biy

The method of assembly for the light-duty open

crate is shown in figure 58. Assembly of the covered style is shown in figure 59.

TABLE 19.—Sirut sjMcing and frame member sizes ^ for sides of single-panel light-duty open crates

Crate size limits Member sizes of sides

Length Width Height Net load

Maximum

strut

spacing

(on center)

Upper

longitudinal

Lower

longitudinal

Intermediate 2

longitudinal

Strut Diagonal

Feet

12

Inches

48

60

60

60

60

Inches

48

60

72

72

72

Pounds

300

500

1,000

1, 500

2,000

Inches

42

48

42

42

36

Inches

1 by 4

1 by 6

Iby 6

Iby 6

1 by 8

Inches

1 by 3

1 by 4

1 by 6

1 by 6

Iby 6

Inches Inches

1 by 33

Iby 4

1 by 43

Iby 6

1 by 6

Inches

Iby 4

Iby 4

Iby 6

Iby 6

Iby 6

32 "î'byï""

Iby 4

1 by 4

Iby 6

24

20

16

1 Longitudinal members shall be single pieces for lengths that do not exceed 16 feet, with approved splices permitted in lengths greater than 16 feet. » ï^ï^ t' ^

2 For crates over 48 inches high.

3 For edge struts, use 1 by 4's. But if edge struts of ends are 2 by 4's, use 1 by 6's for edge struts of sides.
WOOD CRATE DESIGN MANUAL 61

ADD INTERMEDIATE

MEMBER FOR

HEIGHTS OVER 48"

STRUT

SPACING

UPPER

LONGITUDINAL

MEMBER

A LOWER

LONGITUDINAL

MEMBER

DIAGONAL

SKID DEPTH PLUS 1-1/2'

(TRIM FOR FORKLIFT)

THICKNESS OF

EDGE STRUTS;

OF END

TO OVERLAP

END

FLUSH

\ i

DIAGONAL PLACEMENT

PROVIDES 3 FASTENING

POINTS AT MIDSPAN

FIT FILLER BETWEEN

STRUTS AND DIAGONALS

TOP AND BOTTOM

LOCATE ABOVE

FASTENING POINTS

Figure 52.—Sides for light-duty open crates, ior loads through 2,000 pounds and heights through 6 ieet: /, Side view; 6, side of short

crate; C, covered side.
62 AGRICULTURE HANDBOOK 25 2, U.S. DEPT. OF AGRICULTURE

UPPER

LONGITUDINAL

MEMBER

STRUT

SPACING

THICKNESS OF

EDGE STRUTS

OF END,

LOWER—^

LONGITUDINAL

MEMBER

INTERMEDIATE

LONGITUDINAL

MEMBER

L

-TO OVERLAP END

SKID DEPTH PLUS

1-1/2" (TRIM FOR

FORKLIFT)

FIT FILLER BETWEEN

^STRUTS AND DIAGONALS

TOP AND BOTTOM

NAIL COVERING TO

STRUTS AND FILLERS

^LOCATE COVERING ABOVE

FASTENING POINTS

M-119715

Figure 53.—Double-panel sides For lisht-duty open crates, for loads through 4,000 pounds and heights through 8 feet: Â, Side view;

ß, covered side.
WOOD CRATE DESIGN MANUAL 63

UPPER

LONGITUDINAL

MEMBER-^

STRUT

SPACING

INTERMEDIA TE

LONGITUDINAL

MEMBER

LOWER

LONGITUDINAL

MEMBER

DEPTH OF SKIDPLUS 1-1/2"

(TRIM ATFORKLIFT

AREAS)

THICKNESS OF EDGE

STRUT OF END

B

OVERLAP END FILLER

NAIL COVERING TO

3 S TRU TS A ND FIL L ERS

LOCATE COVERING ABOVE

FASTENING POINTS

Fisure 54.—Triple-panel sides for light-duty open crates, for loads tf)rough 4,000 pounds and heights between 8 and 10 feet: A,

Side view; 6, covered side.

692-318 0—64-
64 AGRICULTURE HANDBOOK 2 5 2, U.S. DEPT. OF AGRICULTURE

SAME MAXIMUM

SPACING AS I

-3/4

A

UPPER

FRAME

MEMBER

DEPTH OF

END HEADER

INTERMEDIATE

STRUT

THICKNESS OF

-SIDE SHEATHING

^3/4"

\ I V^

i-^FILLER

-FLUSH

B

COVERING

ADD FOR

HEIGHTS

OVER 48

LOWER FRAME MEMBER

Figure 55.—Ends for light-dufy open crates, for loads through 2,000 pounds and heights through 8 feet: A, Two-panel horizontal/

6, single-panel (covered); C, four-panel; and D, two-panel vertical.
WOOD CRATE DESIGN MANUAL 65

UPPER FRAME

MEMBER

SAME MAXIMUM

SPACING AS

SIDE STRUTS

HORIZONTAL

MEMBER

LOWER FRAME

MEMBER

DEPTH OF END HEADER

THICKNESS OF

-SIDE SHEA THING

173/4"

JOINT

-3/4-

-FILLER

BEi

EDGE_

STRUT

INTERMEDIATE

STRUT

Figure 56.—Ends for lisht-duty open crates, for loads through 4,000 pounds and heights through 10 feet: A, Wide and narrow doublepanel ends,- and B, wide and narrow triple-panel ends.
66 AGRICULTURE HANDBOOK 2 5 2, U.S. DEPT. OF AGRICULTURE

SAME SPACING

AS SIDE STRUTS

TOP REINFORCING

—JOIST

TO OVERLAP SIDE

AND END SHEATHING,

EDGE _ STRUT

3/4"^ COVERING

DIAGONAL

EDGE MEMBER

B

L- -- -J

/^ \

5

/-<> ^>^ c^

z^::^ ^<^ Qö ^

^.^ ^-^^^ ^^ :i; ,' ^. \,^^ 0- ^Û

^

-^ 1

"-^^ f^

1

EDGE LONGITUDINAL

MEMBER

DIAGONAL

CROSS

STRUT

CENTER

LONGITUDINAL

MEMBER

M-119909

Figure 57.—Tops for lighNduty open crates: A, Narrow top; ß, medium-width top; C, wide top.
WOOD CRATE DESIGN MANUAL 67

TOP TO END

TOP TO SIDE TOP TO END

SIDE TO TOP TOP FILLER

END TO TOP TOP TO SIDE

END TO BASE

(USE LAG SCREWS FOR

DEMOUNTABLE BASE)

END TO SIDE

SIDE TO BASE

(USE LAG SCREWS FOR

DEMOUNTABLE BASE)

SIDE TO END

TRIM STRUTS FOR SLING

AND FORKLIFT HANDLING

SIDE TO END

END TO BASE

(NAILS OR LAG SCREWS'

END TO SIDE

SIDE TO TOP

w^?/^?^ TO BASE

(NAILS OR LAG SCREWS)

SIDE TO END

TRIM STRUTS FOR SLING

AND FORKLIFT HANDLING

M-l 19702

Figure 59.—Assembly of covered style light-duty open crate

Figure 58.—Assembly of light-duty open crate.

TABLE 20.—Sirui spacing and frame member sizes ^ for sides of double-panel light-duty open crates

Crate size limits

Length Width Height Net load

Maximum

strut

spacing

(on center)

Member sizes of sides

Upper

longitudinal

Lower

longitudinal

Intermediate

longitudinal

Strut Diagonal

32_

28,

24.

20_

I6_

Feet Inches

72

72

72

72

72

Inches

96

96

96

96

96

Pounds

500

1,000

2,000

3,000

4,000

Inches

54

54

48

48

42

Inches

by 4

by 6

by 6

by 8

by 8

Inches

1 by 4

1 by 4

1 by 6

1 by 6

1 by 8

Inches

by 6

by 6

by 6

by 6

by 8

Inches

1 by 42

1 by 42

1 by 6

Iby 6

1 by 6 3

Inches

1 by 4

1 by 4

1 by 6

1 by 6

1 by 6

^ Longitudinal members shall be in single pieces for lengths

that do not exceed 16 feet, with approved splices permitted

in lengths greater than 16 feet.

2 Edge struts 1 by 6 inch minimum.

3 Edge struts 1 by 8 inch minimum.

TABLE 21.—Strut spacing and frame member sizes ^ for sides of triple-panel light-duty open crates

Crate size limits

Length Width

Inches

72

72

72

72

72

Height

Inches

120

120

120

120

120

Net load

Pounds

500

1,000

2,000

3,000

4,000

Maximum

strut

spacing

(on center)

Inches

54

54

48

48

42

Member sizes of sides

Upper

longitudinal

Inches

Iby 4

Iby 6

Iby 6

1 by 8

1 by 8

Lower

longitudinal

Inches

1 by 4

1 by 4

Iby 6

1 by 6

Iby 8

Intermediate

longitudinal

Inches

1 by 4

1 by 6

1 by 6

1 by 6

1 by 8

Strut

Inches

1 by 42

1 by 6

1 by 6

1 by 6 3

1 by 8

Diagonal

Inches

1 by 4

1 by 4

1 by 4

1 by 6

Iby 6

^^i^gitudinal members shall be in single pieces for lengths

that do not exceed 16 feet, with approved splices permitted

inm lengths i^r.^1.. greater than 16 feet.

2 Edge struts 1 by 6 inch minimum.

3 Edge struts 1 by 8 inch minimum.
68 AGRICULTURE HANDBOOK 2 5 2, U.S. DEPT. OF AGRICULTURE

SKID ASSEMBLIES

Instead of crates, it is soinetinies sufficient to

use heavy skid and cross member assemblies

under large rugged articles such as machine tools,

so that they can be more easily handled and

transported. i i i i

In designing the skid assembly, the length and

width of the item, its weight, type of base, and

its unsupported span (the distance between the

base contacts with the skid) are factors that must

be considered. The number of skids is determined

by the load-carrying capacity of a skid, the

requirements for ^ securing the equipment, and

whether there are any projecting parts. Skids

should be not less than 2 by 4 inches with their

width usually not less than three-fifths of the

depth.

In order to use the tables that give requirements for skids and floorboards, a weight-length

value (WL) must be obtained by multiplying

the actual weight of the item (W) by the unsupported span (i). It is suggested that a sketch

of the skid assembly be made so all factors are

included.

To help in determining the floorboard requirements, the unsupported span, and the skid size,

items have been classified into two groups (fig. 60).

Open-type base articles have two or more legs.

columns, or similar supports, Closed-type base

articles have one support.

SKID SIZES

The length and width of skid assemblies are

usually determined by the overall length and width

of the item. These dimensions include projecting

arms or levers that cannot be further disassembled.

When necessary, additional length must be provided for an end cross member (header) of the same

width and depth as the skid, positioned flatwise.

With the overall measurements known, the proper

L distances can be decided.

In calculating skid sizes, the L value of opentype bases is either the distance from the ends of

of the skids to the base of the item, Li in figures

61, 62, and 63, or one-half the distance between

legs, end frames, or columns, L2 in these figures,

whichever is longer.

With closed-type bases, the L value is either

one-half the distance between floorboards {L2 of

figs. 61, 62, and 63) or the full distance (ZJ from

the end of the skid to the item base, whichever is

longer.

The depths and widths of the members of the

skid assembly may be determined either with

tables 22, 23, and 24 or a formula.

LEG TYPE

\| I END FRAME U

OPEN-TYPE BASES DOUBLE COLUMN

-MI

W^ji^VM.

CIRCULAR

PEDESTAL

RECTANGULAR

COLUMN

RECTANGULAR

COLUMN

IRREGULAR

COLUMN

CLOSED-TYPE BASES

Figure 60.—Typical equipment with bases for which skid assemblies might be designed.

M-l 19723
WOOD CRATE DESIGN MANUAL 69

USE LI OR L2,WHICHEVER

IS LARGER, IN DETERMINING

SKID SIZE.

FLOORBOARD SIZE.

¿j IS USED FOR

Figure 61.—Typical skid assemblies for equipment with open-type bases: A, For leg-type base of equipment without sidewise projections (floorboards not required unless more than two skids are used); B, for double-column-type base, including clearance for

equipment with sidewise projections.

Use of Formula

To determine the skid sizes by formula, either

the depth or the total width of the skids may be

assumed from the material available, and the

formula then solved for the unknown. All skids

in the same assembly should be the same size.

The unknown, when groups II, III, or IV woods

are used, should be determined from the formula :

Tí^í: =33.3 BT)''

where W is total weight of article in pounds; L is

span in feet; B is total width of skids in inches;

and J) is depth of skid in inches.

When group I woods are used, the unknown

dimension should be determined for a load 20

percent greater than the weight of the article.

For example, a 10,000-pound article would be

calculated as 12,000 pounds.

Use of Table

Table 22 gives skid widths and depths for values of

WL from 1,000 to 140,000 foot-pounds. To determine the size of skid required, first find the

proper WL value. Then follow across to the

right to the column that lists the number of skids

required. The skid size at the top of this column

is satisfactory.
70 AGRICULTURE HANDBOOK 2 5 2, U.S. DEPT. OF AGRICULTURE

USE L, OR L2.WHICHEVER

IS LARGER, IN DETERMINING

SKID SIZE. ¿3 IS USED FOR

FLOORBOARD SIZE.

Figure 62.—Typical skid assemblies for equipment with pedestal and similar closed-type bases: A, For equipment without sidewise

projections; B, for equipment with sidewise projections.

USE L, OR L2.^HICHEVER

IS LARGER, IN DETERMINING

SKID SIZE, ¿j IS USED FOR

FLOORBOARD SIZE.

M-l 19908

Figure 63.—Typical skid assemblies for equipment with rectangular or irregular column closed-type bases: A. For rectangular base of

r^lumn hir Í ' ' """^ projections; ß, for rectangular base of equipment without sidewise projections; and C, for irregular

column base of equipment without sidewise projections, showing additional skid
TABLE 22.—Number oj skids required for various loads and sizes of skids

Load in

pounds Skid size and placement

multiplied

by span

in feet

2 by 4

inches,

flat

3 by 3

inches

3 by 4

inches 4 by 4

inches

4 by 6

inches 6 by 6

inches

6 by 8

inches

6 by 10

inches 8 by Í

inches

8 by 10

\ inches 10 by 1(

inches

) 10 by 1^

inches,

edge

512 by 12

inches {WL)

Flat Edge Flat Edge Flat Edge Flat Edge Flat Edge

Foot-pounds

1,000 2

3

3

3

4

4

5

6

1,200 2

2

2

2

3

3

4

5

5

5

6

1,400

1,600

1,800

2,000 2

2

3

\

4

5

5

6

2,500

3,000 2

3

3

3

4

4

5

5

6

3,500

4 000

2

2

3

3

3

4

4

5

5

6

7

8

4,500 2

2

2

3

3

3

3

4

5

5

6

7

8

5,000

6,000

7,000 --

8,000

9,000

10,000

12,000

2

2

3

3

3

4

4

5

5

6

8

8

2

2

14,000

16,000

18,000

20,000

25,000

2

3

3

3

4

4

5

6

7

7

8

2'

2

3

3

3

4

4

5

5

7

8

2~

2 9

30,000

35,000

40,000

2

3

3

4

4

5

6

6

7

8

3

3

4

4

4

5

6

7

7

8

2

2

3

3

3

4

5

5

6

7

2

2

3

3

3

4

4

5

5

6

7

8

45,000 2

3

3

4

4

4

5

6

7

ou,uuu

60,000 2

2

3

3

4

4

5

5

70,000 2'

2

3

3

3

4

80,000 _

90,000--- - 2

2

3

3

100,000 2

120,000

140,000- -- 3

o

o

ö

o

>

m

o

>
72 AGRICULTURE HANDBOOK 2 5 2, U.S. DEPT. OF AGRICULTURE

TABLE 23.—Total vMth required for floorboards bearing loads

Load in pounds multiplied by

Wiflth required when floorboard depth is—

span in feet {WL)

2 inches 3 inches 4 inches 6 inches 8 inches 10 inches 12 inches

Foot-pounds

1,000 - --

Inches

8

10

10

12

14

16

18

22

26

30

34

38

45

54

60

68

76

90

Inches Inches Inches Inches Inches Inches

1,200 -

1,400

1,600

1,800

2,000 6

8

10

12

14

15

17

20

24

26

30

36

40

46

54

60

66

84

100

2,500

3,000

3,500

4,000

4,500 -- - 8

10

11

13

15

17

19

23

26

30

34

38

47

56

66

75

84

94

112

5,000

6,000

7,000

8,000

9,000

10,000 9

10

12

14

15

17

21

25

30

34

38

42

50

58

67

75

84

100

116

12,000

14,000

16,000

18,000

20,000

25,000 12

14

16

19

21

24

28

33

38

42

47

56

66

30,000

35,000

40,000 12

14

15

18

21

24

27

30

36

42

45,000

50,000

60,000

70,000 14

80,000 17

90,000.._ 19

100,000 21

120,000 25

140,000 29 1 "1

TABLE 2^.—SÍ2,^5 of diagonal braces and struts required for skid assemblies

Load

Depth and width required when length of diagonal or strut is—

5 feet 6 feet 7 feet 8 feet 9 feet 10 feet 11 feet 12 feet

Pounds

500 to 1,000

Inches

2 by 4

2 by 4

2 by 6

2 by 6

3 by 4

or

2 by 8

Inches

2 by 4

2 by 4

2 by 6

2 by 8

3 by 4

or

2 by 10

Inches

2 by 4

2 by 6

2 by 8

3 by 4

or

2 bv 8

3 by 4

or

2 by 10

Inches

2 by 6

2 by 6

3 by 4

or

2 bv 8

3 by 4

or

2 bv 10

3 by 6

Inches

2 by 6

3 by 4

or

2 by 8

3 by 4

or

2bv 10

3 by 6

3 by 6

Inches

2 by 6

3 by 4

. or

2 by 10

3 by 4

3 by 6

3 by 8

Inches

3 by 4

or

2 by 8

3 by 4

or

2 by 10

3 by 6

3 by 8

4 by 4

or

3 by 8

Inches

3 by 4

or

2 by 8

3 by 4

1,000 to 2,000

2,000 to 3,000- -

3,000 to 4,000_ .

4 by 4

or

3 by 6

4,000 to 5,000

4 by 4

or

3 by 6

4 by 4

or

3 by 8
WOOD CRATE DESIGN MANUAL 73

If the problem is to determine the number of

skids to use when a certain size material is

available, go to the right of the WL value to the

appropriate skid-size column, which shows at tliis

point the required number of skids.

FLOORBOARD SIZES

Floorboards of uniform thickness sliould be

used in any assembly where all of the skids do not

contact the load, as shown by some of the skid

assemblies in figures 61, 62, and 63. Requirements

for floorboards of groups II, III, or IV woods are

determined from the same formula as are unkno^^^l

skid dimensions:

WL=S3.3 BD2

The difference is that the floorboard span L{Ls in

figs. 61, 62, and 63) is the distance in feet from the

outer edge of the skid to the flange edge of the

article.

Table 23 gives the floorboard requirements for

values of WL from 1,000 to 140,000 foot-pounds.

When group I woods are used, the weight of the

article is increased 20 percent before calculations

are made. The full width, as determined from the

formula or table, should be placed under the base

of the item. No floorboards should be less than

2 by 4 inches.

For items with open-type bases, at least one

floorboard of a skid assembly with more than

two skids should be under each pair of legs or

under each frame or column (fig. 61). The

flooring should be arranged to support all bottom

edges, cross waUs, and ribs of the item that parallel the floorboards. WTien more than one floorboard is required for support, the spacings of the

boards are governed by the requirements for

strength. The fastening bolts should pass through

both skids and floorboards.

When floorboards are required for closed-type

bases (figs. 62 and 63) at least three floorboards

should be used. The anchor bolts should pass

through both skids and floorboards.

DIAGONAL BRACING

Skid assemblies for items with open-type bases

usually require one or more diagonal braces

(fig. 61). The angle of the diagonal with the skids

should be as near 45° as possible but not less than

30° or more than 60°. Diagonals may be fastoned to the upper side of the skids or to the under

side of headers and floorboards. Adjoining diagonals should slope in opposite directions with a strut

between them spanning the assembly. A strut

is not ordinarily needed when the diagonal

bracing is crossed by floorboards or by part of the

item's base. The sizes of these diagonals and

struts are found in table 24.

ASSEMBLY

The fastenings used in skid assemblies are nails,

lag screws, and bolts. Carriage or step bolts are

used to assemble the skids to the end headers. At

each skid contact one bolt should be used when

the header is 5 inches or less in width, and two

bolts when the header is wider than 5 inches.

When the header is less than 3 inches deep, use

bolts % inch in diameter; when 3 to 5 inches deep,

K-inch bolts; and when over 5 inches deep, M-inch

bolts. Boltheads should be flush with the under

sides of the skids.

In fastening the floorboards, diagonals, and

struts to the skids, either bolts or nails may be

used, depending on the thickness of the members.

When 2-inch members are fastened to 2-inch-deep

skids, use two twelvepenny coated or etched nails

for material 4 inches wide and three nails for

members wider than 4 inches. When the diagonals, struts, or floorboards are 2 inches deep and

the skids are deeper than 2 inches, use sixteenpenny nails. When all members are over 2 inches

deep, use carriage or step bolts in the same manner

as outlined for the skid-header connections.

The item should be fastened secm^ely to the

skid assembly with bolts, U-bolts, metal brackets,

or similar fastenings. Lag screws are not recommended for this purpose.

It is good practice to put bolts through the ends

of large skids to prevent them from splitting during

shipment and handling. These bolts are placed

above the center of the skid and about 2}2 inches

from the end.

TESTING CRATES

There can be no absolute standards or rules for

designing crates. For example, while a crate top

may be designed for loads up to 200 pounds per

square foot, it might be subjected to a load of

twice this limit under diflScult storage conditions.

However, because of the safety factors included in

the design, short-time application of such static

loads does not ordinarily cause failure. Nevertheless, it is reasonable to assmiie that some

crates will be subjected to loads that will cause
74 AGRICULTURE HANDBOOK 2 5 2, U.S. DEPT. OF AGRICULTURE

failure. But designing all crates to resist every

stress is not economical. Thus, both design

standards and tests to check them should be

based on conditions to which the majority of

crates are subjected.

The design of a crate may vary greatly for

any item, depending on the means of transportation and the destination. Domestic shipment

of most items will not ordinarily involve as great

or as many hazards as shipment overseas. Consequently, in domestic crates frame members may

be smaller and fastenings less rigid. But some

means should be used to evaluate a newly designed

pilot crate, whether for domestic or export shipment. Tests should simulate actual shipping,

handhng, and storage conditions as closely as

possible in order to determine the suitability of

construction.

M-119683

Fisurc 64.—Rough-handling tests for crates: A, superimposed

load; ß, edgewise drop; C, cornerwise drop; and Ù, pendulum impact.

The development of crate design criteria at the

Forest Products Laboratory led to a series of tests

designed to include those hazards ordinarily

imposed on crates during storage, handling, and

shipping (fig. 64). These tests were used on scores

of containers of all sizes and types, from small open

to large sheathed crates.

The following sections outline the various test

methods that might be used by the designer to

improve crates or to verify construction details.

However, with a crate design based on engineering

principles, a limited crate testing program may be

satisfactory. A good indication of the crate's

adequacy could be gained from superimposed

load, edgewise-drop and cornerwise-drop tests.

SUPERIMPOSED-LOAD TESTS

Superimposed loading may occur during storage

and shipping. When items placed on the top of a

crate are smaller in area than the crate top, the

load must be carried by joists or the top framing

system, which transfer the stresses to the sides

and ends. However, the load of an equal-size

container is carried by the crate sides and ends.

Little, if any, is supported by the joist system.

This may also be true when dunnage is used to

transfer loads to the sides.

The tops of sheathed crates are ordinarily designed to carry superimposed loads, but tops of

open crates are seldom constructed to carry more

than the weight of a man. Inasmuch as most

open crates are used for domestic shipment, there

is little need for costly joist systems adequate to

support loads that ordinarily are not placed on

top without dunnage.

It is suggested that sheathed crates be subjected

to top load tests that place stresses on the joist

system and on the sides and ends. Open crates

may be tested by methods that place the loads only

on the sides and ends.

Top Load Tests for Joists and Framing

Top joists are often designed for loads of 50 to

100 pounds per square foot. Under most conditions a load of 50 pounds per square foot may

be considered as normal, and 100 pounds per

square foot as moderate.

One of the simpler methods of applying loads

to top joist systems without special equipment

is by using sand. If the crate top only is to be

tested, it may be convenient to place the fabricated top, without the sides and ends, on supports

raised a foot or more off the ground. The supports

should be positioned so that the span is the same

as in the assembled crate. A framework of boards

or plywood is then made around the perimeter of

the top, and sand is poured uniformly over the

enclosed area (fig. 65). It is desirable to use

crosstie wires and a membrane such as a plastic
WOOD CRATE DESIGN MANUAL 75.

sheet to prevent the sand from escaping and the

framework from bulging. Sand averages about

100 pounds per cubic foot, so a 6-inch layer would

apply a uniform load of 50 pounds per square

foot; a 12-inch layer, 100 pounds per square foot.

A sample weighing should be made to determine

the exact weight per cubic foot of the sand used.

To increase the test load, loaded boxes may also

be added (fig. 65).

Deflection of the joists may be measured b}^

placing a nail at each end of the joist and stretching a fine wire or string between. By measuring

the distance from the wire to the bottom of the

joist with and without load, the net deflection can

be calculated. Various designs can be compared

by determining the deflection of their joists. The

ultimate strength of the top framing and ' the

joists can be found by adding known increments

of load to the top until it fails.

Testing machines can also be used to test the

tops (fig. 66), but are usualW restricted to testing

narrow panels. Maximum loads can be easily

determined in this type of machine.

Top Load Tests for Sides and Ends

The sides of a crate may be designed to support

top loads of 200 to 400 pounds per square foot.

This is necessary because crates in storage are

often stacked four or more high. When heavy

items are crated, this means tremendous loads are

placed on the lower crate. The tables of sizes

PLYWOOD CRATE TOP

Figure 66.—Testing a narrow crate top in a universal testing

machine. Plywood without a frame is often sufficiently

strong to carry loads over short spans.

for the members of sheathed crates, listed in

Appendix I, cover sides designed to resist top

loads of 200 pounds per square foot in crates used

for items weighing through 10,000 pounds, and

400 pounds per square foot in crates designed for

loads over 10,000 pounds.

To test crates in a manner similar to actual

conditions, it is necessary to place the loads so

LOAD BOXES

SAND

SUPPORT

CRATE TOP

Figure 65.—Testing the framing of a crate top. Loads consist of sand placed to a uniform depth over the surface and the addition of

load boxes.
76 AGRICULTURE HANDBOOK 2 52, U.S. DEPT. OF AGRICULTURE

that they are carried by the sides or by sides and

ends The use of another crate of the same size

would accomphsh this, but with hirge crates this

involves a serious handling problem. Perhaps a

better solution is the use of dunnage, 4- to 6-mchthick timbers, placed on top of the crate across

its \vidth. After the dunnage has been placed,

load boxes are placed uniformly over the surface

by means of a crane or forklift truck. This type

of loadino; will place most of the stresses on the

side panels. Figure 64, A shows a sheathed crate

with a load of large boxes being used to test the

crate sides. The boxes are long enough to span

the width of the crate. Sturdily constructed

boxes filled with sand and securely strapped have

served very well in this type of test. The vertical

deflection of the crate sides is measured when the

load is in place. This test is seldom continued to

failure unless extreme caution is practiced, especially if the crates are large. For smaller crates,

ultimate superimposed loads can be found with a

large testing machine. Figure 67 shows a high,

narrow crate being tested in such a machine.

HANDLING TESTS

Tests have been developed to simulate actual

crate handhng by sling, grabhook, and forklift.

While every crate is not necessarily handled by all

of these methods, crates designed for overseas

shipment should be capable of withstanding all

types of handhng. This is especially true of

sheathed crates, where both grabhook and sling

handling might be used. Much of the handhng

of crates is with forklift trucks, and ordinarily all

crates allow the entry of forklift fingers from both

the sides and ends, through spaces between the

rubbing strips. By allowing side spaces at the

ends as well as at the center of balance, end sling

handling is also possible.

Crater to be tested should contain loads at

least equal to the design loads. The load may

consist of heavy, nailed wood boxes filled with

sand and strapped securely to load-bearing floorboards (fig. 68).

Sling Handling

All crates used for shipping, except perhaps

small, light crates, should include some provision

for being lifted with slings. The skids of large

crates are heavy enough to allow a notch at each

end for the sling. For crates with rubbing strips,

an end space is left at each end of the crate.

Two kinds of slings are ordinarily used to lift and

handle crates aboard ships and in dock areas.

One uses one or more spreader bars to prevent

the crate from being crushed when it is lifted;

the other does not.

If hoisting cables are the only means of lifting

and handling a crate and no siing areas have been

M-l 19686

Fisure 67.—Top loadins a hish, narrow crate. Mechanical

testing machine is applying a top load of 950 pounds per

square foot.

incorporated into the base design, the cables are

often placed around the ends and sides of the crate.

This tends to crush the ends of the crate. When

the cable-only method is used with a short cable,

crushing stresses are placed on base, sides, and

top. The top is especially vulnerable to crushing,

and this is a severe test. Long cables cause less

crushing than short cables. Reinforcing joists,

each positioned where a cable contacts the top

panel, will resist these crushing forces. Figure

69 shows a crate being unloaded with long cables.

The use of large hoisting equipment with a

cable rig is the simplest method of testing a crate
WOOD CRATE DESIGN MANUAL 77

Figure 68.—^Typical load for handling tests. Large boxes filled with sand are strapped to load-bearing floorboards.

with slings. Longitudinal deflection should be

determined by measurements made before and

during the lift. This deflection should be small;

the allowable magnitude varies with the crate

length. When lifting equipment is not available,

an A-frame support may be used. The crate

may be jacked up into position and then lowered

until supported by the slings. Figure 70 shows

a device of this type with the slings looped around

the crate ends. However, for average conditions,

slings placed under each set of skids at the ends

should be satisfactory for this lifting test.

M-119688

Figure 69.—Unloading a crate from ship by means of long cables.

Figure 70.—Loaded test crate supported by slings looped

around the ends of the crate.
78 AGRICULTURE HANDBOOK 2 5 2^ U.S. DEPT. OF AGRICULTURE

Grabhook Handlins

Grabhooks are sometimes employed in handlini;-

erates of small and medium size. Their use should

ordinarily be discouraged because of the eventual

destruction of the crate sheathing at the liftingpoints. Crates with a reinforcing joist in the top

panel at the center of balance can resist grabhook

handling.

A crane or mechanical lifting device with cables

is perhaps most convenient for testing with grabhooks. However, the slings and Á-frame described

in the previous section may be used also. The

loaded test crate should be lifted and supported

with one grabhook located on each side at the

center of balance (fig. 71).

M-119690

Figure 71.—Test crate supported by a single set of grabhooks.

One simple way to measure longitudinal deflection is to drive a nail near each end on one side.

A fishhne or a fine wire is then stretched between

the nails, with a rubberband at one end to keep

the wire taut. Make a mark at the center of the

crate in line with the level measuring wire. When

the crate is lifted, make a second mark; the distance between the two is the bending deflection

caused by the weight of the crate and the contents.

The allowable deflection depends on the length of

the crate and should be minor. Too great a

deflection indicates poor desigTi or construction.

Forklift Handlîns

Handlmg with a forklift truck is becoming more

common even for very large crates. Crates of

light or medium weight are usually lifted from

the sides by forklift trucks, and provisions are

made m crate design for this. Large, heavy crates

are often moved with two forklift trucks by placing tlieii- forklift fingers under each end of the

base. A foi'klift from the side is similar to a grabhook lift at the center of balance. Two forklifts

from the ends is similar to lifting by end slings.

Lifting the loaded test crate from either side places

stresses on the inner and outer skids and indicates the resistance of the skids and other members to this type of lifting. The bending stresses

on the inner skids are transferred to the loadbearing floorboards or other crossmembers. Lifting from the ends with forklift trucks causes bending of the end headers or floorboards.

Aiiy deficiencies brought out by the handhng

t^sts should be corrected by design changes, including, for example, using heavier or properly

located top reinforcing joists, adding filler skids

to accommodate forklift fingers from the sides,

and increasing the size or spacing of end headers

in the base. Tests on pilot crates will bring out

any weaknesses that need to be corrected in order

to minimize damages to crates.

DROP AND IMPACT TESTS

Crates handled with a variety of equipment

and under many conditions are often subjected

to accidental drops. A lifting device may be released too fast, resulting in a corner impact, or a

crate may skid off a truck, impacting one edge.

An end impact may result when a swinging crate

is let down with slings. All crates are not subjected to these hazards, but it is important that

the crate design include sufficient strength to resist them. Drop tests of some type should be

incorporated in the testing program, because impacts caused by drops are severe and can result

in member damage and fastening failures. The

three general tests that simulate impacts to crates

and are ordinarily used to test crates are (1) the

edgewise-drop, (2) the cornerwise-drop, and (3)

the pendulum-impact tests (fig. 64).

Drop tests are reasonably simple to conduct

and require only a minimum amount of equipment. As in the Imndling tests, the test crate

should contain a load similar in weight to the

item for which the crate is designed. Nailed wood

boxes filled with sand are satisfactory. After the

test loads are anchored inside, the crate is completely assembled with the correct number, size,

and spacing of fasteners for the design.

Edsewise-Drop Test

The edgewise-drop test is conducted by first

placing one end of the base of the test crate on a

5- or 6-inch-square timber sill. The opposite end

is then raised to a predetermined height and

allowed to fall freely to a level concrete floor or

slab. The end of the crate may be raised by a

hoist with a quick-release device attached that
WOOD CRATE DESIGN MANUAL 79

can be triggered from a safe distance (fig. 64, B).

Or the raised end of the crate may be phxced on

a wood block of the proper length with a chain or

cable attached. A truck or other mechanical device is used to pull out the block quickly, permitting the end of the crate to drop to the concrete

slab.

A series of drop heights, similar to those used

in testing programs at the Forest Products Laboratory, is shown in table 25. The height of drop

is selected that will meet the requirements for

both the gross weight and dimensions of the crate.

For example, a crate that weighs less than 600

pounds but has a dimension over 72 inches will

be dropped from 24 inches if for overseas shipment and 18 inches if for domestic.

TABLE 25.—Drop heights for edgemse and cornerwise drop tests of crates of various weights and

lengths

Height of drop for lengths of—

Gross weight

(crate and

contents)

Up to 72 inches Over 72 inches

(pounds) Overseas

DomesticOverseasDomestic

Up to 600

600 through 3,000__

Over 3,000

Inches

36

24

12

Inches

27

18

9

Inches

24

24

12

Inches

18

18

9

The test crate should be dropped on each end.

Longitudinal deflection measurements should be

made before and after the drops to determine the

amount of residual deflection. Careful notes

should be made of broken members, spHts, and

nailpulls. The edgewise-drop test not only places

bending stresses on the crate as a whole, but also

is a positive test for side-to-base fastenings and for

the load-bearing floorboards. The data assembled

from the tests will guide the designer in improving

the crate.

Cornerwise-Drop Test

The cornerwise-drop causes severe racking

stresses in all panels of the crate, impact of the

corner, and bending stresses similar to those in

edgewise drops.

A block is placed on one end of the sill so that

one supported corner is 5 to 6 inches higher than

the other supported corner. The opposite end is

then raised to a height designated in table 25 and

allowed to fall freely (fig. 64, C^. The corner diagonally opposite the corner block strikes the concrete slab first. As in the edgewise-drop test the

crate should be dropped on each end, and the

692-318 0—64 6

deflection measurements and other data on failures

and reactions of parts of the crate should be

compiled.

Pendulum-Impact Test

The pendulum-impact test is primarily intended

as a test of the blocking and bracing of the item

in the crate. It also stresses the bolts used to

fasten the load-bearing floorboards to the skids.

It simulates not only accidental impacts of a crate

swinging on slings, but also the humping that

occurs in the switching of railway cars.

The pendulum-impact test requires some type

of suspended platform or sling to hold the crate.

This platform is suspended with at least four

parallel cables or chains about 20 to 24 feet in

length (fig. 64, Z)). ^¥hen suspended the platform

should be parallel to the floor with a 3- or 4-inch

clearance. The backstop may be concrete or a

large timber rigidly secured. The crate is placed

so that it rests lightly against the backstop when

the platform is freely suspended. The platform

is pulled back from the backstop until the crate is

raised 9 inches. Then it is released and aUowed

to swing freely against the backstop. Each end

is tested with one impact in this manner. The

freight car speed that gives an impact equivalent

to the 9-inch pendulum test is about 7 miles per

hour.

A variation of the described test would be to

conduct it with a load or another crate on top

of the test crate. This would create severe racking stresses on the sides and on the side-to-end

nailing and other fastenings.

The notes, measurements, and other data

gathered during the series of crate tests, together

with general observations, are usually sufficient to

determine the adequacy of the design. When

necessary, details of the design may be changed,

incorporated into the test crate, and retested. It

may be necessary to repeat only one or two phases

of the test schedule. For example, if the fastenings of the sides to the base failed during the edgewise-drop tests, the spacing and location would be

changed or a different type of fastener used. The

changed test crate would then be subjected only

to the edgewise-drop test if the other tests had

been passed.

These tests were designed to reveal any major

weakness in the crate parts or in the fabrication

and assembly methods. Other tests may be used,

but each should be developed to simulate some

phase of handling or storage that creates special

hazards not covered here. Of course, not all

conditions a crate might encounter can be anticipated, and it would not be economical to design

a crate to resist all real and theoretical hazards.

However, a good testing program used in the development of new crate designs will more than pay

for itself.
APPENDIX I. PANEL MEMBER SIZES

Panel member sizes for crates of various dimensions, designed to carry loads through 30,000 pounds,

are given in tables 26 through 35.

TABLE 26.—Panel member sizes jor crates^ designed jor a net load oj IfiOO pounds

4-FOOT-WIDE CRATE

Length Member

Crate height

2 feet 4 feet 6 feet 8 feet 10 feet 12 feet

Ft.

rUpper frame _ _

In.

il by 4

1 by 4

1 by 4

Iby 4

1 by 4

1 by 4

(2)

(?)

{')

(')

(')

(')

(')

{')

{')

(2)

(')

{')

{')

(')

{')

{')

(')

{')

{')

(')

{')

(')

(')

(')

(')

In.

Iby 4

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

Iby 4

1 by 4

ilby 4

1 by 4

1 by 4

1 by 4

Iby 6

Iby 4

Iby 4

1 by 4

In.

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

Iby 4

1 by 4

1 by 4

1 by 4

1 by 4

Iby 4

In.

1 by 4

Iby 4

1 by 4

Iby 4

1 by 4

Iby 4

1 by 4

1 by 4

1 by 4

1 by 6

Iby 4

1 by 6

Iby 4

1 by 6

1 by 4

Iby 6

fl by 4

Iby 4

Iby 4

Iby 6

In.

Iby 4

Iby 4

1 by 4

1 by 4

Iby 4

1 by 4

Iby 4

Iby 4

Iby 4

Iby 4

1 by 4

Iby 4

Iby 4

Iby 4

Iby 4

1 by 4

Iby 4

In.

Lower frame _ _ _

6

' Strut 1 by 4

DiagonaL ._ _ _ _ _

[Upper frame __ _ _

Lower frame 8

¡Strut- . _

1 by 4

DiagonaL- . _

Í Upper frame._

Lower frame.. 10 1 Strut-__ - --

1 by 4

Diagonal _ _

r Upper frame

Lower frame._ 12 Strut--_ -- -

1 by 4

Diagonal _

rUpper frame _ _. _

Lower frame . .

16 ]Strut- -

1 by 4

Diagonal

("Upper frame

Lower frame. ._ 20 Strut 1 by 4

Diagonal

[Upper frame

nM Lower frame 24 Strut Iby 4

Diagonal.- .

[Upper frame.__

28 Lower frame...

Strut Iby 4

Diagonal.. _.

[Upper frame.__

32 Lower frame... Iby 4

Strut

Diagonal.- - Iby 4

Upper frame.

36 Lower frame. _. Iby 4

Strut

Diagonal 1 by 4

[Upper frame...

40 Lower frame.. Iby 4

Strut

.Diagonal Iby 4

[Upper frame.__

44 Lower frame.- Iby 4

Strut

Diagonal Iby 4

[Iby 4

Iby 4

Iby 4

Iby 6

fUpper frame...

48 Lower frame..

Strut

Diagonal

See footnotes at end of table.

80
WOOD CRATE DESIGN MANUAL 81

TABLE 26.—Panel member sizesfor crates ^ designed for a net load of 1,000 pounds—Continued

6-FOOT-WIDE CRATE

Length Member

Crate height

2 feet 4 feet 6 feet 8 feet 10 feet 312 feet

Ft.

10

12

16

20

24

28

32

36

40

44

48

iUpper frame..

Lower frame. _

Strut

Diagonal

IUpper frame..

Lower frame. _

Strut

Diagonal

Upper frame..

Lower frame..

Strut

Diagonal

Upper frame..

Lower frame..

Strut

Diagonal

Upper frame..

Lower frame..

Strut

Diagonal

Upper frame..

Lower frame..

Strut

Diagonal

Upper frame..

Lower frame.

IStrut

[Diagonal

iUpper frame.

Lower frame..

Strut

Diagonal

Upper frame.

Lower frame.

Strut

Diagonal

Upper frame.

Lower frameStrut

Diagonal

Upper frame.

Lower frame.

Strut

Diagonal

Upper frame.

Lower frameStrut

Diagonal

Upper frame.

Lower frame.

Strut

Diagonal

In.

1 by 4

by 4

1 by 4

1 by 4

a by 4

1 by 4

{')

(')

{')

{')

{')

{')

(')

{')

{')

{')

{')

{')

{')

{')

{')

{')

{')

(')

{')

(')

{')

(')

(')

{')

{')

(')

(')

In.

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

[l by 4

1 by 4

1 by 4

[l by 4

1 by 4

1 by 4

[l by 4

1 by 4

1 by 4

h by 4

1 by

1 by

1 by

1 by

1 by

1 by

1 by

1 by

1 by 6

1 by 4

1 by 6

1 by 4

1 by 6

1 by 4

In.

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

a by 4

In.

1 by 4

1 by 4

1 by 4

Iby 4

1 by 4

1 by 4

1 by 4

1 by 6

1 by 4

1 by 4

1 by 6

1 by 4

1 by 4

1 by 6

1 by 6

1 by 4

1 by 6

1 by 6

2 by 4

2 by 4

2 by 4

In.

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

Iby 4

1 by 4

Iby 4

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

In.

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

1 bv 6

2 by 4

2 by 4

See footnotes at end of table.
32 AGRICULTURE HANDBOOK 252, U.S. DEPT. OF AGRICULTURE

TABLE 2&.-Panel member sizesfor crates ^ des^gnedfor a net load of 1 flOO pounis-Conúnu^á

8-FOOT-WIDE CRATE

Length

Ft

12

16

20

24

28

32

36

40

44

48

Member

[Upper frame__

I Lower frame_-

Strut-_-

[Diagonal

¡Upper frame.-

Lower frame. _

Strut

Diagonal

[Upper frame.-

Lower frame._

Strut

(.Diagonal

¡Upper frame.-

Lower frame..

Strut___

Diagonal-----

¡Upper frame--

Lower frame..

Strut

Diagonal

IUpper frame--

Lower frame..

Strut---

Diagonal.----

IUpper frame. _

Lower frame..

Strut

Diagonal--—

IUpper frame..

Lower frame. .

Strut

Diagonal

IUpper frame..

Lower frame..

Strut

Diagonal.----

(Upper frame..

Lower frame..

Strut---

Diagonal

IUpper frameLower frameStrut

Diagonal

IUpper frameLower frameStrut

Diagonal----

I Upper frameJ Lower frame.

Strut

[Diagonal

Crate height

2 feet

In.

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

I by 4

{')

(?)

{')

{')

{')

{')

{')

{')

(')

(')

{')

(')

{')

{')

{')

(')

{')

(')

(')

{')

(')

{')

{')

{')

{')

{')

(')

{')

4 feet

In.

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

by 4

by 4

by 6

by

by

by

by

by

1 by

1 by

1 by 6

1 by 4

1 by 6

1 by 4

1 by 6

1 by

1 by

1 by

1 by

1 by

1 by

1 by

1 by

1 by

2 by

1 by

1 by

Iby

6 feet

In.

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

[l by 4

1 by 4

4 by 4

1 by

Iby

1 by

1 by

1 by

1 by

1 by

1 by

2 by

1 by

Iby

1 by

8 feet

In.

1 by 4

1 by 4

1 by 4

1 by 4

ilby 4

I Iby 4

1 by 6

1 by 4

1 by 4

1 by 4

1 by 6

1 by 4

Í1 by 4

1 by 4

Iby 6

1 by 6

1 by 4

1 by 4

1 by 8

U by 6

2 by 4

» 10 feet

In.

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

[iby 4

1 by 4

•1 by 4

1 by 4

Ílby4

1 by 4

1 by 4

UbyB

1 by 6

1 by 4

Iby 4

Iby 6

flby 6

Iby 4

1 by 4

1 by 6

Iby 6

1 by 4

1 by 4

Iby 6

12 feet

In.

2 by 4

2 by 4

2 by 4

1 by 4

2 by 4

2 by 4

2 by 4

Iby 4

2 by 4

by 4

by 4

by 4

by 4

by 4

by 4

Iby 4

2 by 4

by 4

by 4

by 4

by 4

by 4

by 4

by 4

[2 by 4

2 by 4

2 by 4

1 by 4

2 by 4

2 by 4

2 by 4

1 by 6

2 by 4

.2 by 4

^2bv4

2 by 4

2 by 4

See footnotes at end of table.
WOOD CRATE DESIGN MANUAL 83

TABLE 26.—Panel member sizesJor crates ' designed for a net load oj 1,000 pounds—Continued

10-FOOT-WIDE CRATE

Length

Ft.

10

12

16

20

24

28

32

36

40

44

48

Member

Upper frameLower frame.

Strut

Diagonal

Upper frame.

Lower frame.

Strut

Diagonal

Upper frameLower frameStrut

Diagonal

Upper frameLower frameStrut

Diagonal

Upper frame.

Lower frameStrut

I Diagonal

i Upper frameLower frameStrut

Diagonal

I Upper frameLower frame.

Strut

Diagonal

iUpper frame.

Lower frame.

Strut

Diagonal

i Upper frame.

Lower frameStrut

Diagonal

IUpper frame.

Lower frame.

Strut

Diagonal

i Upper frame.

Lower frameStrut

Diagonal

IUpper frame.

Lower frame.

Strut

Diagonal

I Upper frameLower frameStrut

Diagonal

Crate height

2 feet 4 feet

In.

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

(')

e)

(')

{') e)

(')

(') e)

(') e)

(')

(')

(')

(')

(')

(') e)

(')

(')

(')

(')

(')

(')

6 feet

In.

1 by 4

1 by 4

1 by 4

Iby 4

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by 8

by 4

by 4

by 4

by 8

by 4

by 4

by 4

by 8

by 4

by 6

by 4

by 8

by 4

In.

1 by 4

1 by 4

1 by 4

1 by 4

Iby 4

Iby 4

1 by 4

Iby 4

by

by

by

by

by

by

by

4

4

6

4

6

4

6

1 by 4

1 by 6

1 by 4

by

by

by

by

by

by

by

by

by

by 6

8 feet

In.

1 by 4

by 4

by 4

by 6

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by 8

by 6

by 4

by 4

by 8

by 6

2 by 4

>2by 4

2 by 4

2 by 4

|2by 4

2 by 6

2 by 4

2 by 4

2 by 4

10 feet

In.

2 by

2 by

2 by

1 by

2 by

2 by

2 by

1 by

2 by

2 by

2 by

Iby

^by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

1 by

[2 by

2 by

[2 by

[iby

2 by

l2by

2 by

[iby 6

2 by 4

12 by 4

2 by 4

[iby 6

2 by 4

2 by 4

2 by 6

2 by 4

2 by 4

2 by 4

12 feet

In.

by 4

by 4

by 4

1 by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

2 by 4

2 by 4

2 by 4

by 4

by 4

by 4

by 6

by

by

by

by

by

by

by

by

' With horizontal joist supports, except as indicated.

^ Crates require special design.

' Crates require 2 by 4 vertical joist supports when struts are 1 inch thick.
84 AGRICULTURE HANDBOOK 2 5 2, U.S. DEPT. OF AGRICULTURE

TABLE 27.—Panel member sizes jor crates^ designed jor a net load oj 2fi00 pounds

4-FOOT.WIDE CRATE

Length Member

Crate height

2 feet 4 feet 6 feet 8 feet 10 feet 12 feet

Ft.

10

12

16

20

24

28

32

36

40

44

48

Upper frame.

Lower frame.

1 Strut

[Diagonal

I Upper frame.

Lower frame.

Strut

Diagonal

Upper frame.

Lower frame.

Strut

Diagonal

Upper frame.

Lower frame.

Strut

Diagonal

Upper frame.

Lower frame.

Strut

Diagonal

r Upper frame.

I Lower frame.

Strut

[Diagonal

Upper frame.

Lower frame.

Strut

Diagonal

Upper frame.

Lower frame..

Strut

Diagonal

Upper frame.

Lower frame..

Strut

Diagonal

Upper frame..

Lower frame.

Strut

.Diagonal

Upper frame..

Lower frame..

Strut

.Diagonal

I Upper frame..

Lower frame..

Strut

Diagonal

'Upper frame..

Lower frame..

Strut

Diagonal

In.

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

(')

e)

{')

(')

(')

(')

{')

{')

{')

{')

{')

{')

{')

{')

(')

{')

(')

{')

0)

{')

i')

{')

In.

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

1 bv 4

1 by 6

1 bv 4

1

1

1

1

by

by

by

by

1 by

Iby

1 by

1 by

1 by

1 by

1 by

1 by

1 by

1 by

2 by

1 by

1 by

1 by

In.

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

•1 by 4

1 by 4

1 by 4

1 by 6

1 by 4

1 by 4

1 by 4

1 by 6

1 by 4

1 by 4

1 by 4

In.

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

2 by 4

See footnotes at eod of table.

In.

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

Iby 4

1 by 4

1 by 4

Iby 4

Iby 4

In.

1 by 4

1 by 4

1 by 4

Iby 4

1 by 4

Iby 4

1 by 4

1 by 4

Iby 4

1 by 4

1 by 4

Iby 4

1 bv4

Iby 4

Iby 6

1 bv4

1 by 4

Iby 4

.Iby 6
WOOD CRATE DESIGN MANUAL 85

TABLE 27.—Panel member sizesjor crates ^ designedjor a net load oj2ft00 pounds—Continued

6-FOOT-WIDE CRATE

Length

Ft.

10

12

16

20

24

28

32

36

40

44

48

Member

Upper frameLower frameStrut

, Diagonal

Upper frameLower frameStrut

Diagonal

Upper frameLower frameStrut

Diagonal

Upper frameLower frameStrut

Diagonal

Upper frameLower frameStrut

Diagonal

Upper frameLower frameStrut

Diagonal

Upper frameLower frameStrut

Diagonal

Upper frameLower frameStrut

[Diagonal

iUpper frameLower frameStrut

Diagonal

IUpper frameLower frameStrut

Diagonal

iUpper frameLower frameStrut

Diagonal

IUpper frameLower frameStrut

Diagonal

IUpper frameLower frameStrut

Diagonal

Crate height

2 feet

In.

1 by 4

1 by 4

1 by 4

Iby 4

1 by 4

Iby 4

{')

{')

{')

{')

{')

{')

{')

{')

{')

i})

{')

{')

{')

{')

{')

{')

{')

(2)

{')

i?) e)

{')

{')

{')

{')

{')

{')

(?)

4 feet

in.

Iby 4

Iby 4

1 by 4

1 by 4

1 by 4

1 by 4

a by 4

^1 by 4

1 by 6

Iby 4

1 by 4

1 by 4

1 by 6

1 by 4

1 by 6

1 by 4

1 by 6

Iby

1 by

1 by

2 by

1 by

1 by

1 by

2 by

1 by

1 by

1 by

6 feet 8 feet

In.

1 by 4

1 by 4

Iby 4

Iby 4

Iby 4

Iby 4

Iby 4

Iby 4

a by 4

In.

1 by 4

1 by 4

1 by 4

Iby 4

Iby 4

Iby 4

Iby 4

Iby 4

Iby 6

1 by 6

1 by 4

1 by 4

Iby 6

.Iby 6

2 by 4

10 feet

In.

Iby 4

1 by 4

Iby 4

Iby 4

Iby 4

1 by 4

•1 by 4

\ by 4

Iby 4

Iby 4

'12 feet

In.

1 by 4

Iby 4

1 by 4

1 by 4

1 by 4

Iby 4

1 by 4

Iby

1 by

Iby

Iby

Iby

1 by

Iby

.Iby 6

1 by 4

1 by

1 by

.Iby

1 by

1 by

1 by

Iby

^2 by 4

^2 by 4

See footnotes at end of table.
86 AGRICULTURE HANDBOOK 2 5 2, U.S. DEPT. OF AGRICULTURE

TABLE 27.—Panel member sizes for crates ^ designedjor a net load oj2,000 pounds—Continued

8-FOOT-WIDE CRATE

Length

Ft.

10

12

16

20

24

28

32

36

40

44

48

Member

Upper frame.

Lower frame_

Strut

Diagonal

Upper frameLower frameStrut

Diagonal

Upper frameLower frameStrut

Diagonal----.

Upper frameLower frame.

Strut---

.Diagonal

Upper frameLower frameStrut

Diagonal

Upper frame-.

Lower frame..

Strut---

Diagonal

Upper frame..

Lower frame..

Strut--.

Diagonal

Upper frame..

Lower frame..

Strut

Diagonal

Upper frame..

Lower frame..

Strut

Diagonal.-

Upper frame-.

Lower frame-.

Strut

Diagonal.-

Upper frame-.

Lower frame-.

Strut

Diagonal

Upper frame-.

Lower frame..

Strut

Diagonal

Upper frame..

Lower frame._

Strut

Diagonal

Crate height

2 feet

See footnotes at end of table.

In.

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

{')

(')

{')

{')

{')

{')

{')

{')

(')

{')

(')

{')

(')

(')

{')

(')

(')

(')

4 feet

In.

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

1 by 6

1 by 4

Iby 6

1 by 4

1 by 6

1 by 4

1 by 6

1 by 4

by

by

by

by

by

by

1 by

1 by

2 by

1 by

1 by

1 bv

2bv

Iby

1 by

1 by

2 by

1 by

1 by

Iby

6 feet

In.

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

1 by 6

1 by 4

Iby 4

1 bv 4

1

1

1

1

1

1

1

1

1

1

1

1

2

by 6

by

by

by

by

by

by

by

by

by

by

bv

by

1 by

1 by

1 by

8 feet

In.

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

1 by 6

.1 by 6

1 by 4

1 by 4

1 bye

.1 by 6

2 by 4

2 by 4

2 by 4

^2 by 4

2 by 4

•2 by 4

2 by 4

310 feet

In.

1 by 4

1 by 4

2 by 4

2 by 4

12 feet

In.

2 by 4

2 by 4

2 by 4

U by 4

'2 by 4

2 by 4

2 by

Iby

2 by

2 by

2 by

1 by

2 by

2 by

2 by

Iby

2 by

2 by

2 by

1 by

2 by

2 by

2 by 4

Iby 6

2 by 4

2 by 4

2 by 4

Iby 6

2 by 4

'2 by 4

•2 by 4

2 by 4

2 by 4

2 by 4

2 by 4

2 by 4

2 by 6
WOOD CRATE DESIGN MANUAL 87

TABLE 27.—Panel member sizes for crates ^ designedfor a net load of 2,000 pounds—Continued

lO-FOOT-WIDE CRATE

Length Member

Crate height

2 feet 4 feet 6 feet 8 feet 10 feet 12 feet

Ft.

10

12

16

20

24

28

32

36

40

44

48

IUpper frame.

Lower frame.

Strut

Diagonal

IUpper frame.

Lower frame.

Strut

Diagonal

¡Upper frame.

Lower frame.

Strut

Diagonal

IUpper frameLower frame.

Strut

Diagonal

IUpper frameLower frameStrut

Diagonal

IUpper frame.

Lower frame.

Strut

Diagonal

Upper frame.

Lower frame.

Strut

Diagonal

Upper frame.

Lower frameStrut

, Diagonal

Upper frame.

Lower frame.

Strut

Diagonal

Upper frame.

Lower frameStrut

^Diagonal

Upper frameLower frameStrut

.Diagonal

Upper frameLower frameStrut

.Diagonal

Upper frameLower frameStrut

.Diagonal

In.

1 by 4

Iby 4

1 by 4

Iby 4

1 by 4

1 by 4

{')

{')

(')

{')

{')

(')

{')

(')

{')

(')

{')

{')

{')

(')

{')

{')

(')

{')

{')

{')

{')

{')

(')

{')

{')

i')

In.

1 by 4

1 by 4

1 by 4

1 by 4

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by 8

by 4

by 6

by 4

by 8

by 4

by 6

1 by 4

by 8

by 4

by 6

by 6

by 8

by 4

In.

1 by 4

1 by 4

1 by 4

Iby 4

1 by 4

1 by 4

Iby 4

1 by

by

by

by

by

by

by

by 6

by 6

by

by

by

by

by

1 by

by

by

by

by 6

by 6

by 6

by 4

by 4

by 4

In.

Iby 4

2 by 4

2 by 4

by 6

In.

2 by 4

2 by 4

2 by 4

1 by 4

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

2 by 4

2 by 4

2 by 4

2 by 4

2 by 6

2 by 4

2 by 4

2 by 6

In.

by

by

by

by

by

by

by

by 4

by 4

by

by

by

by

by

by

by

by

by

by

by

by 4

by 4

by 4

by 6

2 by 4

2 by 4

2 by 4

by

by

by

by

by

by

by

by

by

by

by

by 6

by 6

by 4

by 4

by 6

^ With horizontal joist supports, except as indicated.

^ Crates require special design.

^ Crates require 2 by 4 vertical joist supports when struts are 1 mch thick.
88 AGRICULTURE HANDBOOK 2 5 2, U.S. DEPT. OF AGRICULTURE

TABLE 28.—Panel member sizes Jor crates^ designed for a net load oj 4fiOO pounds

4-FOOT-WIDE CRATE

Length Member

Ft.

10

12

16

20

24

28

32

36

40

44

48

i Upper frame.

Lower frame.

Strut

Diagonal

(Upper frame.

Lower frame.

Strut

Diagonal

r Upper frame.

J Lower frameStrut

[Diagonal

ILTpper frame.

Lower frame..

Strut

Diagonal

Upper frame..

Lower frame..

Strut

[Diagonal

rUpper frame..

J Lower frame..

Strut

[Diagonal

I Upper frame..

Lower frame..

Strut

Diagonal

[Upper frame..

J Lower frame.-

Strut

I Diagonal

IUpper frame..

Lower frame..

Strut

Diagonal

I Upper frame. _

Lower frame..

Strut

Diagonal

iUpper frame..

Low^er frame..

Strut

Diagonal

iUpper frame..

I Lower frame._

Strut

[Diagonal

IUpper frame..

Lower frame._

Strut

Diagonal

Crate height

2 feet

In.

1 by 4

1 by 4

n by 4

Iby 4

by

by

by

by

by

by 4

by 4

by 4

{')

{')

{')

{')

{')

{')

(')

{')

{')

{')

{')

{')

(')

{')

(')

{')

(')

{')

{')

(')

(')

(')

{')

(')

{')

4 feet

In.

1 by 4

1 by 4

1 by 4

1 by 4

>1 by 4

•1 by 4

1 by 6

1 by 4

1 by 4

1 by 4

1 by 6

1 by 4

1 by 4

1 by 4

2 by

Iby

1 by

1 by

2 by

1 by

1 by

1 by

2 by

1 by

1 by

by

bye

by

by

by

by

by

by

Iby

6 feet

In.

1 by 4

1 by 4

1 by 4

1 by 4

Iby 4

1 by 4

a by 4

a by 4

Iby 4

1 by 6

1 by 4

1 by 4

1 by 4

1 by 6

4

4

4

6

4

4

4

6

4

4

4

1 by

1 by

1 by

1 by

1 by

1 by

1 by

2 by

1 bv

1 by

Iby

12 feet

See footnotes at end of table.

1 by 4

Iby 4

Iby 4

Iby 6

Iby 4

Iby 4

Iby 4

1 by 6

Iby 4

Iby 4

Iby 4

Iby 6

2 by 4
WOOD CRATE DESIGN MANUAL 89

TABLE 28.—Panel member sizesjor crates ^designedfor a net load oj4)000 pounds—Continued

e-FOOT-WIDE CRATE

Length

FL

10

12

16

20

24

28

32

36

40

44

48

Member

'Upper frame

Lower frame

Strut

^ Diagonal

Upper frame

Lower frame

Strut

.Diagonal

'Upper frame

Lower frame

Strut

, Diagonal

Upper frame

Lower frame

Strut

L Diagonal

Upper frame

Lower frame

Strut

[Diagonal

'Upper frame

Lower frame

Strut

. Diagonal

'Upper frame

Lower frame

[Strut

, Diagonal

'Upper frame

Lower frame

Strut

[Diagonal

[Upper frame

I Lower frame

I Strut

[Diagonal

[Upper frame

I Lower frame

I Strut

[Diagonal

[Upper frame

I Lower frame

[Strut

[Diagonal

Upper frame

I Lower frame

I Strut

[Diagonal

[Upper frame

I Lower frame

I Strut

[Diagonal

Crate height

2 feet

In.

>1 by 4

a by 4

a by 4

a by 4

1 by

1 by

1 by

1 by

1 by

Iby

by

by

(')

{')

(')

i')

(')

{')

i')

(')

{')

(')

i')

i')

i')

{')

P)

(')

(')

0)

i')

{')

(')

0)

4 feet

In.

1 by 4

Iby 4

1 by 4

Iby 4

Iby 4

1 by 4

1 by

1 by

by

by

by

by

by

by

by

by

Iby

1 by

2 by

1 by

1 by

Iby

2 by

Iby

by

by

by

by

by 6

by 4

by 8

1 by 6

1 by 6

1 by 4

6 feet

In.

Iby 4

1 by 4

Iby 4

1 by 4

Iby 4

Iby 4

a by 4

1 by 4

1 by

1 by

Iby

by

by

by

by

by

by

by

by

by

2 by

1 by

1 by

Iby

2 by

1 by

1 by

1 by 6

8 feet

In.

Iby 4

2 by 4

2 by 4

^2 by 4

2 by 4

2 by 4

2 by 4

2 by 4

10 feet

In.

1 by 4

a by 4

1 by 4

•1 by 4

1 by 4

1 by 4

Iby 4

1 by 4

312 feet

In.

1 by 4

1 by 4

Iby 4

Iby 4

Iby 4

1 by 4

1 by 4

1 by 4

1 by 4

1 by 6

Iby 4

1 by 4

Iby 4

Iby 6

•2 by 4

'2 by 4

>2 by 4

^2 by 4

2 by 4

See footnotes at end of table.
QQ AGRICULTURE HANDBOOK 2 5 2, U.S. DEFT. OF AGRICULTURE

TABLE 2S.—Panel member sizesfor crates ' designedJor a net load of 4,000 pounds—Contmned

8-FOOT-WIDE CRATE

Length Member

FL

10

12

16

20

24

28

32

36

40

44

48

Upper frame..

Lower frame..

Strut---

.Diagonal

Upper frame.-

Lower frame..

Strut---

.Diagonal

'Upper frame..

Lower frame..

Strut---

,Diagonal.-—

Upper frame..

Lower frame..

Strut

.Diagonal

'Upper frame..

Lower frame..

Strut

Diagonal

Upper frame..

Lower frame..

Strut

.Diagonal

Upper frame..

Lower frame.,

Strut

.Diagonal

'Upper frameLower frameStrut

Diagonal

Upper frame.

Lower frame.

Strut

^Diagonal

'Upper frame.

Lower frameStrut

.Diagonal

Upper frameLower frameStrut

,Diagonal

' Upper frame.

Lower frame.

Strut

Diagonal. _--

'Upper frame.

Lower frame.

Strut

.Diagonal

2 feet

In.

1 by 4

1 by 4

1 by 4

1 by 4

by

by

by

by

by

Iby

1 by 4

1 by 4

{')

(')

{')

(')

{')

{')

0)

(')

(')

(')

(')

(')

{')

(')

(')

{')

(')

(')

P)

(')

{')

{')

{')

(')

{')

P)

{')

4 feet

In.

1 by 4

1 by 4

1 by 4

1 by 4

•1 by 4

>1 by 4

1 by 6

1 by 4

1 by 6

1 by 4

1 by 6

1 by 4

Iby 6

1 by 4

2 by

Iby

1 by

1 by

2 by

1 by

Iby 6

1 by 4

2 by 6

Iby 6

6

4

6

4

6

4

by 6

by 4

by 6

by 6

by 6

by 4

by 8

by 4

by 6

by 4

Crate height

6 feet

In.

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

by 6

by

by

by

by

by

by

Iby 4

1 by 6

1 by 4

1 by 4

1 by 6

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

8 feet

In.

1 by 4

1 by 4

Iby 4

1 by 4

.Iby 6

2 by 4

1 by 4

1 by 4

1 by 4

Iby 6

2 by 4

2 by 4

2 by 4

2 by 4

^2 by 4

^2 by 4

2 by 4

2 by 4

2 by 4

2 by 4

2 by 6

2 by 6

2 by 4

2 by 4

2 by 6

310 feet

Iby 4

1 by 4

Iby 4

2 by 4

2 by 4

2 by 4

2 by 6

2 by 4

2 by 4

2 by 4

12 feet

In.

2 by 4

2 by

2 by

Iby

2 by

2 by

by

by

by

by

by

1 by

2 by

2 by

2 by

Iby

2 by

2 by

2 by

Iby

2 by

2 by

2 by 4

Iby 6

2 by 4

í2by.4

2 by 4

2 by 4

2 by 4

'2 by

2 by

2 by

.2 by

2 by

2 by

2 by

2 by

See footnotes at end of table.
WOOD CRATE DESIGN MANUAL 91

TABLE 28.—Panel member sizesfor crates ^ designedJor a net load oJ4fiOO pounds—Continued

10-FOOT-WIDE CRATE

Length

Ft.

10

12

16

20

24

28

32

36

40

44

48

Member

IUpper frame

Lower frame

Strut

Diagonal

1Upper frame.

Lower frame.

Strut

Diagonal

fUpper frame.

I Lower frame

] Strut

[Diagonal

IUpper frame.

Lower frame.

Strut

Diagonal

1 Upper frame.

Lower frame

Strut

Diagonal

iUpper frame

Lower frame

Strut

Diagonal

IUpper frame

Lower frame

Strut

Diagonal

IUpper frame

Lower frame

Strut

Diagonal

IUpper frame

Lower frame

Strut

Diagonal

IUpper frame

Lower frame

Strut

Diagonal

IUpper frame

Lower frame

Strut

Diagonal

IUpper frame

Lower frame

Strut

Diagonal

IUpper frame

Lower frame

Strut

Diagonal

Crate height

2 feet

In.

1 by 4

•1 by 4

4 by 4

-1 by 4

Iby

by

by

by

by

by

by

by

(')

{')

(')

{')

(')

{')

{')

{')

{')

{')

{')

{')

{')

(')

(')

{')

{')

{')

(')

{')

{')

{')

(')

{')

{')

{')

{')

4 feet

In.

1 by 4

1 by 4

1 by 4

1 by 4

by

by

by

by

by

by

by

by

by

by

by 6

by 4

by 4

by 4

by 6

by 4

by 6

by 4

1 by 6

1 by 4

by 6

by 4

by 8

by 4

by 6

by 6

1 by 8

Iby 4

2 by 8

by 4

by 4

by 4

by 8

by 6

by 4

by 6

6 feet

In.

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

1 by

1 by

1 by

1 by

1 by

1 by

1 by

Iby

1 by

by

by

by

by 6

by 4

by 6

by 6

by 6

by

by

by

by

by

by

by

by 6

by 4

by 4

by 4

8 feet

In,

1 by 4

1 by 4

1 by 4

Iby 6

by

by

by

by

2 by 4

2 by 4

2 by 4

2 by 4

>2 by 4

2 by 4

^2 by 4

>2 by 4

by

by

by

by

by

by

by

by 6

by 6

by 4

by 4

by 6

10 feet

2 by 4

2 by 4

2 by 4

2 by

2 by

2 by

2 by

by

by

by

by 6

by 6

by 4

by 4

by 6

12 feet

In.

2 by 4

2 by

2 by

1 by

2 by

by

by

by

by 4

by 4

by 4

by 4

by 4

by

by

by

by

by

by

by

2 by 4

'2 by 4

2 by 4

by

by

by

by

by

by

by

by 6

by 4

by 4

by 4

by 6

by 6

by

by

by

by

by

by

by 6

^ With horizontal joist supports, except as indicated,

^ Crates require special design, . ,,,.-,

3 Crates require 2 by 4 vertical joist supports when struts are 1 mch thick.
92 AGRICULTURE HANDBOOK 2 5 2, U.S. DEPT. OF AGRICULTURE

TABLE 29.—Panel member sizes Jor crates^ designed Jor a net load oj 6,000 pounds

4-FOOT-WIDE CRATE

Length

Ft.

10

12

16

20

24

28

32

36

40

44

48

Member

Crate height

rUpper frame.

J Lower frameStrut

[Diagonal

iUpper frame.

Lower frame_

Strut

Diagonal

Upper frame.

Lower frame.

jStrut

[Diagonal

'Upper frame.

Lower frame.

Strut

Diagonal

[Upper frame..

J Lower frame..

iStrut

[Diagonal

[Upper frame..

J Lower frame..

[Strut

[Diagonal

[Upper frame..

I Lower frame..

Strut

[Diagonal

[Upper frame._

I Lower frame. _

Strut

[Diagonal

'Upper frame..

Lower frame. _

Strut

.Diagonal

Upper frame._

Lower frame. _

Strut

Diagonal

Upper frame..

Lower frame..

Strut

Diagonal..

Upper frame..

Lower frame..

Strut

Diagonal

Upper frame. _

Lower frame..

Strut

Diagonal

See footnotes at end of table.
WOOD CRATE DESIGN MAISTUAL 93

TABLE 29.—Panel member sizesjor crates ^ designedjor a net load oj6fi00 pounds—Continued

6-FOOT-WIDE CRATE

Length

Ft.

10

12

16

20

24

28

32

36

40

44

48

Member

Upper frame

Lower frame

Strut

Diagonal

Upper frame

Lower frame

Strut

Diagonal

Upper frame

Lower frame

Strut

Diagonal

Upper frame

Lower frame

Strut

.Diagonal

Upper frame

Lower frame

Strut

.Diagonal

Upper frame

Lower frame

Strut

.Diagonal

Upper frame.

Lower frame.

Strut

Diagonal

Upper frame.

Lower frame.

Strut

Diagonal

Upper frame.

Lower frame.

Strut

Diagonal

Upper frame.

Lower frame.

Strut

Diagonal

Upper frame.

Lower frame.

Strut

Diagonal

Upper frame.

Lower frame.

Strut

Diagonal

Upper frame.

Lower frame.

Strut

Diagonal

2 feet

In.

1 by 4

1 by 4

1 by 4

Iby

by

by

by

by

by

1 by

1

2

1

1

1

by

by

by

by

bye)

{')

(')

(')

(') e)

(') e)

{')

(')

(')

{')

{')

(')

(')

(')

{')

(')

(')

{')

{')

(')

{')

{')

(') e)e)

Crate height

4 feet

In.

1 by 4

1 by 4

Iby 4

4 by 4

1 by 4

by 6

by 4

by

by

by

by

by

bv

by

1 by

1 by

1 by

2 by 6

1 by 4

Iby 4

1 by 4

2 by 6

1 by 4

1 by 6

1 by 4

2 by 8

1 by 4

1 by 6

1 by 4

2 by 8

1 by 4

1 by 6

1 by 4

2 by 10

1 by 4

1 by 6

1 by 4

6 feet

In.

1 by 4

Iby 4

1 by 4

Iby 4

Iby 4

1 by

Iby

Iby

1 by

Iby

1 by

by

by

by 6

1

1

1

1

1

1

1

1

1

1

2

1

Iby 4

by

by

by

by

by

by

by

by

by 4

by 6

by 4

by 4

by 4

by 6

by 6

by 4

by 4

2 by 4

2 by 6

2 by 4

2 by 4

2 by 4

8 feet 10 feet

2 by 4

2 by 4

2 by 4

2 by 4

2 by 4

2 by 4

2 by 4

2 by 4

2 by 4

2 by 4

2 by 4

2 by 6

2 by 4

2 bv 4

2 by 4

1 by 4

1 by 4

1 by 4

Iby 4

fl by

Iby

1 by

1 by

1 by

1 by

Iby

1 by

1 by

1 by

1 by

1 by 6

ilby 4

by

by

by

by

by

by

Uby

2 by 4

2 by 4

2 by 6

2 by 4

2 by 4

2 by 4

n2feet

In.

1 by 4

by

by

by

by

by

by

by

by 6

by 4

by

by

1 by

1 by

1 by

by

by

by

by

by

by 6

2 by 4

2 by 4

2 by 4

2 by 4

2 by 4

by

by

by

by

by

by

by

by

See footnotes at end of table.
94 AGRICULTURE HANDBOOK 2 5 2, U.S. DEPT. OF AGRICULTURE

TABLE 29.—Panel member sizes for crates ^ designedfor a net load of 6fi00 pounds—Continued

8-FOOT-WIDE CRATE

Length Member

Crate height

2 feet 4 feet 6 feet 8 feet 210 feet 12 feet

Ft.

10

12

16

20

24

28

32

36

40

44

48

Upper frameLower frameStrut

Diagonal

Upper frame.

Lower frame.

Strut

Diagonal

Upper frame.

Lower frame_

jStrut

[Diagonal

I Upper frame.

Lower frame.

Strut

Diagonal

iUpper frame.

Lower frame.

Strut

Diagonal

I Upper frame.

Lower frame.

Strut

Diagonal

Upper frame.

J Lower frame.

Strut

[Diagonal

I Upper frameLower frame..

Strut

Diagonal

Upper frame.

Lower frame..

Strut

Diagonal

I Upper frame.

Lower frame.

Strut

Diagonal

I Upper frame..

Lower frame..

Strut

Diagonal

I Upper frame..

Lower frame..

Strut

Diagonal

Upper frame..

Lower frame..

Strut

[Diagonal

In.

a by 4

>l by 4

1 by 4

by

by

by

by

by

by

by

by

by

by

by

by

{')

{')

{')

{')

{')

{')

{')

(')

{')

{')

P)

{')

{')

{')

{')

{')

{')

{')

{')

{')

{')

0)

{')

{')

C)

{')

{')

{')

In.

1 by 4

1 by 4

1 by 4

a by 4

a by 4

1 by

1 by

1 by

Iby

2 by

1 by

by

by

by

by

by 6

by 4

by

by

by

by

by

by

by 6

by 4

by 8

by 4

by 6

by 6

by 8

1 by 4

by 6

by 6

by 10

by 6

by 6

by 6

In.

1 by 4

1 by 4

1 by 4

1 by 4

.1 by 6

1 by 4

1 by 4

1 by 4

1 by

Iby

1 by

1 by

1 by

1 by

1 by

1 by

1 by

1 by

1 by

1 by

•2 by 4

2 by

2 by

2 by

2 by

2 by

2 by

by

by

by

by

by

by

by 8

by 4

by 4

by 4

In.

Í1 by 4

Il by 4

1 by 4

[iby 6

^2 by 4

2 by 4

2 by 4

2 by

2 by

by

by

by

by

by

by

by

by

by

by

In.

1 by 4

1 by 4

1 by 4

2 by 4

2 by 4

2 by 4

2 by 4

by 6

by 4

by 4

by 4

by 6

by

by

by

by

by

by

by

See footnotes at end of table.

In.

2 by 4

2 by 4

2 by 4

2 by 4

Iby 6

2 by 4

2 by 4

2 by 4

1 by 6

2 by 4

by 4

by 4

bye

by 4

by 4

by 4

Iby 6

'2 by 4

2 by 4

2 by 4

2 by 4

2 by 4

2 by 4

2 by 6

by 4

by 4

by 4

by 6

by 4

by 4

2 by 4

2 by 6

by 6

by 4

by 4

by 6

by 6

by 4

by 4

by 6
WOOD CRATE DESIGN MATsTUAL

TABLE 29.—Panel member sizesfor crates^ designedfor a net load of 6,000 pounds—Continued

lO-FOOT-WIDE CRATE

95

Length

FL

10

12

16

20

24

28

32

36

40

44

48

Member

IUpper frame.

Lo\^ er frame.

Strut

Diagonal

iUpper frame.

Lo^\ er frame.

Strut

Diagonal

iUpper frame.

Lower frame.

Strut

Diagonal

iUpper frame.

Lo\\ er frame.

Strut

Diagonal

[Upper frame.

J Lower frame.

"Strut

Diagonal

Upper frame.

Lower frame.

Strut

^Diagonal

Upper frame.

Lo%\er frame.

Strut

.Diagonal

'Upper frame.

Lo^er frame.

Strut

.Diagonal

Upper frame.

Lower frame.

Strut

.Diagonal

Upper frame.

Lo\^ er frame.

Strut

.Diagonal

'Upper frame.

Lower frame _

Strut

.Diagonal

Upper frame..

Lower frame_.

Strut

.Diagonal

Upper frame..

Lower frame..

Strut

.Diagonal

2 feet

4 by 4

by 4

Iby 4

by 4

by 4

0)

(')

(')

(')

(')

(')

{')

{')

p)

(2)

(')

{')

(')

{')

0)

(')

0)

{')

In.

Iby 4

1 by 4

Iby 4

a by 4

Crate height

4 feet 6 feet 8 feet

In.

1 by 4

Iby 6

^2by 4

2 by 4

bye

by 4

by 4

by 4

bv 6

by 4

by 4

bv4

by 6

by 4

by 4

by 4

by 8

by 4

by 4

by 4

In.

2 by 4

2 by 4

2 by 4

2 by 4

2 by 4

2 by 4

2 by 4

2 by 4

by

by

by

bv

by

by

by

by

by

by

by 4

by 6

by 6

by 4

by 4

by 6

by 8

by 4

by 4

by 6

10 feet

Iby 4

2 by 4

'2 by 4

2 by 4

2 by 4

Iby 6

2 by 4

2 by 4

by 4

by 4

by 4

bye

by

by

by

by

2 by

2 by

by

bv 6

bye

by 4

by

by

by

by

bv

by

12 feet

In.

2 by 4

2 by 4

2 by 4

Iby 4

2 by 4

2 by 4

'2 by 4

^2 by 4

2 by 4

2 by 4

2 by 4

2 by 4

2 by 4

bye

by

bv

by

by

by

by

by

by

by

by

by

by

bye

by 4

by 4

bye

bye

by 4

by 4

bye

^ With horizontal joist supports, except as indicated.

^ Crates require special design.

* Crates require 2 by 4 vertical joist supports when struts are 1 inch thick.

692-318 0—64-
96 AGRICULTURE HANDBOOK 2 5 2, U.S. DEPT. OF AGRICULTURE

TABLE 30.—Panel member sizes for crates ^ designed jor a net load oj SflOO founds

4-FOOT-WIDE CRATE

Length

Ft.

10

12

16

20

24

28

32

36

40

44

48

Member

Upper frame.

Lower frame.

Strut

Diagonal

Upper frame.

Lower frame.

Strut

[Diagonal

I Upper frame.

Lower frame.

Strut

Diagonal

I Upper frame.

Lower frame.

Strut

Diagonal

rUpper frame..

I Lower frame..

Strut

Diagonal

Upper frame..

Lower frame..

Strut

Diagonal

Upper frame..

Lower frame..

Strut

Diagonal

Upper frame..

Lower frame..

Strut

Diagonal

Upper frame. _

Lower frame. _

Strut

Diagonal

Upper frame..

Lower frame..

Strut

[Diagonal

Í Upper frame. _

j Lower frame._

Strut

[Diagonal

Upper frame. _

Lower frame..

Strut

Diagonal

Upper frame..

Lower frame..

Strut

Diagonal

Crate height

2 feet

In.

1 by 4

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by 8

bv 4

by 4

by 4

\')

{')

{')

{')

{')

{')

{')

{')

(')

{')

{')

{')

(')

(')

{')

{')

{')

(2)

(2)

(2)

(2)

(')

{')

{')

(')

{')

(')

(')

4 feet

In.

1 by 4

[l by 4

1 by 4

n by 4

a by 4

1 bv 6

1 bv 4

1 b> 4

1 by 4

2 by 6

bv 4

by 4

by

bv

by

1 by

by

bv

bv

1 by

by

by 8

by 4

bv 4

bv 6

bV 8

by 4

by 4

by 6

by 8

1 by

by 4

1 bv 6

2 by 10

1 by 6

1 by 4

1 by 6

6 feet

1 by 4

See footnotes at end of table.

2 by 4

8 feet

2 by 4

^2 by 4

\2 by 4

2 by 6

2 by 4

2 by 4

2 by 4

10 feet

In.

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

1 by 4

.Iby 6

1 by 4

1 by 4

1 by 4

1 by 6

4

4

4

6

4

4

6

1 by

1 by

1 by

1 by

1 by

1 by

1 by

.1 by 6

2 by 4

2 by 4

2 by 4

2 by 4

by 6

by 4

by 4

by 4

12 feet

2 by 4

Iby 6

2 by 4

2 by 4

2 by 4

2 by 4

2 by 4

2 by 4

2 by 6

2 by 4

2 by 4

2bv4
WOOD CRATE DESIGN MANUAL 97

TABLE 30.—Panel member sizes for crates ^ designed for a net load of 8,000 pounds—Continued

6-FOOT-WIDE CRATE

Length Member

Crate height

2 feet 4 feet 6 feet 8 feet 10 feet 312 feet

Ft.

10

12

16

20

24

28

32

36

40

44

48

IUpper frame-.

Lower frame..

Strut

Diagonal

Upper frame..

Lower frameStrut

Diagonal

Upper frameLower frameStrut

Diagonal

Upper frameLower frameStrut

Diagonal

Upper frameLower frameStrut

Diagonal

Upper frameLower frameStrut

^Diagonal

IUpper frameLower frameStrut

Diagonal

Upper frameLower frameStrut

Diagonal

Upper frameLower frameStrut

Diagonal

Upper frameLower frameStrut

Diagonal

Upper frameLower frameStrut

Diagonal

Upper frameLower frameStrut

Diagonal

Upper frame.

Lower frameStrut

.Diagonal

In.

1 by 4

by 6

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by 8

by 4

by 4

by 4

{')

{')

{')

{')

{')

(')

{')

{')

(')

(')

{')

{')

{')

(')

{')

(')

{')

{')

{')

{')

{')

(') m

{')

{')

In.

1 by 4

1 by 4

1 by 4

1 by 4

6

4

4

4

6

4

4

4

6

4

4

by

by

by

by

by

by

by

by

by

by

by

by 6

by 6

by 4

by 4

by 6

by 8

by 4

by 4

by 6

by 8

by 4

by 6

by 6

by 10

by 4

by 6

by 6

by 10

by 4

by 6

by 6

by 10

by 4

by 6

by 6

In.

by 4

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by 6

by

by

by

by

by

by

by

by

^2 by 4

2 by 6

2 by 4

2 by 4

2 by 4

\2 by 4

by

by

by

by

by

by

by

by

by 8

by 4

by 4

by 4

In.

2 by 4

2 by 4

2 by 4

2 by 4

2 by 4

i2 by 4

2 by 4

2 by 6

2 by 4

2 by 4

2 by 6

2 by 6

2 by 4

2 by 4

2 by 6

2 by 8

2 by 4

2 by 4

2 by 6

Iby 4

1 by 4

Iby

by

by

by

by

by

by

1 by 6

1 by 4

1 by 4

1 by 6

1 by 6

2 by 4

2 by 4

2 by 4

by 4

by 4

by 4

by 6

by 6

by 4

by 4

by 4

by 6

by 4

by 4

by 4

bye

by 4

by 4

b>6

In.

1 by 4

Iby 4

1 by 4

1 by 6

2 by 4

1 by

1 by

1 by

.Iby

-2 by 4

2 by 4

1 by 6

1 by 4

1 by 6

1 by 6

2 by 4

[2 by

I 2 by

,2 by

[2 by

2 by 4

2 by

2 by

2 by

2 by

2 by

2 by

2 by

2 by

by

by

by 4

by 6

by 6

by 4

by 4

by 6

4

4

4

6

4

4

4

6

4

4

See footnotes at end of taWe.
98 AGRICULTURE HANDBOOK 2 5 2, U.S. DEPT. OF AGRICULTURE

TABLE 30.—Panel member sizes for crates ^ designed for a net load of 8,000 pounds—Continued

8-FOOT-WIDE CRATE

Length

FL

10

12

16

20

24

28

32

36

40

44

48

Member

Upper frameLower frame.

Strut

Diagonal

Upper frameLower frame.

Strut

Diagonal

Upper frame.

Lower frameStrut

Diagonal

Upper frameLower frame.

Strut

Diagonal

'Upper frame.

Lower frame.

"iStrut

[Diagonal

I Upper frame..

Lower frame..

Strut

Diagonal

I Upper frame..

Lower frame..

Strut

Diagonal

Upper frame..

Lower frame..

IStrut

[Diagonal

I Upper frame..

Lower frame..

Strut

Diagonal

I Upper frame. _

Lower frame..

Strut

Diagonal

[Upper frame..

J Lower frame..

Strut

[Diagonal

Upper frame..

Lower frame..

Strut

[Diagonal

Upper frame. _

Lower frame..

1 Strut

[Diagonal

See footnotes at end of table.
WOOD CRATE DESIGN MANUAL 99

TABLE 30.—Panel member sizesfor crates^ designedfor a net load of 8,000 pounds—Continued

lO-FOOT-WIDE CRATE

Length Member

Crate height

2 feet 4 feet 6 feet 8 feet 10 feet 12 feet

FL

10

12

16

20

24

28

32

36

40

44

48

Upper frame.

Lower frame.

Strut

.Diagonal

fUpper frame.

Lower frame.

Strut

L Diagonal-_--

Upper frame.

Lower frame.

Strut___

[Diagonal-_--

[Upper frame.

I Lower frame.

|Strut_-.

[Diagonal

fUpper frame.

I Lower frame.

I Strut

[Diagonal

[Upper frame.

I Lower frame.

I Strut

[Diagonal

[Upper frame.

I Lower frame.

Strut

[Diagonal

[Upper frame.

I Lower frame.

Strut

[Diagonal-_--

[Upper frame.

I Lower frame.

I Strut

[Diagonal

[Upper frame.

I Lower frame.

Strut

[Diagonal

[Upper frame.

I Lower frame.

Strut

[Diagonal

[Upper frame.

I Lower frame.

Strut

[Diagonal

[Upper frame.

I Lower frame.

Strut

[Diagonal

In.

a bv 4

by 6

by

by

by

by

by

by

by

by 6

by

by

by

by

by

bv

by

by 8

by 4

by 4

by 4

(2)

e)

{')

{')

{')

(2)

(2)

(2)

{')

(')

(')

{')

0)

(2)

{')

{')

{')

(2)

(2)

{')

m

{')

{')

(2)

In.

1 by 4

a by 4

a by 4

a by 4

1 by

1 by

Iby

1 by

2 by

1 by

1 by

1 by

2 by

by

by

by 6

by 6

by 4

by 6

bye

by 8

by 4

1 by 6

1 by 6

2 by 8

4

4

6

10

4

4

4

2 by

2 by

1 by

2 by

2 by

2 by

2 by

2 by 10

2 by 4

2 by 4

2 by 4

2 by 12

2 by 6

2 by 4

2 by 4

2 by 4

1 by

^2 by 4

^2 by 4

by 6

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

2 by 8

4

4

6

10

4

4

6

^ With horizontal joist supports, except as indicated.

2 Crates require special design.

^ Crates require 2 by 4 vertical joist supports when struts are 1 inch thick.

In.

•2 by 4

2 by 4

2 by 4

^2 by 4

>2 by 4

2 by 4

'2 by 4

2 by 4

2 by 4

.2 by 6

2 by 6

2 by 4

2 by 4

2 by 6

2 by 6

by

by

by

by

by

by

by

by 6

by 4

by 4

by 6

by 8

by 4

by 4

by 6

by 8

by 4

by 4

by 6

In.

2 by 4

2 by 4

2 by 4

Iby 6

2 by 4

2 by

by

by

by

by

by

by

2 by 4

2 by 4

2 by 4

2 by 4

2 by 4

2 by 4

2 by 6

2 by 4

2 by

2 by

2 by

2 by

2 by

2 by

by

by 6

by 4

by 4

by 6

by 6

by 4

2 by 4

2 by 6

2 by 6

2 by 4

2 by 4

2 by 6

2 by 8

2 by 4

2 by 4

2 by 6

In.

2 by 4

2 by 4

2 by 4

2 by 4

2 by 4

'2 by

2 by

2 by

.2 by

2 by

2 by

2 by

2 by 6

2 by 4

2 by 4

2 by 4

2 by 6

by

by

by

by

by

2 by

2 by

2 by

by

by

by

by

by

2 by

2 by

2 by 8

2 by 8

2 by 4

2 by 4

2 by 8
100 AGRICULTURE HANDBOOK 2 5 2, U.S. DEPT. OF AGRICULTURE

TABLE 31.—Panel member sizes Jor crates^ designed Jor a net load oj lOfiOO pounds

4-FOOT-WIDE CRATE

Length Member

Crate height

2 feet 4 feet 6 feet 8 feet 10 feet 12 feet

Ft.

10

12

16

20

24

28

32

36

40

44

48

¡Upper frame.

Lower frame.

Strut

Diagonal

[Upper frame.

I Lower frame.

Strut

[Diagonal

I Upper frameLower frameStrut

Diagonal

¡Upper frameLower frameStrut

Diagonal

I Upper frameLower frame.

Strut

Diagonal

r Upper frame.

I Lower frame.

Strut

[Diagonal

Upper frame.

Lower frame.

Strut

.Diagonal

Upper frame.

Lower frameStrut

Diagonal

Upper frame.,

Lower frameStrut

Diagonal

Upper frame..

Lower frame-.

Strut

Diagonal

Upper frame..

Lower frame..

Strut

Diagonal

I Upper frame..

Lower frameStrut

Diagonal

(Upper frame..

Lower frameStrut

Diagonal

In.

1 by 4

by

by

by

by

bv

by

by

by

by

by

bv

by

by S

bv 4

by 4

by 6

bv 10

by 6

bv 4

bv 6

>)

{')

(')

P)

(2)

{')

(')

(')

(')

(')

(2)

(')

(')

(')

{')

P)

{') e)

{')

(')

(')

p)

(')

(')

(2)

{')

In.

1 bv 4

by

bv

by

by

by

bv

by

by

by

bv

1 bv

1 bv

1 bv

1 bV

1 bv

1 bv 6

2 bv 4

bv 4

bv 4

by 6

by 6

by

1 bv

1 by

2bv

1 bv

1 bv

bv 6

bV S

bV

bv

by

bv

bV

bV

by

bv 10

bV 6

bV 6

bV 6

by 10

by 4

bv 4

by 4.

by 12

by 6

by 4

by 4

In.

Í1 by 4

Il by 4

1 bv 4

^1 by 6

Í2 bv 4

^2 bv 4

^2 bv 4

•2 bv 4

In.

2 by 4

2 by 4

2 bv 4

2 bv 4

2 by 4

2 bv 4

bv 6

bv 4

bv 4

by 6

by 6

by 4

bv 4

2 bv 4

2 bv 6

2 bv 4

2 by

2 by

2b'y

2 by

2 by

2 by

2 by 8

2 by 4

2 by 4

2 by 6

1 by

2 by 4

2 bv 4

by 4

•2 by 4

2bv 6

2 by 4

2bv

2 by

by

by

by

by

by

by

by

2 by

In.

•2 by 4

2 by 4

2 by 4

2 by 4

2 by 4

2 by 4

2 by 4

2 by 4

2 by 4

2 by 4

2 by 4

.2 by 6

2 by 4

•2 by 4

2 by 4

2 by 4

2 by 4

2 by 6

2 by 6

2 by 4

2 by 4

2 by 6

See footnotes at end of table.
WOOD CRATE DESIGN MANUAL 101

TABLE 31.—Panel member sizesjor crates ^ designed jor a net load oj 10,000 pounds—Continued

6-FOOT-WIDE CRATE

Length

Ft.

Member

10

12

16

20

24

28

32

36

40

44

48

[Upper frame,

I Lower frame.

Strut

[Diagonal

¡Upper frame_

Lower frame.

Strut

Diagonal

CUpper frameLower frame.

Strut

[Diagonal

(Upper frameI Lower frame.

Strut

[Diagonal

IUpper frame.

Lower frame.

Strut

Diagonal

IUpper frame.

Lower frame _

Strut

Diagonal

IUpper frame.

Lower frame.

Strut

Diagonal

ILTpper frame.

Lower frame.

Strut

Diagonal

IUpper frame.

Lower frame.

Strut

Diagonal

iUpper frame.

Lower frame.

Strut

Diagonal

I Upper frame.

Lower frame.

Strut

Diagonal

[Upper frame.

I Lower frame.

Strut

[Diagonal

IUpper frame.

Lower frame.

Strut

Diagonal

Crate height

2 feet

In.

1 bv 4

4

6

6

4

4

6

6

4

4

6

bv 6

bv 4

by

bv

by

by

by

by

by

by

by

by

by 8

by 4

by 4

by 6

by 10

bv 6

by 4

by 6

K')

(')

{')

K')

C)

{')

(')

(')

{')

{')

{')

0)

{')

{')

{')

C)

{')

{')

{')

{')

«

4 feet

In.

Iby 4

1 by

1 by

Iby

1 by

Iby

1 by

Iby

1 by

1 by

1 bv

1 by

1 by

1 by

1 by

1 bv

1 by

2 by

Iby

Iby

Iby

2 by

Iby

1 bv

1 by

2bv

1 by

1 by

1 by

2 by 8

Iby 4

1 by 6

1 by 6

2 by 8

2 by 4

2 by 4

2 by 4

2 by 10

2 by 4

2b> 4

2 by 4

2bv 12

2 by 4

2 by 4

2 by 4

2 by 12

2 by 6

2 by 4

2 by 4

4

4

4

6

4

4

4

6

4

4

4

6

6

4

4

6

6

4

4

6

6

4

6

6

6

4

4

6

6 feet

In

Iby 4

Iby 4

1 by 6

Iby 6

2 bv 4

Iby

1 by

Iby

Iby

2 by 4

^2bv 4

^2 by 4

2 by 6

2 by 4

2 bv

by

by

by

by

by

by

by

by

by

by 8

bv 4

2 by 4

2 bv 4

2 by 8

2 by 4

2 by 4

2 by 4

2 by 8

2bv 4

2 by 4

2 by 6

2 by 10

2 bv 4

2 by 4

2 by 6

8 feet

In.

2 by 4

2 by 4

2 by

2 by

2 by

2 by

2 by 4

2 by 4

2 by 4

2 by

2 by

by

by

by

by

by

by

2 by

2bv

2 by

2 by

2 by 6

2 by 4

2 by

2 by

bv

by

by

hy

by 8

by 4

by 4

2 by 6

2 by 8

2 by 4

2 by 4

2 by 6

10 feet

by 6

2bv 4

by 4

by 4

2 by

2 by

2 by

2 by

2 by

2 by

2b3

2 by 6

2 by

2 by

2 by

2 by

2 by

by

by

by

by

by

by

2

2

2

2

2

2

2bv 6

2 by 6

2 by

2 by

2 by

2 by

2 by

2 by

by 6

312 feet

In.

^2 by 4

^2 by 4

^2 by 4

2 by 4

2 by 4

2 by 4

by

by

by

by

by

by

by

by

by

by

by

2 by

2 by

2 by

2 bv

2 by

2bv

2 by

2 by 4

2 by 6

2 by 6

2 by 4

2 by 4

2bv 6

2 by 6

2 by 4

2 by 4

2 by 6

See footnotes at end of table.
102 AGRICULTURE HANDBOOK 2 5 2, U.S. DEPT. OF AGRICULTURE

TABLE 31.—Panel member sizes Jor crates ^ designedjor a net load of 10,000 pounds—Continued

8-FOOT-WIDE CRATE

Length

Ft.

6

10

12

16

20

24

28

32

36

40

44

48

Member

Upper frame_

Lower frame.

Strut

Diagonal

Upper frame_

Lower frame_

Strut

Diagonal

Upper frameLower frame.

Strut

.Diagonal

Upper frameLower frame.

Strut

Diagonal

Upper frameLower frameStrut

Diagonal

rUpper frame-.

J Lower frame-.

jStrut

[Diagonal

ÍUpper frame,.

J Lower frame..

Strut

^Diagonal

IUpper frame..

Lower frame-.

Strut

Diagonal

fUpper frame..

J Lower frame..

iStrut

[Diagonal

!Upper frame--

Lower frame. _

Strut

Diagonal

rUpper frame._

j Lower frame..

Strut

[Diagonal

! Upper frame..

Lower frame..

Strut

Diagonal

(Upper frame._

Lower frame..

Strut

Diagonal

Crate height

2 feet

In.

1 by 4

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

See footnotes at end of table.

by 10

by 6

bv 4

by 6

(')

(')

(')

(')

(')

{')

(')

(')

(')

(')

(')

{')

(')

(')

(')

(')

(')

(2)

(2)

(')

(')

(')

(')

{')

(')

(')

(')

4 feet

In.

fl by 4

1 bv 4

1 by 6

1 bv 4

1 by 4

1 by 4

1 by 6

1 by 6

1 by 4

1 by 4

1 by 4

1 by 6

1 by 4

1 by 4

1 by 4

1 by 6

1 by 6

1 by 4

1 by 6

1 by 6

2 by 6

1 by 4

1 bV 4

1 by 6

2 bv 6

1 by 4

1 by 6

1 by 6

2 bv 8

2 by 4

2 by 4

2 by 4

2 bV

by

10

4

10

4

2 by 4

2 by 4

2 b\

2 by

2 bv 4

2 by 4

2 by 12

2 by 4

2 bv 4

2 by 4

2 bv 12

2 by 6

2 by 4

2 bV 6

2 by 12

2 by 6

2 by 4

2 by 4

6 feet

In.

2 by 4

2 by 4

1 by 4

1 by 4

1 by 6

1 by 6

2 by 4

•2 by 4

2 by 4

by

by

by

bv

by 6

by

bv

by

by

by

by

by

by 8

bV 4

by 4

by 4

by 8

by 4

by

by

bv

b>

bv

bV

by

by

by

4

4

8

4

4

6

10

4

4

8 feet

In.

2 by 4

2 by 4

2 by 4

2 by 4

2 by 4

2 by 6

by 6

by

bV

bV

by

by

bv

bV

bV 6

bv 4

by 4

bv 4

by 6

by 6

by

by

by

by

by

by

bv

by

by

by

by

by

by

by

by

bv

bV

bV

by

by

by

by

by

310 feet

2 by 4 2 by 4

2 by 4

2 bv 4

by

by

by

by

by

by

by

by

by

by

by

by

by

by

bv

bV

by

by

by

by

by

by

by

by

12 feet

In.

2 by 4

2 by 4

2 by 4

2 by 4

2 by 4

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by 6

by 6

by 4

by 6

by 6
WOOD CRATE DESIGN MANUAL 103

TABLE 31.—Panel member sizesfor crates ^ designed for a net load oj lOfiOO pounds—Continued

10-FOOT-WIDE CRATE

Length Member

Crate height

2 feet 4 feet 6 feet 8 feet 10 feet 12 feet

Ft.

10

12

16

20

24

28

32

36

40

44

48

IUpper frame __

Lower frame. _

Strut

Diagonal

IUpper frame.-

Lower frame..

Strut

Diagonal

IUpper frame..

Lower frame..

Strut

Diagonal

IUpper frame..

Lower frame..

Strut

Diagonal

1Upper frame..

Lower frame..

Strut

Diagonal

1Upper frame.

Lower frameStrut

Diagonal

IUpper frame.

Lower frame.

Strut

Diagonal

Upper frame.

Lower frame.

Strut

Diagonal

IUpper frame.

Lower frame.

Strut

Diagonal

I Upper frame.

Lower frame.

Strut

Diagonal

I Upper frame.

Lower frame.

Strut

Diagonal

1 Upper frame.

Lower frame.

Strut

Diagonal

I Upper frame.

Lower frameStrut

Diagonal

In.

1 by 4

1 by

1 bV

1 by

1 bv

1 by

1 bv

1 by

1 by 6

2bv 6

1 by 4

1 by 4

1 bv 6

2 by 8

1 by 4

1 by 4

1 bv 6

2bv 10

1 by 6

by 4

by 6

e)

{')

{')

{')

{')

{')

{')

(')

(')

{')

{')

(')

{')

{')

(')

{') e)

{')

{')

{')

{')

{')

{')

{')

(')

In.

1 bv 4

1 by

1 by

Iby

1 by

1 by

1 by

1 by

1 by

1 by

1 bv

1 by

1 bv

1 bv

1 by

1 by

1 bv

1 by

1 by

1 bv

2 by

by

by

by

bv 8

bv 4

by

by

2 bv

2bv

2 by

2bv

2 by

2 by

2bv

2bV

b'y

by

by

by

4

4

8

4

4

4

10

4

4

4

10

4

4

4

by 12

bv 6

by 4

by 4

by 12

by 6

by 4

by 6

by 12

by 8

by 4

by 4

In.

2 by 4

2 by 4

2 by 4

2 by 4

2 by 4

2 by 4

by

by

by

by

by

by

by

by

by

by 4

by 4

2bv 6

2 by 8

by 4

by 4

by 6

bv 8

bv 4

bv 4

bV 6

bv 10

bV 4

by 4

by 6

2 by 10

2 by 4

2 bv 4

2 bv 6

In.

2 by 4

2 bv 4

2 by 4

In.

2 by 4

'2 bv 4

2 by 4

2 by 4

2 by 4

2 by 4

by 6

by 4

by

by

by

2 by

2bv

2 by

2 by

2 by

2 by

by

by 6

by 4

b>4

by 4

bv 6

by 6

by 4

bV 4

2 by 6

2bv 6

by 4

by 4

bv 6

bv 6

by 4

by 4

bV 6

bv 8

bv 4

bv 4

by 6

4

4

6

4

4

4

6

4

4

4

In.

2 by 4

2 by 4

2 by 4

2 by 4

2bV6

2 by 4

2 by 4

^2 by 4

2 by 4

2 by 4

2 by 6

2 by 6

" 4

4

6

6

4

4

4

6

4

4

4

6

6

4

4

2 by

2 by

2 bv

2 by

2 by

2 by

2bV

2 bv

2 by

2 by

2 by

2bV

by

by

by

by 6

by 6

bv

by

by

bv

by

by

bv 8

by 8

2 by 4

2 by 6

2 by 8

4

4

6

6

4

4

^ With horizontal joist supports, except as indicated.

2 Crates require special design. u +u-^i^

3 Crates require 2 by 4 vertical joist supports when struts are 1 men tnicK.
104 AGRICULTURE HANDBOOK 2 5 2, U.S. DEPT. OF AGRICULTURE

TABLE 32.^Panel memher sizes jor crates^ designed jor a net load oj 15,000 pounds

4-FOOT-WIDE CRATE

Length

Ft

12

16

20

24

28

32

Upper frameLower frameStrut

Diagonal

Upper frame.

Lower frame.

Strut

Diagonal

Upper frame.

Lower frame.

Strut

Diagonal

Upper frame.

Lower frame.

Strut

Diagonal

Upper frameLower frame.

Strut

Diagonal

^Upper frame.

Lower frame.

Strut

[Diagonal

Upper frame.

I Lower frame.

I Strut

[Diagonal

fUpper frame.

I Low^er frame.

iStrut

[Diagonal

ÍUpper frame.

I Lower frame _

Strut

[Diagonal

Member

Crate height

See footnotes at end of table.
WOOD CRATE DESIGN MANUAL 105

TABLE 32.—Panel member sizesjor crates^ designed jor a net load oj 15,000 pounds—Continned

6-FOOT-WIDE CRATE

Length

Ft.

10

12

16

20

24

28

32

Member

Crate height

Upper frame

Lower frame

Strut

Diagonal

IUpper frame

Lower frame

Strut

Diagonal

IUpper frame

Lower frame

Strut

Diagonal

IUpper-frame

Lower frame

Strut

Diagonal

I Upper frame

Lower frame

Strut

Diagonal

I Upper frame

Lower frame

Strut

Diagonal

¡Upper frame

Lower frame

Strut

Diagonal

IUpper frame

Lower frame

Strut

Diagonal

IUpper frame

Lower frame

Strut

Diagonal

4 feet

In.

2 by 4

2 by 4

2 by 4

2 by 4

2 by 4

2 by 6

2 by 4

2 by 4

2 by 6

2 by 6 3

2 by 4

2 by

2 by

2 by

2 by

by 6

6 feet

In.

2 by 4

by 4

2 by

2 by

2 by

2 by

2 by

2 by

2 by

2 by

2 by 6

2 by

2 by

2 by

2 by

2 by

2 by

2 by

4

4

6

62

4

4

6

8 feet

In.

r2by 4

2 by 4

2bv 4

.2 by 42

2 by 4

2 by 4

2 by

2 by

2 by

2 by

2 by

2 by 6

2 by

2 by

2bv

2 by

2 by

2 by

2 by 6

2 by 6

2 by

2 by

2 by

2 by

2 by

2 by

2 by

by

by

by

by 42

by 6

2 by 6 2

2 by 4

2 by 42

2 by 6

10 feet

In.

2 by

2 by

2 by

2 by

2 by

2 by

2 by

2 by

2 by

2 by

2 by

by

by

by

by

by

by

by

2 by 6

2 by 6

2 by

2bv

2bV

2 by

2 by

2 by

by

4

4

4

6

4

4

42

4

4

4

6

6

4

4

6

6

4

4

by 6

by

by

by

by

2 by

2 by

2 by

2 by

12 feet

In.

2 by 4

2 by 4

2 by 4

2 by 6

2 by 4

2 by 4

2 by 6

2 by 6

2 by

2 by

2 by

2 by

2 by

2 by

2 by

2 by

2 by

2 by

2 by 6

2 by 6

2 by

2 by

2 by

2 by

2 by

2 by

2 by

2 by

2 by

by

by

by

by

by

by

by

See footnotes at end of table.
106 AGRICULTURE HANDBOOK 2 5 2, U.S. DEPT. OF AGRICULTURE

TABLE 32.~-Panel member sizesfor crates ' designedJor a net load of 15,000 pounds—Continued

8-rOOT-WIDE CRATE

Length

FL

12

16

20

24

32

Upper frame

Lower frame

Strut

Diagonal

'Upper frame

Lower frame

.Strut

[Diagonal

[Upper frame

I Lower frame

Strut

[Diagonal

I Upper frame

Lower frame

Strut

Diagonal

IUpper frame

Lower frame

Strut

Diagonal

IUpper frame

Lower frame

Strut

Diagonal

IUpper frame

Lower frame

Strut

Diagonal

IUpper frame

Lower frame

Strut

Diagonal

IUpper frame

Lower frame

Strut

Diagonal

2 by

2 by

2 by

2 by

2 by

2 by 6

2 by 6

2 by 4

2 by 4

2 by 6

2 by 6

2 by 4

2 by 4

2 by 4

2 by 6

2 by 42

2 by 4

2 by 4

2 by 8

See footnotes at end of table.
WOOD CRATE DESIGN MANUAL 107

TABLE 32.—Panel member sizesfor crates ^ designed for a net load of 15,000 pounds—Continued

10-FOOT-WIDE CRATE

Length Member

Crate height

4 feet 6 feet 8 feet 10 feet 12 feet

Ft,

10

12

16

20

24

28

32

Upper frame

Lower frame

Strut

Diagonal

Upper frame

Lower frame

Strut

^ Diagonal

'Upper frame

Lower frame

Strut

.Diagonal

'Upper frame

Lower frame

Strut

, Diagonal

Upper frame

I Lower frame

[Strut

[Diagonal

Í Upper frame

I Lower frame

I Strut

[Diagonal

[Upper frame

I Lower frame

I Strut

[Diagonal

[Upper frame

I Lower frame

[Strut

[Diagonal

[Upper frame

I Lower frame

[Strut

[Diagonal

In.

2 by 4

2 by 4

2 by 4

by 4

by 4

by 4

by 42

by 6

by

by

by

by

by

by

by 6

by 6 3

by 4

by 4

by 6

by 8 2

by 4

by 4

bv6

by 8 3

by 42

by 42

by 6

by 42

by 6

In.

by 4

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by 6

by 4

bv4

by 6

by 6

bv 4

by 4

by 4

by 6

by 6

by

by

by

by

by

by 42

by 6

by 6 2

bv 4

by 42

by 8

In.

2 by 4

2 by 4

2 by 6

2 bv 6

by 4

by 4

by 6

by 42

by 4

by 4

by 6

by 6

by 4

by

by

by

by

by

by

by

by

by

by

by

by 6

by

by

by

by

by

by

by

by

by

by

by 8

In.

by 4

by

by

by

by

by

by 6

by 6

by 4

by 4

by 6

by 6

by

by

by

by

by

bv

by

by

by

by

by

by

by 6

by 4

by

by

by

bv

bV

by 8

by 6

by 4

by 4

bv8

^ Sizes are for uniform loads but apply also to concentrated loads except as indicated.

2 For concentrated loads, increase the member size to the next larger size, as a 2 by 4 to a 2 by 6.

3 For concentrated loads, increase the member size to the second larger size, as a 2 by 6 to a 2 by 10.
108 AGRICULTURE HANDBOOK 2 5 2, U.S. DEPT. OF AGRICULTURE

TABLE 33.—Panel member sizes for crates^ designed for a net load oj 20fl00 pounds

4-FOOT-WIDE CRATE

Length

Ft.

10

12

16

20

24

28

32

Member

r Upper frame

I Lower frame

Strut

[Diagonal

[Upper frame

I Lower frame

Strut

[Diagonal

I Upper frame

Lower frame

Strut

Diagonal

[Upper frame

I Lower frame

Strut

[Diagonal

Í Upper frame

I Lower frame

Strut

[Diagonal

r Upper frame

I Lower frame

Strut

[Diagonal

I Upper frame

Lower frame

Strut

Diagonal

¡Upper frame

Lower frame

Strut

Diagonal

¡Upper frame

Lower frame

Strut

Diagonal

4 feet

In.

by 4

by 4

by 6

by 6

by 42

by 4

by 6

by 6

by 6

by 4

by

by

by

by

by

by

by

by

by

by

by

by

bv

by

by 8

by 4

by 4

bV 6

bV S

by

by

by

by

by

by

by

4

4

6

10 4

4 4

44

6^

Crate height

6 feet

In.

by 4

by 4

by 6

by 6

by 4 •

by 4

by 6

bv 6

by 6

by 4

2 by 6

2 by 6

by 6

by

by

by

by

by

by

by

by

2 by

2 by

2 by

2 by 6 2

2 by 4

2 by 42

by 6

by 6

by

by

by

2 by

2 by

2 by

2 by

8 feet

In.

by

by

by

by

by

2 by

2 by

2 by 6

2 by 6

by 4

by 6

by 8

by 6

by

2 by

2 by

2 by

2 by

by 6

bV 6

b>6

by

by

by

by

by

by

2 by 8

2 by 6 2

by 4

by 42

by 0

by 6 2

by 4

by 42

by 8

10 feet 12 feet

In.

by

by

by

by

by

by

by

by

by

by

by

by

by

by 4

by 6

by 6

by 6

by

by

by

by

by

by

by

by

by

by 6

2 by

2 by

by

by

by

by

by

by

by 6

In.

by 4

by 4

by 6

by 6

by 4

by 4

by 6

by 6 2

by

by

by

by

by

by 4

by 6

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by 6 2

See footnotes at end of table.
WOOD CRATE DESIGN MAJSTUAL 109

TABLE 33.—Panel memher sizes for crates^ designed for a net load of SO,000 pounds—Continued

6-FOOT-WIDE CRATE

Length Member

Crate height

4 feet 6 feet 8 feet 10 feet 12 feet

Ft.

10

12

16

20

24

28

32

Upper frame.

Lower frame.

Strut

Diagonal

Upper frame.

Lower frame.

Strut

Diagonal

LTpper frame.

Lower frame.

Strut

^ Diagonal

'Upper frame

Lower frame

Strut

t Diagonal

Upper frame

I Lower frame

iStrut

[Diagonal

fUpper frame

I Lower frame

I Strut

[Diagonal

r Upper frame

I Lower frame

IStrut

[Diagonal

[Upper frame

I Lower frame

IStrut

[Diagonal

[Upper frame

I Lower frame

Strut

[Diagonal

In.

by 4

by 4

by 6

by 6

by 4 '

by 4

by 6

by 6

by 6

by 4

by 4

bV 6

bV 6

by 4

by 4

by 6

by 6

by

by

by

by

by

by

by 6

by 8 3

by 42

by 42

by 6

by 8 3

by 42

by 4

by "

by

by

by

by

10^

44

44

6^

In.

2 by

2 by

2 by

2 by

2 by

2 by

2 by

2 by

2 by

2 by

2 by 6

2 by 6

2 by 6

2 by 4

2 by 6

2 by 6

2 by 6

2 by 4

2 by 4

by 6

by 6

by 4

by 4

by 6

by 6

by

by

by

by

by

by

2 by

2 by

2 by

2 by

2 by 6

In.

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by 6

2 by

2 by

2 by

by

by

by

by

by 6

by 6

2 by

2 by

2 by

2 by

2 by

2 by

by

by 6 2

by 4

by 42

by 8

In.

by 4

by 4

by 6

by 6

by

by

by

2 by

2 bV

2 by

2 by 6

by

by

by

by

by

by

by

by

by

by

by

by 6

by 6

by 6

by 4

by 6

2 by 8

2 by 6

2 by 4

2 by 4

2 by 8

2 by 6

2 by 4

2 by 4

2 by 8

In.

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by 6

by 6

by 6

2 by 4

2 by 6

by 6

b>6

by

by

by

by

by

by

by 8

See footnotes at end of table.
no AGRICULTURE HANDBOOK 2 5 2, U.S. DEPT. OF AGRICULTURE

TABLE 33.—Panel member sizesfor crates^ designed for a net load of 20ft00 pounds—Continued

8-FOOT-WIDE CRATE

Length Member

Crate height

4 feet 6 feet 8 feet 10 feet 12 feet

Ft,

10

12

16

20

24

28

32

Upper frame

Lower frame

Strut

Diagonal

L^pper frame

Lower frame

Strut

Diagonal

Upper frame

Lower frame

Strut

Diagonal

Upper frame

Lower frame

Strut

Diagonal

Upper frame

Low^er frame

Strut

Diagonal

Upper frame

Lower frame

Strut

Diagonal

Upper frame

Low^er frame

Strut

Diagonal

Upper frame

Lower frame

Strut

Diagonal

Upper frame

Lower frame

Strut

Diagonal

In.

bv 4

bV 4

by 6

bv 6

bV 6

by 4

by 6

by 6

bVe

by

by

by

by

by

by

by

by

by

by

by

In.

4

4

6

6

4

4

6

6

4

42

6

by 6 2

by 4

by 4

bV 6

bV 8 3

by 42

by 42

bV 6

by 8 3

by 42

by 4

by 6

by 10 '

by 4*

by 44

by 6^

by

by

by

by

by

by

by

2

2

2

2

2

2 by 6 2

2 by 6

2 by 4

2 bV 6

by 6

by 6

by

by

by

bV

by

by

bV

bV

bV

by

by

by 6 2

by 4

by 42

by 6

by 6 2

by 4

by

by

by

by

by

4

6

82

4

4

by 8

In.

by 4

by 4

by 6

bV 6

by 4

bV 4

by 6

by 8

by 6

by 4

by 6

by 8

by 6

by 4

by 6

by 6

by 6

by 4

bV 6

by 8

by 6

by 4

by 4

by 8

bV 6

b> 4

by 4

bV 8

by 6 2

bV 4

bV 42

by 8

by 6 3

by 4

by 42

by 8

In.

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by

bV

by

by

by

by 8

by 6

by

by

by

by

by

by

by 8

by 6

by 4

by 4

by 8

by 6

by 4

by 4

bV 8

In.

by 8

by

by

by

by

by

by

by

by

by

by

by

by

by

by

by 8

by 8

by 6

bV 4

by 8

by 6

2 by

2 by

by

by

by

by

by

6

4

4

8

6

4

4

by 8

See footnotes at end of table.
WOOD CRATE DESIGN MANUAL 111

TABLE 33.—Panel member sizes for crates ^ designed for a net load of 20fl00 pounds—Continued

10-FOOT-WIDE CRATE

Length Member

Crate height

4 feet 6 feet 8 feet 10 feet 12 feet

Ft. rÜDDer frame

In.

2 by 4

2 by 4

2 by 6

2 by 6

2 by 6

2 by 4

2 by 6

2bv6

2 by 6

2 by 4

2 by 4

2 by 6

2 by 6

2 by 4

2 by 4

2 by 6

2 by 6

2 by 4

2 by 4 2

2 by 6

2 by 6 2

2 by 4

2 by 4

2 by 6

2 by 8^

2 by 42

2 by 4 2

2 by 6

2 by 8 3

2 by 42

2 by 4

2 by 6

2 by 10 4

2 by 44

2 by 44

2by 6 4

In.

2 by 4

2 by 4

2 by 6

2 by 6

2 by 6

2 bv 4

2 by 6

2 by 8

2 by 6

2 by 4

2 by 6

2 by 6

2 by 6

2 by 4

2b> 6

2 by 6

2 by 6

2 by 4

2 by 4

2 by 6

2 by 6

2 by 4

2 by 4

2 by 6

2 by 6 2

2 by 4

2 by 4 2

2 by 6

2 by 6 2

2 by 4

2 by 4

2 by 6

2 by 8 2

2 by 4

2 by 4

2 by 8

In.

2 by 4

2 by 4

2 by 6

2 by 6

2 by 4

2 by 4

2 by 6

2 by 8

2 by 6

4 by 4

2 by 6

2 by 8

2 by 6

2 by 4

2 by 6

2 by 6

2 by 6

2 by 4

2 by 6

2 by 8

2 by 6

2 by 4

2 by 4

2 by 8

2 by 6

2b>4

2 by 4

2 by 8

2 by 6 2

2 by 4

2 by 42

2 by 8

2 by 8 2

2 by 4

2 by 42

2 by 8

In.

2 by 4

2 by 4

2 by 6

2 by 8

2 by 4

2 by 4

2 by 6

2 by 6

2 by 4

2 by 4

2 by 6

2 by 6

2 by 4

2 by 4

2 by 6

2 by 8

2 by 6

2 by 4

2 by 6

2 by 8

2 by 6

2 by 4

2 by 8

2 by 8

2 by 6

2 by 4

2 by 8

2 by 8

2 by 6

2 by 4

2 by 4

2 by 8

2 by 6

2 by 4

2 by 4

2 by 8

In.

2 bv 4

Lower frame 2 by 4

6

1 Strut __- 2 by 6

Diaconal _ _ _ 2 by 6

Í Upper frame 2 by 4

Lower frame _ _ _ _ 2 by 4

8

1 Strut _- _ _ _ 2 by 6

Diagonal- __ 2 by 8

["Upper frame 2 by 4

Lower frame _ _ _ 2 by 4

10 1 Strut 2 by 6

Diagonal -_ __ ____ 2 by 6

f Upper frame _ _ _ - 2 by 4

Lower frame 2 by 4

12 1 Strut - - - 2 by 6

Diaconal ___ -_

2 by 6 2

f Upper frame __ ___ __ 2 by 4

Lower frame ____ _ 2 by 4

16 1 Strut __-_ _ - -- 2 by 8

Diaconal 2 by 6

rUDDer frame __ _ _ _ 2 by 6

Lower frame 2 by 4

20 1 Strut -- - - --

2 by 8

Diaconal 2 by 8

fTlDDPr frame _ _ _ 2 by 6

Lower frame 2 by 4

24 1 Strut - _--

2 by 8

Diaconal 2 by 8

rUüDer frame 2 by 6

Lower frame 2 by 4

28 1 Strut 2 by 4

Diagonal - -

2 by 8

fllnDer frame 2 by 6

Lower frame 2 by 4

32 1 Strut _ _ _

2 by 4

Diaconal 2 by 8 2

1 Sizes are for uniform loads, but apply also to concentrated loads except as indicated.

2 For concentrated loads, increase the member size to the next larger size, as a 2 by 4 to a 2 by b.

3 For concentrated loads, increase the member size to the second larger size, as a 2 by 6 to a 2 by lU.

* Crates require special design for a concentrated load.

692-318 0—64 8
112 AGRICULTURE HANDBOOK 2 5 2, U.S. DEPT. OF AGRICULTURE

Length

TABLE 34.—Panel member sizes for crates^ designed for a net load of 25,000 pounds

4-FOOT-WIDE CRATE

Member

Crate height

4 feet 6 feet 8 feet 10 feet 12 feet

Ft.

10

12

16

20

24

28

32

Tapper frame

LoAvcr frame

Strut

.Diagonal

Upper frame

Lower frame

Strut

.Diagonal

L^pper frame

Lower frame

Strut

, Diagonal

'Upper frame

Lower frame

Strut

.Diagonal

Upper frame

Lower frame

Strut

.Diagonal

I I^pper frame

Tjower frame

[Strut

[Diagonal

[I^pper frame

I TiOwer frame

I Strut

[Diagonal

flapper frame

I Lower frame

iStrut

[Diagonal

ÍL'pper frame

I TiOwer frame

IStrut

[Diagonal

In.

V)v 6

bv 4

1)V G

bv 6

by 6

by 4

l/y 6

l)y 6

by 6

by

by

by G

bV 6

l)y 4

bV 4

by G

by 6

bV S -

bV 4

by 4

by 6

by 8 3

by 4 3

by 4 3

by 6 3

by 10 3

by 4 3

by 4 3

bV S 3

by 12 3

2 l)y 6 3

2 by 4 3

2 ])y 8 3

In.

2 by 6

2 by 4

2 by G

2 l)y 8

2 by 6

2 bV

2 by

2 bv

2 l)y

2 bV

2 by

2 })y

2 by

2 bV

2 bV 6 2

2 by 8

2 })y G

2 1)V 4

2 })v 4

2 by G

2 by G

2 })v 4

2 bV 4

2 by 8

2 by G ^

2 l)y 4

2 by 4 2

2 bV 8

2 l)V 8 2

•J by

2 by

2 l^V

2 by

2 l)y

2 ])y

2 by

4

4

8

82

4

4

8

In.

2 )jy

2 l)y

2 bv

2 bv

»)¥

bV

l)y

by

by

In^

2 by

2 bV 8

2 bV G

2 bv 4

2 bV G

2 bV 8

2 by G

2 bV 4

2 by

2 by

2 by

2bV

2 bV

2 bV

2 by

2 by

2 by

2 bV

2 by

2 by

2 bV

2 bV

2 by

2 by

2 liV

2 by

8

8

6

4

4

8

G

4

4

8

G2

4

42

8

82

4

4^

82

In.

2 by 4

2 by 4

2 by 6

2 by 8

2 by 4

2 by

2 bV

2 bV

2 bV

2 bV

2 bV 6 2

2 bV 8

2 by 4

2 bV 4

2 bV 8

2 bV 8

2 bV G

2 bV 4

2 bV 8

2 bV 8

2 bV

2bV

2 bV

2 bV

2 bV

2 bv

2 bV

2 bV 8

2 by 6

2 bV

2bV

2bV

2 bV

2 by

2 bV

4

4

G2

G

4

4

by 8

In.

by 4

by 4

by 6

by 8

by

by 4

bv 6

by 8

by 4

by 4

by 8

by 6

by 4

by 4

bV 8

by 8

by 6

by 4

bV 8

bV 8

hy

by

bv

by

bv

by

by 8

by 8

by 6

by 4

by 4

bv 8

by 6

bV 4

2 bV 4

2 by 8

See footnotes at end of table.
WOOD CRATE DESIGN MANUAL 113

TABLE 34.—Panel member sizes for crates^ designed for a net load oj25ft00 pounds—Continued

6-FOOT-WIDE CRATE

Length

Ft.

12

16

20

24

28

32

Upper frame.

Lower frame.

Strut

Diagonal

Upper frameLower frame .

Strut

Diagonal

Upper frame.

Lower frame.

Strut

Diagonal

Upper frame.

Lower frame .

Strut

.Diagonal

Upper frame.

Lower frame.

Strut

, Diagonal

'Upper frame.

Lower frame.

I Strut

[Diagonal

Upper frameI Lower frame.

I Strut

[Diagonal

[Upper frameI Lower frame.

Strut

[Diagonal

¡Upper frameLower frame.

Strut

Diagonal

Member

Crate height

4 feet 6 feet 8 feet 10 feet 12 feet

In. In. In. In. In.

2 by 6 2 by 6 2 by 4 2 by 4 2 by 4

2 by 4 2 by 4 2 by 4 2 by 4 2 by 4

2 by 6 2 by 6 2 by 6 2 by 6 2 by 8

2 by 6 2 by 8 2 by 8 2 by 8 2 by 8

2 by 6 2 by 6 2 by 42 2 by 4 2 by 4

2 by 4 2 by 4 2 by 4 2 by 4 2 by 4

2 by 6 2 by 6 2 by 6 2 by 8 2 by 8

2 by 6 2 by 8 2 by 8 2 by 6 2 by 8

2 by 6 2 by 6 2 by 6 2 by 4 2 by 4

2 by 4 2 by 4 2 by 4 2 by 4 2 by 4

2 by 4 2 by 6 2 by 8 2 by 8 2 by 8

2 by 6 2 by 6 2 by 8 2 2 by 8 2 by 8

2 by 6 2 by 6 2 by 6 2 by 4 2 by 4

2 by 4 2 by 4 2 by 4 2 by 4 2 by 4

2 by 4 2 by 6 2 2 by 8 2 by 8 2 by 8

2 by 6 2 by 8 2 by 8 2 by 8 2 by 8

2 by 6 2 by 6 2 bv 6 2 by 6 2 by 6

2 by 4 2 by 4 2 by 4 2 by 4 2 by 4

2 by 42 2 by 4 2 by 8 2 by 8 2 by 8

2 by 6 2 by 6 2 by 8 2 by 8 2 by 8

2 by 8 2 2 by 6 2 bv 6 2 by 6 2 by 6

2 by 4 2 by 4 2 by 4 2 by 4 2 by 4

2 by 4 2 by 4 2 by 4 2 by 8 2 by 8

2 by 8 2 by 8 2 by 8 2 by 8 2 by 8

2 by 10 3 2 by 8^ 2 by 8 2 by 8 2 by 6

2 by 4 3 2 by 4 2 by 4 2 by 4 2 by 4

2 by 43 2 by 4 2 2 by 4 2 by 8 2 by 8

2 by 8 3 2 by 8 2 by 10 2 by 8 2 by 8

2 by 10 3 2 by 8 2 2 by 8 2 2 by 6 2 by 6

2 bv 4 3 2 by 4 2 by 4 2 by 4 2 by 4

2 by 43 2 by 4 2 by 4^ 2 by 4 2 by 4

2 by 8 3 2 by 8 2 by 8 2 by 6 2 2 by 8

2 by 12 3 2 by 8 2 2 by 8 2 2 by 8 2 by 6

2 by 6 3 2 by 4 2 by 4 2 by 4 2 by 4

2 by 4 3 2 by 4 2 by 44 2 by 4 2 by 4

2 by 8 3 2 by 8 2 by 10 2 by 8 2 by 8 2

See footnotes at end of table.
114 AGRICULTURE HANDBOOK 2 5 2, U.S. DEPT. OF AGRICULTURE

TABLE 34.—Panel member sizesjor crates ^ designedjor a net load oj25ft00 pounds—Continued

8-FOOT-WIDE CRATE

Length Member

Crate height

4 feet 6 feet 8 feet 10 feet 12 feet

Ft.

10

12

16

20

24

28

32

Upper frameLower frame.

Strut

Diagonal

Upper frameLower frame.

Strut

Diagonal

Upper frame.

Lower frame.

Strut

Diagonal

'Upper frame.

Lower frame.

Strut

Diagonal

Upper frameLower frame.

Strut

Diagonal

Upper frameLower frame.

Strut

Diagonal

Upper frame.

Lower frame.

Strut

Diagonal

Upper frame.

Lower frame.

Strut

Diagonal

'Upper frame.

Lower frame.

Strut

^Diagonal

In.

by 6

by

by

by

by

by

by 6

by 6

by

by

by

by

by

by

by

by 6 2

by 8

by 4

by 42

by 8

by 8 2

by 4

by 4

by 8

by 10 3

bv 43

by 4 3

by 8 3

by 10 2

by 43

by 43

by 8 3

by 12 Í

by 6 3

by 43

by 8 3

In.

2 by 6

2 by 4

2 by 6

2 by 8

2 by 6

2 by 4

2 by 6 =

2 by 8

2 by 6

2 by

2 by

2 by

2 by

2 by

2 by 8

2 by 8

2 by 6

2 by 4

2 by 4

by 8

by 6

by 4

by 4

by 8

by 8^

by 4

2 by 4^

2 by 8

by 8-

by 4

by 4

by 8

by 8'

by 4

by 4

by 8

In.

by 4

by 4

by 8

by 8

by 42

by 4

by 8

by 8

by 6

by 4

by 8

by 8 2

by 6

by 4

2 by 8

2 by 8

by 6

by 4

by 8

by 8

by 6

by 4

by 4

by 8

by 8

by 4

2 by 4

2 by 10

by 8 2

by 4

by 44

by 10

by 8 2

by 4

by 4^

by 10

In.

by 4

by 4

by 8

by 8

by 4

by 4

by 8

by 6

by 4

by 4

by 8

by 8

by 4

by 4

by 8

by 8

by 6

by 4

by 8

by 8

by 6

by 4

by 8

by 8

2 by 8

2 by 4

by 8

by 10

by 8

by 4

by 4

by 6 2

by 8

by 4

by 4

by 10

In.

2 by 4

2 by 4

2 by 8

2 by 8

2 by 4

2 by 4

2 by 8

2 by 8

2 by 4

2 by 4

2 by 8

2 by 8

2 by 4

by 4

by 8

by 8

by 6

by 4

by 8

by 8

by 6

by 4

by 8

by 8

by 6

by 4

by 8

by 8

by 6

by 4

2 by 6

2 by 8

2 by 6

2 by 4

2 by 6

2 by 10

See footnotes at end of table.
WOOD CRATE DESIGN MANUAL 115

TABLE 34.—Panel member sizes for crates^ designedJor a net load oJ26fl00 pounds—Continued

lO-FOOT-WIDE CRATE

Length Member

Crate height

4 feet 6 feet 8 feet 10 feet 12 feet

Ft.

10

12

16

20

24

28

32

iUpper frame.

Lower frame.

Strut

Diagonal

IUpper frame.

Lower frame.

Strut

Diagonal

IUpper frame.

Lower frame.

Strut

Diagonal

iUpper frame.

Lower frame.

Strut

Diagonal

IUpper frame.

Lower frame.

Strut

Diagonal

iUpper frame.

Lower frame.

Strut

Diagonal

ÍUpper frame.

J Lower frame.

Strut

[Diagonal

I Upper frame.

Lower frame.

Strut

Diagonal

ÍUpper frame.

J Lower frame.

[Strut

[Diagonal

In.

by 6

by 4

hy 6

by 6

by 6

by 4

by 6

by 6

by 6

by 4

by 4

by 6

by 6

by 4

by 4

by 8

by 6

bv 4

by 4 2

by 8

by 8 2

by 4

by 4

by 8

by 10 3

by 43

by 4 3

by 8 3

by 10 3

by 43

by 43

by 8 3

bv 12 3

bv 6 3

by 43

by 8 3

In. In,

by 6 2 by 4

by 4 2 by 4

bv 6 2 by 8

by 8 2 by 8

bv 6 2 by 42

by 4 2 by 4

by 8 2 by 8

by 8 2 by 8

by 6 2 by 6

by 4 2 by 4

by 8 2 by 8

bv6 2 by 8 2

by 6 2 by 6

by 4 2 by 4

by 8 2 by 8

by 8 2 by 8

by 8 2 by 6

by 4 2 by 4

by 4 2 by 8

by 8 2 by 10

by 6 2 by 6

bv4 2 by 4

by 4 2 by 4

by 8 2 by 8

by 8 2 2 by 8

by 4 2 by 4

bv 4^ 2 by 4

by 8 2 by 10

by 8 2 2bv82

by 4 2 by 4

by 4 2 bv 4 4

by 8 2 by 10

by 10 2 bv8 2

by 4 2 by 4

by 4 2 by 4 4

by 8 2 by 10

In.

by 4

by 4

by 8

by 8

by 4

by 4

by 8

by 6

by 4

by 4

by 8

by 8

by 4

by 4

by 8

by 8

by 6

by 4

by 8

bv 8

2 by 6

2 by 4

by 8

by 8

by 8

by 4

by 8

2 by 10

2 by 8

by 4

by 6

bv8 2

by 8

by 4

by 6

by 10

In.

by 4

by 4

by 8

by 8

by 4

by 4

by 8

by 10

2 by 4

2 by 4

by 8

by 8

by 4

by 4

by 8

by 8

by 6

by 4

by 8

by 8

by 6

by 4

by 8

by 8

by 6

by 4

by 8

by 10

2 by 6

2 by 4

2 by 6

2 by 10

2 by 6

2 by 4

2 by 6

2 by 10

1 Sizes are for uniform loads but apply also to concentrated loads except as indicated.

2 For concentrated loads, increase the member size to the next larger size, as a 2 by 4 to a 2 by 6.

3 Crates require special design for a concentrated load. o u m

^ For concentrated loads, increase the member size to the second larger size, as a 2 by 6 to a 2 by lU.
116 AGRICULTURE HANDBOOK 2 5 2, U.S. DEPT. OF AGRICULTURE

TABLE 35.—Panel member sizes for crates^ designed for a net load oj 30,000 pounds

4-FOOT-WIDE CRATE

Length Member

Crate height

4 feet 6 feet 8 feet 10 feet 12 feet

Ft.

10

12

16

20

24

28

32

Upper frame

Lower frame

Strut

Diagonal

Upper frame

Lower frame

Strut

^ Diagonal

'Upper frame

Lower frame

Strut

L Diagonal

Upper frame

Lower frame

Strut

Diagonal-. _

I Upper frame

Lower frame

Strut

.Diagonal

Upper frame

Lower frame

Strut

[Diagonal

Upper frame

I Lower frame

I Strut

[Diagonal

r Upper frame

I Lower frame

Strut

[Diagonal

Upper frame

Lower frame

Strut

[Diagnoal

In.

by 6

by 4

by S

by 8

by 6

by 4

by 8

by 8

by 6

by

by

by

by

by

bv

bV

by 8

bv 4

bv 42

by 8

bv 8 2

bv

by

by

4

4

8

by 10^

by 44

by 44

by 8^

by 12 4

by 6^

by 44

by 8^

by 12^

bv 6 4

by 4^

by 8 4

In.

by 6

by 4

by 8

bv 8

bv 6

by 4

by 8

bv 10

2

2

2

2

2

2 by

2 by

2 by

2 bv

2 by

2 bv

2 by

2 by

bv

bV

by

by

by

bv

by

bv

by

by

by

by 8

by 8 3

by 4

2 by 4

2 by 8

2 by 10 =

2 by 43

2 by 4

2 by 10

6

4

8

8

6

4

4

8

8

4

4

8

S3

4

42

In.

2 by 4

2 by

by

by

by

by

bv

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2 by

2

2

2 by

2 bv

2 by

4

8

8

6

4

10

bv 10

by 6

by 4

by 10

by 10

bv 6

by 4

by 8

bv 8

bv 6

4

by 10

bv 10

by 10

2 by 8

2 by 4

2 by 4 3

2 by 10

by 8 3

by 4

by 42

by 10

by 8 3

by 43

by 42

by 10

In.

by 4

by 4

by 8

by 8

by 4

by 4

2 by 8

2 by 8

by 4

by 4

bv 8

by 8

by 4

by 4

by 8

by 10

2 by 6

2 bv 4

by 8

by 8

b> 6

by 4

bv 8

bv 8

by 8

2 by 4

5 by 8

by 10

by 8

by 4

by 4

by 10

by 6 3

by 4

by 6

In.

by 4

by 4

by 8

by 8

bv 4

by 4

by 8

by 10

by 4

by 4

by 8

by 8

by 4

by 4

by 8

bv 10

by 6

b> 4

b> 8

by 8

bv 6

by 4

by 8

by 8 3

by 6

by 4

by 8

by 10

2 by 6

2 by 4

by 6

by 10

by 6

by 4

bv6

2 by 10 2 bv 10

See footnotes at end of table.
WOOD CRATE DESIGN MANUAL 117

TABLE 35.—Panel member sizes for crates ^ designed for a net load of 30,000 pounds—Continued

6-FOOT-WIDE CRATE

Length Member

Crate height

4 feet 6 feet 8 feet 10 feet 12 feet

Ft.

10

12

16

20

24

28

32

Upper frame.

Lower frame_

Strut

Diagonal

Upper frame.

Lower frame.

Strut

Diagonal

Upper frame.

Lower frame _

Strut

^Diagonal

'Upper frame.

Lower frame.

StrutDiagonal

Upper frameLower frame_

Strut

Diagonal

Upper frame.

Lower frame_

Strut

Diagonal

Upper frame.

Lower frame _

Strut

Diagonal

Upper frame.

Lower frame .

Strut

Diagonal

Upper frame.

Lower frame _

Strut

.Diagonal

In.

by 6

by 4

by 8

by 8

by 6

by

by

by

by

by

by

by 8

by 6

by 4

by 4

by 8

by 8

bv 4

by 42

by 8

by 8 2

by 4

by 4

by 8

by 10 4

by 4^

by 44

by 8^

by 12^

by 6^

by 44

by 8 4

by 12^

bv 8 4

by 44

by 8 4

In.

2 by 6

2 by 4

2 by 8

2 by 8

2 by 6

by 4

by 8

bv 10

by 6

by 4

bv 8

bv 8

2 by 6

2 by 4

bv 8

bv 8

by 6

by 4

by 4

2 by 8

2 by 8

bv 4

by 4

by 10

by 8 2

by 43

by 42

by 8

by 10

by

by

by

by

43

4

8

10 =

by 43

by 4

by 10

In.

2 by 43

2 by 4

2 bv 8

2 by 8

2 by 6

2 by 4

by 10

by 10

2 by

2 by .

2 by 10

2 by 10

2 by 6

2 bv 4

2 by 8

2 bv 8

2 by 6

2 by 4

2 by 10

2 by 10

2 bv 6

2 by 4

2 by 4

2 bv 10

2 bv 8

2 by 4

2 by 4 3

2 by 10

2 bv 8 3

2 by 4

2 by 6 3

2 by 10

2 by 8 3

2 by 43

2 by 6 3

2 by 10

In.

by 4

by 4

by 8

by 10

by 4

by 4

by 8

by 8

by 4

by 4

by 8

by 8

by 4

by 4

by 8

by 10

by 6

bv 4

by 8

by 10

2 by 6

2 by 4

2 by 8

2 by 8

2 by 8

2 by 4

2 by 8

2 by 10

2 by 8

2 by 4

by 6

by 10

by 8

by 4

by 6

by 10

In,

by 4

by 4

by 8

by 8

by 4

by 4

by 8

by 10

by 4

2 by 4

2 by 8

by 8

by 4

by 4

by 8

by 10

by 6

bv 4

2 by 8

2 by 8

2 by 6

2 by 4

2 by 8

2 bv 10

2 by 6

2 by 4

2 by

by

by

bv

by

by

by 8

by 4

by 6

by 10

10

10

6

4

6

10

See footnotes at end of table.
118 AGRICULTURE HANDBOOK 2 5 2, U.S. DEPT. OF AGRICULTURE

TABLE 35.—Panel member sizesfor crates ^ designed for a net load oj SOßOO pounds—Continued

8-FOOT-WIDE CRATE

Length Member

Crate height

4 feet 6 feet 8 feet 10 feet 12 feet

Ft.

10

12

16

20

24

28

32

[Upper frame

I Lower frame

I Strut

[Diagonal

[Upper frame

I Lower frame

[Strut

[Diagonal

Upper frame

Lower frame

Strut

, Diagonal

'Upper frame

Lower frame

Strut

.Diagonal

Upper frame.

Lower frame.

Strut

Diagonal

Upper frame.

Lower frame.

Strut

Diagonal

Upper frame.

Lower frame.

Strut

Diagonal

Upper frame.

Lower frame.

Strut

Diagonal

Upper frame.

Lower frame.

Strut

Diagonal

In.

by 6

by 4

by 8

by 8

by 6

by 4

by 8

by 8

by 6

by 4

by 4

by 8

by 6

by 4

by 4

by 8

by 8

by 4

by 4 2

by 8

by 8 2

by 4 3

by 4

by 8

by 10^

by 4 4

by 44

by 8^

by 12 4

by 6 4

by 4^

by 8 4

by 12 4

by 8 4

by 4^

by 8 4

In.

by 6

by 4

by 8

by 8

by 6

by 4

by 8

by 10

by 6

by 4

by 8

by 8

by 6

by 4

by 8

by 8

by 6

by 4

by 4

by 8

by 8

by 4

by 4

by 10

by 8 2

by 4 3

by 6 3

by 10

by 10 3

by 4 3

by 6

by 10

by 10 3

by 4 3

by 6

by 10

In.

by 6

by 4

by 8

by 8

bv 6

by 4

by 10

by 10

by 6

by 4

by 10

by 10

by 6

by 4

by 8

by 10

by 6

by 4

by 10

by 10

by 6

by 4

by 6

by 10

by 8

by 4

by 6

by 10

by 8 3

by 4

by 6 3

by 10

by 10

by 4 3

by 6 3

by 10

In. In.

by 6 2 by 6

by 4 2 by 4

by 8 2 by 8

by 10 2 by 8

by 4 2 by 4

by 4 2 by 4

by 8 2 by 8

by 8 2 by 10

by 4 2 by 4

by 4 2 by 4

by 8 2 by 8

by 8 2 by 8

by 4 2 by 4

by 4 2 by 4

by 8 2 by 8

by 10 2 by 10

by 6 2 by 6

by 4 2 by 4

by 8 2 by 8

by 10 2 by 8 3

by 6 2 by 6

by 4 2 by 4

by 8 2 by 10

by 10 2 by 10

by 8 2 by 8

by 4 2 by 4

by 10 2 by 10

by 10 2 by 10

by 8 2 by 8

by 4 2 by 4

by 6 2 by 6

by 10 2 by 10

by 8 2 by 8

by 4 2 by 4

by 6 2 by 6

by 10 2 by 10

See footnote« at end of table.
WOOD CRATE DESIGN MANUAL 119

TABLE 35.--Panel member sizesfor crates^ designed for a net load oJSOfiOO pounds—ConiiuMeá

10-FOOT-WIDE CRATE

Length

Ft

10

12

16

20

24

28

32

IUpper frameLower frame.

Strut

Diagonal

I Upper frameLower frame _

Strut

Diagonal

I Upper frame.

Lower frame.

Strut

Diagonal

I Upper frame.

Lower frame.

Strut

Diagonal

Upper frame.

Lower frame.

' Strut

.Diagonal

Upper frame.

Lower frame.

"Strut

Diagonal

I Upper frame.

Lower frame.

Strut

Diagonal

Upper frame.

Lower frame_

Strut

Diagonal

'Upper frame.

Lower frame.

Strut

.Diagonal

Member Crate height

4 feet

In.

by 6

by 4

by 8

by 8

by 6

by 4

by 8

by 8

by 6

by 4

by 4

by 8

by 6

by 4

by 4

by 8

by 8

by 4

by 42

by 8

by 10 3

by 43

by 4

by 8

by 10*

by 4'

by 4'

by 8

by 12

by 6

by 4

by 8'

by 12'

by 8

by 4

by 8

6 feet

In.

2 by 6

2 by 4

2 by 8

by 8

by 6

by 4

by 8

by 10

by 6

by 4

by 8

by 8

by 6

by 4

by 8

by 8

by 6

by 4

by 4

by 8

by 10

by 4

by 4

by 10 3

by 8 2

by 43

by 6 3

by 10

by 10 3

by 43

2 by 6

2 by 10

2 by 10 3

2 by 43

2 by 6

2 by 10

8 feet

In.

2 by 6

2 by 4

2 by 8

2 by 8

2 by 6

2 by 4

2 by 10

2 by 10

2 by 6

2 by 4

2 by 10

2 by 10

2 by 6

2 by 4

2 by 8

by 10

by 6

by 4

by 10

by 10

by 6

by 4

by 6

by 10

by 8

by 4

by 6

by 10

by 8 3

by 4

by 6 3

by 10

by 10

2 by 43

2 by 6 3

2 by 12

10 feet

In.

2 by 4

2 by 4

2 by 8

2 by 10

2 by 4

by 4

by 8

by 8

by 4

by 4

by 8

by 8

by 4

by 4

by 8

by 10

by 6

by 4

by 10

by 10

by 6

by 4

by 10

by 10

by 8

by 4

by 10

by 10

by 8

by 4

by 6

by 10

by 8

by 4

by 6

by 10

12 feet

In.

2 by 4

2 by 4

by 8

by 10

by 4

by 4

by 8

2 by 10

2 by 4

2 by 4

2 by 8

2 by 8

2 by 4

2 by 4

2 by 8

2 by 10

2 by 6

2 by 4

by 10

by 10

by 6

by 4

by 10

by 10

by 8

by 4

by 10

by 10

by 8

by 4

by 6

by 10

by 8

by 4

by 6

by 12

* Sizes are for uniform loads but apply to concentrated loads except as indicated.

2 For concentrated loads, increase the member size to the second larger size, as a 2 by 6 to a 2 by 10.

3 For concentrated loads, increase the member size to the next larger size, as a 2 by 4 to a 2 by 6.

* Crates require special design for a concentrated load.
APPENDIX IL DETAILS OF SHIPPING

MARKING

All crates must have some markings on them

to show their destination, to whom they are consigned, and the name of the consignor. Many

crates also have markings that describe the contents, for advertising or storage information. In

some government shipments, however, especially

in time of war, a code is used to minimize pilfering.

The code marking is more important on export

shipments, particularly for containers that will

be subjected to numerous handlings.

The Interstate Commerce Commission requires

special marking of dehcate or dangerous articles,

for the protection of both the article and those

handling the container. Label requirements vary

a great deal between items. For this reason, all

special markings and shipping instructions should

conform to the latest ICC Regulations. These

regulations cover the land and water transporation

of explosives and other dangerous articles and

include specifications for the required shipping

containers.

Other markings used on the exteriors of many

crates, especiall}^ those destined for foreign areas,

concern handling and opening. A container that

may be reused is often marked ^'Reusable Container" and, if opening directions are required,

^To Open—Remove End" or a similar phrase

might be employed. Inspection doors or inspection ports should have suitable markings.

Packed crates over 10 feet long and crates with

their balance point off center should be marked to

indicate the balance point. This is usually accomphshed by stenciling or painting a stripe on each

side of the crate, generally extending about 18

inches from the lower edge of each side. The

words '^Center of Balance ""should appear next to

the stripes. A convenient method of locating

these stripes is by moving the loaded crate over

a roller to find the center of balance.

When grabhook handling is anticipated, an area

is marked over the center of balance on each side

near the top of the crate at the reinforcins; joists.

The words ^'Grabhook Here" should be painted

or stenciled near this marked area. Crates with

provisions for slings under the ends of the skids

should have a stripe located at each lower corner

of the sides with the words '^Shng Here."

It is often helpful to include markings to reduce

the chance that the crate will be placed on its

side. Ordmarily the presence of the skids is

enough to indicate the correct position durins;

storage or shipping. However, hio-h, narrow

crates may be placed on their sides; if heavy boxes

120

or crates are placed on them, their contents may

be damaged. The use of a well-defined arrow

and the word ^'Up" marked on each side of the

crate near the top is a precaution that may pay

dividends in placing and handling odd-size crates.

For the convenience of the personnel concerned

with the transportation of the crate, its dimensions, weight, and volume might well be marked

on the exterior. A bill of lading is needed on

many crates to assist in unpacking, especially

wehere a number of items are included in one crate.

This minimizes the chance of missing small items.

While ordinary ink or even crayon may be used

for marking crates on some local shipments,

more permanent materials should be used for normal shipping conditions. Waterproof ink or paint

should be used for marking crates to be shipped

overseas or that might be exposed to weathering or placed in storage.

The International Union of Marine Insurance

has found that proper marking is very important

in the safe arrival of export and other shipments.

It has recommended the following fundamental

marking rules:

1. Unless local regulations prohibit, use blind

marks where goods are susceptible to pilferage.

Change the marks periodically to prevent handlers

from becoming familiar with them. Trade names

and consignee's or shipper's names should not

indicate the nature of the contents.

2. Consignee identification marks and port

marks that show destination and transfer points

should be large, clear, and appHed only by stencil

with waterproof ink. They should be applied

on two faces of the container, preferably sides

or ends.

3. The proper cautionary marks in Enghsh

and in the language of destination should be used

when necessarj^. These include such cautions

as ^^Handle With Care," ^^Glass," and ^^Use No

Hooks." While the marks do not always insure

proper handling, they will often pay for the httle

trouble required to apply them.

PACKING LISTS

The packing list may be similar to a bill of

lading but have more descriptive detail on the

contents. It should be made at least in triplicate;

one copy is retained by the shipper, another goes

with the invoice, and a third is packed with the

item, in a location where it cannot be lost or

damaged and is protected from the weather.

The interior of the crate near or on a removable

end or top is often used for this purpose. The
WOOD CRATE DESIGN MANUAL 121

recipient can then check the contents and note

any missing items.

SHIPPING LOSS PREVENTION

Port and transportation facihties have improved

in many countries since World War II, but losses

still occur from theft, pilferage, nondelivery,

breakage, and so forth. Losses can be minimized by using proper containers and good

packing and anchoring.

For example, the findings of an insurance

company ^ reveal that 80 percent of all losses on

overseas shipments for the 5 j^ears 1955 to 1959

were preventable, as shown in the following

tabulation:

All losses

1955-59

Cause of loss {-percent)

Major casualties, largely nonpreventable (sinkings,

strandings, fires, collisions) 20

Preventable losses :

Sea water and heavy weather 5

Theft, pilferage, and nondelivery 21

Handhng and stowage 41

Water damage 13

The vital importance of preventing these losses

has been emphasized by the recommendations of

the International Union of Marine Insurance.

These recommendations concern, for the most

part, the proper construction of cartons, nailed

wood boxes, crates, and other containers. The}^

are aimed at correcting three principal difficulties:

(1) Improper or inadequate securing of the item

to the crate base, (2) w^eak or insufficiently supported top construction, and (3) inadequate

frame members or skids. The use of grabhooks

on unsupported panels, lack of diagonal bracing,

and lack of handling markings were other causes

for damage.

The construction outlined for the sheathed

and unsheathed crates in this publication is more

than adequate to withstand the handling hazards

that ordinarily cause damage.

EXPORT SHIPPING

Export shipping rates are usually based upon

a ton (generally 2,240 pounds, but sometimes only

2,000 pounds) or on 40 cubic feet, whichever

produces the greater tariff. General!}^ speaking

the volume rate applies, unless the crate or box

2 240 weighs -—-— or 56 pounds per cubic foot. Since

most material shipped has a much lower density

than this, it is important to decrease the cubic

displacement of a crate. A loaded crate that

weighs 27 pounds per cubic foot will cost twice as

much per pound to ship as a crate of the same

volume that weighs 54 pounds per cubic foot.

^ Insurance Company of North America. Ports of the

World. Ed. 6. Philadelphia 1, Pa.

ANCHORING CRATES TO SHIP SURFACES

Large crates assigned to foreign ports are often

stored on the deck of the ship during transport.

When it is known that crates will be shipped on

decks of ships and must be anchored to them,

preparations during construction usually consist

of drilling holes into the outside skids to receive

eyebolts. The holes should be centered between

the top and bottom of the skids, 8 to 12 inches

from the ends. The base of the crate should be

fitted with not less than four eyebolts. The

crate should be anchored with rods, but when their

use is impractical, wire rope of equivalent strength

may be used. These tie rods or wire ropes are

fastened to pad eyes welded to the deck. Tie rods

should be provided with turnbuckles, and the

ends of the wire ropes secured with at least three

cable clamps. If the crate is high or top loaded,

supplementary lashing over the top may be used

as necessary to relieve racking strains and as an

aid to anchoring.

CARLOADING CRATES

The countless pages of print devoted during

the last half century to the loading and stowing

of freight in rail shipments testify to the economic

importance of the carloading phase of materials

handling. Damage-free delivery is obviously of

paramount importance. Consequently, carloading, blocking, and bracing are critical steps in the

handling of crated items. If they are insecure

or inadequate and the item is damaged, the skill

and labor expended to produce and package it

are wasted.

Freight Classification

Committees classify commodities shipped by

rail so that ratings will be uniform. The freight

rates that apply to the classifications are established by the individual railroads through their

rating committees. The container in which an

item is shipped and the packing protection given

an article are factors used to determine classification ratings. The rules provide specific packing

for a large number of commodities and give

more or tess definite packing specifications for

those not fisted. The carriers may refuse to

accept any article tendered them for transportation

if it is not packed according to their rules. If

they accept, the}^ may charge a penalty.

Car Impacts

Proper application of the basic principles of

good carloading will protect crates against the

normal impacts to which shipments are subjected

during the handling of cars. Impacts that

usually occur during switching operations can

be quite severe. Such impacts depend on the
122 AGRICULTURE HANDBOOK 2 5 2, U.S. DEPT. OF AGRICULTURE

coupling speed and vary as the square of that

speed. For example, the impact due to a speed

of 4 miles per hour is 16 times as great as the

impact due to a speed of 1 mile per hour. Similarly, at a speed of 8 miles per hour the impact

is 64 times as great as at 1 mile per hour.

Loading

Crates are carried in closed cars or in open cars

or flatcars. The selection of the proper freight

car depends on the object being shipped, the type

of crate, and the availability of cars. The waterproofness of boxcars may be very important with

many items of lading. Good flooring and side

sheathing are necessary when heavy blocking and

bracing must be fastened to them. Blocking

and bracing must be carefully done on flatcars

because, if fastenings give way, the crate may be

lost. Blocking and bracing will vary with the

container being shipped, especially in open cars,

and may consist of wood, wire, strapping, or

combinations of them. In any type of car the

crate should be properly placed or the item may

be injured even though it is properly packed. Not

only must the endwise movement of the car be

considered, but also the sidesway of the moving

train and the up-and-down movement of the car.

Sidesway and up-and-down movements occur

while the train is traveling, endwise movements

mainly during starting or stopping. The distribution of loads over the car must comply with the

rules of the transportation company.

Types oí Loads

Freight car loads are of two general types, floating and rigid. The floating load moves upon

impact. Since a slight movement is enough to

reduce the shock of impact, methods used for

floating loads may allow a slight movement

under high impacts. Rigid loads are usually

fastened so that no movement is apparent at

impact, through the use of blocking and bracing

well fastened to the floor or walls, tension straps,

or similar devices.

Floating loads.—Certain kinds of commodities,

such as diesel engines, lend themselves to a floating load, which can be either a single unit or a

number of units banded or wired together. Movement in the car is retarded by antiskid plates,

padding, or other means. Space is usually

allowed at the ends of the load for the anticipated

movement. A method has been developed for

placing plastic or rubber bags between the car

walls and containers. When the bags are inflated,

they provide the necessary cushioning.

A floating load is usually more desirable for

crates than a rigid load because it lessens the

shock to the item in the crate when the car is

started or stopped. Rigid fastening and blocking

develop high impact stresses because of the short

tmie required to stop. Any means of fastening

a load to allow some movement will result in lower

impact values because the stopping time has been

increased. Cushioning of light, delicate objects

has been given much study, but a great deal

remains to be done on devising methods for

lessening the impacts on heavy articles.

Rigid loads.—Rigid loads are often composed

of a number of smaller packs or a miscellaneous

assortment of containers that must be shipped in

a closed car. Rigid loads with blocking, bracing,

and strapping combinations are also used in open

cars for large crates and heavy equipment. The

location of bracing may depend on the load

height, the crate's center of gravity, its length

and width, and whether it can be wired or banded

to other loads.

Cross bracing is used extensively with rigid

loads in closed cars. When permissible, it should

be placed edgewise against the load because it is

stronger in this direction. K-bracing, a reinforcement of the cross bracing, is often used in

conjunction with it where stronger bracing is required. Diagonals of the K usually extend from

the center of the cross bracing to the car sides or

floor or both. The ends of the cross bracing or

diagonals must be held securely in place by blocks

nailed to the car floor or walls to form pockets.

Where possible, parts of this blocking should be

nailed to an upright strut in the car sides or to a

stringer in the floor even if it is necessary to use a

longer block.

Center bracing is used as a width filler between

containers located along the sides of the car.

Floor blocking is used along the floor to keep

the load from sliding and is generally reinforced

with backup cleats fastened to the floor.

An area of the sheathing in the car is sometimes

covered Avith wall reinforcing planking nailed to

the side frame members. This allows better

nailing of the blocking used for cross or K-bracing.

Some tall loads may require blocking or anchoring at the top also. This is especially true of

high crates or double-decked containers shipped

in open cars.

Various kinds of bulkheads are used to hold

loads in place, to divide them into sections, or to

protect the doors of the cars when loads extend

into the door area. The construction of the bulkheads varies with the weights of the loads. Bulkheads should be held in place by blocking and

bracing or by metal straps anchored to the wall.

Metal strapping allows some resiliency and consequently some cushioning resistance to impacts.

Well-anchored strapping may require the use of

some trussing between the strap and the load to

distribute the pressure more uniformly. These

straps should be extended along the side of the

car so that tension is at right angles to the fastenings that hold the anchor plates.

The most common deficiency in car bracing is

the use of too few nails. When possible, nailing
WOOD CRATE DESIGN MANUAL 123

should be arranged to be under lateral displacement rather than in direct withdrawal. Nails

should be driven straight into floors through the

blocking, rather than diagonally through the

sloping faces of the blocking.

SHIPPING LOSSES AND INSURANCE

Under normal conditions of domestic rail

shipments, material loaded in open cars is

inspected by railroad representatives before the

car is moved and the railroad assumes responsibiUty. In closed cars, however, the Association

of American Railroads rules are not mandatory

and are used only for guidance. Closed cars

are not ordinarily inspected, but if damage

occurs to the contents, they are inspected at

the destination to determine the cause before a

settlement is made.

Export shipping companies are specifically

exempt from most forms of liabilities under the

laws of many countries. The exceptions to this

usually include loss or damage due to negligence

in proper loading, custody, or delivery of the goods.

The shipper or consignee must assume responsibility for all remaining risks during the shipment.

To prevent loss to the shipper, a form of marine

insurance covers these losses. Marine insurance

may be obtained to cover such perils as pilferage,

theft, and leakage, as well as loss or damage if

the ship should sink, burn, or be involved in a

collision. However, the more hazards covered by

the policy the higher the rate, so it is not

economical to pay for broader protection than is

actually required.

Rates in marine insurance are rather complex

and are not fixed. They depend, among other

things, on the type of vessel, the route, the perils

insured against, the type of packing used, and the

loss record of the shipper. This latter factor,

of course, reflects the type of container and the

method of blocking and bracing used by the

shipper, because well-constructed and well-packed

crates will normally receive little damage diu-ing

the voyage. A shipper who uses adequate containers pays lower rates. Underwriters keep

statistical records of shippers they deal with and

allow lower rates for those with good records.

TARE WEIGHT OF CRATES

In assembling crates it is necessary to have

a reasonably close estimate of the tare weight in

order to properly compute the number and kind of

fastenings needed. The number of fastenings

required to secure the sides and ends of the crate

to the base is ordinarily computed for the gross

weight—weight of the contents plus the tare

weight.

If a bill of material has been made, the tare

weight can be found by multiplying the number

of board feet of lumber in the crate by the weight

per board foot for the kind and moisture content

of the lumber used. An average figure, if species

are not known, is 2,350 pounds per thousand

board feet.

It is often desirable to know the tare weight

before a bill of material is made. Any short

method for estimating tare weights will depend

not only on the type of crate but also on its width

and height. Normally, wide crates and high

crates require larger members than narrower or

shallower crates.

The factors in table 36 for estimating the tare

weight of crates are based on an average density

and moisture content. The weights are based on

a value of 2,350 pounds for a thousand board feet

of lumber. If woods are denser than average, or

have a higher moisture content, a slightly increased weight might be used. A slightly decreased

weight might also be somewhat more accurate if

the wood is less dense and quite dry. When more

than one kind of wood is used some interpolation

may be necessary, depending upon the different

densities and moisture contents.

The following method will give a reasonably

close estimate of tare weights of military-type

sheathed crates. The construction of this type of

crate is covered in the chapter on sheathed crates.

In these estimations the total area in square feet

must be determined. This includes area of top,

base, ends, and sides. All dimensions should be

figuredi to the nearest foot or half foot. Multiply

this total area (A) by the factors listed in table 36

to find the tare weight in pounds.

Use the following procedure:

Step 1—Determine area of one end, ä

Step 2—Determine total area of crate, A

Step 3—In table 36 select the appropriate line

of S values and the colmnn of member sizes. Then multiply crate

area by the factor given.

Example:

A lumber-sheathed crate with 1-inch frame

members is 10 feet long and 6 feet in width

and height.

The end area S equals 6X6 =36 square feet

The total siu-face area A equals:

2X6X10 = 120 (top and base)

2X6X10=120 (two sides)

2X6X6=72 (two ends)

Â=312 square feet

Then in the first column of table 36 the end area,

36 square feet, is between 20 and 40. Under

lumber sheathing with 1-inch frame members, A is

to be multiphed by 4.5.

Tare weight is then 312X4.5 or 1,404 pounds.
124 AGRICULTURE HANDBOOK 2 5 2, U.S. DEPT. OF AGRICULTURE

TABLE 36.—Method of estimating tare vxnght of military-type sheathed crates

S

(end area)

Weight of crate

1-inch

lumber sheathing

2-inch

framing

members

1-inch

framing

members

%-inch

plywood sheathing

2-inch

framing

members

1-inch

framing

members

Sq. ft

Less than 20_

Over 20 less than 40

Over 40 less than 70

Over 70

Lb.

A X 4.0

A X 5.0

A X 6.0

A X 7.0

Lb.

A X 3.6

A X 4.5

A X 5.4

A X 6.3

Lb.

X 3.2

X 4.0

X 4.8

X 5.6

Lb.

Ax 2.9

A X 3.6

A X 4.3

Ax 5.0
APPENDIX III. GLOSSARY

Air-dried.—See Seasoning.

Annual growth ring.—See Ring, annual growth.

Beam.—A structural member transversely supporting a load.

Beams and stringers.—Large pieces (nominal

dimensions 5 by 8 inches and up) of rectangular

cross section, graded with respect to their strength

in bending when loaded on the narrow face.

Blemish.—A marring of the appearance of

wood, not necessarily a defect.

Blue stain.—See Stain, blue.

Boards.—See Lumber.

Bow.—Distortion of a board in which the

face is convex or concave longitudinally.

Brashness.—A condition that causes some

pieces of wood to have low resistance to shock

and to fail abruptly across the grain without

splintering when broken in bending.

Broad-leaved trees.—See Hardwoods.

Brown stain—See Stain, brown.

Cell.—A general term for a minute unit of

wood structure. Fibers, vessel segments, and

other elements of diverse structure and function

are cells making up fibrous and porous tissues

in the wood structure.

Check.—A lengthwise separation of wood,

the greater part of which occurs across the rings

of annual growth.

Chemical brown stain.—See Stain, chemical

brown.

Column.—A structural compression member,

usually vertical, supporting loads acting on or

near and in the direction of its longitudinal axis.

Conifer.—See Softwoods.

Crook.—Distortion of a board in which the

edge is convex or concave longitudinally.

Crossband.—To place the grain of layers of

wood at right angles in order to minimize shrinking and swelling and consequent warping; also

a layer of veneer at right angles to the face plies.

Cross grain.—See Grain.

Cup.—Distortion of a board in which the

face is convex or concave transversely.

Decay.—Disintegration of wood substance

through the action of wood-destroying fungi.

Incipient decay.—The early stage of decay

in which the disintegration has not proceeded far enough to soften or otherwise

perceptibly impair the wood.

Typical or advanced decay.—The stage

of decay in which the disintegration is easily

recognized because the wood has become

punky, soft and spongy, stringy, pitted,

or crumbly.

Defect.—Any irregularity in or on wood that

may lower its strength.

Density.—The mass of a body per unit volume.

When expressed in the metric system, it is numerically equal to the specific gravity of the same

substance.

Diagonals.—Angle members placed between

vertical and horizontal members within a panel

to provide rigidity to the crate. Struts and horizontal braces are so spaced that the angle of the

diagonal is as near 45"^ as possible. In open

crates diagonals are usually single; in lumbersheathed crates they are crossed in an ^^X^^ pattern.

Diamonding.—A distortion in drying that causes

a piece of wood originally rectangular or square

in cross section to become diamond-shaped.

Dimension.—See Lumber.

Dimension stock.—Squares or flat stock, usually

in pieces under the minimum sizes admitted in

standard lumber grades, rough or dressed, green

or dry, cut to the approximate dimensions required for the various products of woodworking

factories

Dunnage.—In crates, blocking or timbers placed

on the top of large crates to distribute the load

evenly.

Durability.—A general term for permanence or

lastingness. Frequently refers to the degree of

resistance of a species or of an individual piece

of wood to attack by wood-destroying fungi under

conditions that favor such attack. In this connection the term resistance to decay is more specific.

Edge grain.—See Grain.

End frame members.—See Frame members.

Encased knot.—See Knot.

Equilibrium moisture content.—The moisture

content at which wood neither gains nor loses

moisture when surrounded by air at a given relative humidity and temperature.

Fiber.—A wood fiber is a comparatively long

(one-twenty-fifth or less to one-third inch),

narrow, tapering cell closed at both ends.

Fiber-saturation point.—The stage in the drying

or in the wetting of wood at which the cell walls

are saturated and the cell cavities are free from

water. Usually taken as approximately 30 percent moisture content.

Filler strips.—Narrow strips of lumber used to

fill in spaces between load-bearing members of

the base so that the lower frame members of the

sides have uniform bearing along their entire

length.

Flat grain.—See Grain.

125
126 AGRICULTURE HANDBOOK 2 5 2, U.S. DEPT. OF AGRICULTURE

Floorboards.—Sheathing for the base. Fastened to the skids ; when used to support concentrated loads, called load-bearing floorboards because

they transfer the load to the edge skids.

Frame members.—Parts that form the fundamental structure of both sheathed and open crates.

Strength and rigidity of the open crate depend

entirely on these members and their fastenings.

End frame members.—Edge crosswise framing members of the top, located at each end

of the panel.

Intermediate members.—-Lengthwise frame

members of the top, located between the side

frame members. They help to resist shock,

and the top sheathing is naüed to them.

Side fram£ memiers.—'Edge framing members of a top without a joist, parallel to the

length in sheathed crates. In open crates

they may be called longitudinal members.

Side frame members tie the framework together and may also serve as fastening members for assembly.

Upper and Imver frame members.—Horizontal members at the top and bottom of the

side and end panels. In both open and

sheathed crates they frame the panels.

Grain.—The direction, size, arrangement, appearance, or quality of the fibers in wood.

Close-grained ivood.—Wood with narrow

and inconspicuous annual rings. The term is

sometimes used to designate wood having

small and closely spaced pores, but in this

sense the term^n^ textured is more often used.

Coarse-grained v:ood,—Wood with wide and

conspicuous annual rings in which there is

considerable difference between springwood

and sunmierwood. The term is sometimes

used to designate wood with large pores, such

as oak, ash, chestnut, and walnut, but in this

sense the ieim coarse texturedismore often used.

Cross grain.—Fibers not parallel with the

axis of a piece. May be either diagonal or

spiral grain or a combination of the two.

Diagonal grain.—Annual rings at an angle

with the longitudinal axis of a piece.

Edge grain.—Edge-gvhin Imnber has been

sawed parallel with the pith of the log and

approximately at right angles to the growth

rings; the rings form an angle of 45° or more

with the surface of the piece.

Flat grain.—Flat-grain lumber has been

sawed parallel with the pith of the log and

approximately tangent to the growth rings;

the rmgs form an angle of less than 45° with

the surface of the piece.

Interlocked-grain iDood.~\Nooà in which the

fibers are inclined in one direction in a number

of rmgs of annual growth, then gradually

reverse and are inchned in an opposite direction m succeeding growth rings, then reverse

Open-grained wood.—Common painters'

classification for woods with large pores, such

as oak, ash, chestnut, and walnut. Also

known as coarse textured.

Plain-sawed.—Another term for flat grain.

Quarter-sawed.—Another term for edge

grain.

Spiral grain.—A type of growth in which

the fibers take a spiral course about the bole

of a tree instead of the normal vertical course.

The spiral may extend right-handed or lefthanded around the tree trunk.

Vertical grain.—Another term for edge grain.

Green wood.—Unseasoned, wet wood.

Growth ring.—See Ring, annual growth.

Hardwoods.—The botanical group of trees that

are broadleaved. The term has no reference to

the actual hardness of the wood. Angiosperms

is the botanical name for hardwoods.

Headers.—End cross members of the base.

Headers are bolted to the skids and act as fastening

members for assembly of the end panels. They

may also be used as reinforcing to resist forklift

handling stresses at the ends.

Heart, Heartwood.—The wood extending from

the pith to the sapwood. Its cells no longer

participate in the life processes of the tree.

Heartwood may be infiltrated with gums, resins,

and other materials which usually make it darker

and more decay-resistant than sapwood.

Horizontal braces.—Members ordinarily used

in side and end panels of higher crates to reduce

the unsupported span or height of the panels

and increase crate rigidity. They are placed in

the horizontal position between the upper and

lower frame members.

Inspection doors and ports.—Small openings

built into the end panel to provide access for

inspection of the contents. They can be locked

or sealed.

Intermediate members.—See Frame members.

Joists.—Load-supporting members of the top,

spanning the width of the crate. They transfer

loads to the sides and prevent the top from being

crushed when the crate is handled with slings

or grabhooks.

Joist supports, vertical.—Members fastened to

the inside face of the side panels of sheathed

crates to support the ends of the joists.

Kiln-dried.—See Seasoning.

Knot.—Part of a branch or limb that has

become incorportated in the body of a tree.

Decayed knot.—A knot which, due to

advanced decay, is not so hard as the surrounding wood.

Encased knot—A knot whose rings of

annual growth are not intergrown with those

of the surrounding wood.

Intergrown knot.—A knot whose rings of

annual growth are completely intergrown

with those of the siurounding wood.
WOOD CRATE DESIGN MANUAL 127

Round knot.—A knot whose sawn section

is oval or circular.

Sound knot.—A knot that is solid across

its face and as hard as the surrounding wood.

Spike knot,—A knot sawn lengthwise.

Lag screw-reinforcing strap.—Prepunched

strapping of annealed steel. It is nailed to the

inside of the sheathing at the bottom fastening

areas of the side and end panels of demountable

crates. It reinforces the sheathing and increases

the lateral-withdrawal resistance of the assembly

lag screws.

Laminated wood.—A piece of wood built up

of phes or laminations that have been joined with

either glue or mechanical fastenings. The term

is most frequently applied if the plies are too

thick to be classified as veneer and the grain of all

plies is parallel.

Liner.—Asphalt-impregnated or laminated

paper or similar material, used in the sides, ends,

and sometimes the tops of lumber-sheathed crates

to keep moisture out.

Lower frame members.—See Frame members.

Lumber.—The product of the saw and planing

mill not further manufactured than by sawing,

resawing, and passing lengthwise through a standard planing machine, crosscut to length, and

matched.

Dressed size.—The dimensions of lumber

after shrinking from the green dimension and

being planed, usually % inch less than the

nominal or rough size. For example, a 2 by 4

strut actually measures 1% by 3/8 inches. See

Lumber, Nominal size.

Factory and shop lumber.—^Lumber intended

for further manufacture. It is graded on the

basis of the percentage of the area from which

a limited number of cuttings of a specified or

minimum size and quality can be made.

Matched lumber.—Lumber dressed and

shaped to make close tongue-and-gxoove joints

at the edges or ends when laid edge to edge or

end to end.

Nominal size.—As applied to timber or

lumber, the rough-sawn commercial size by

which it is known and sold in the market.

See Lumber, Dressed size.

Rough lumber.—Lumber as it comes from

the saw.

Surfaced lumber.—Lumber that has been

dressed by running it through a planer.

Yard lumber.—Lumber less than 5 inches

thick intended for general building purposes.

Board.—Yard Imnber less than 2 inches

thick, 1 inch or more in width.

Dimension.—All yard lumber except boards,

strips, and timbers (yard lumber at least 2

inches but less than 5 inches thick, of any

width).

Strip.—Yard lumber less than 2 inches

thick and less than 4 inches wide.

692-318 0—64 9

Moisture content of wood.—Weight of the

water contained in the wood, usually expressed in

percentage of weight of the ovendry wood.

Pitch pocket.—An opening between or within

annual growth layers in softwoods usually containing, or which has contained, pitch, either sohd

or liquid.

Pith.—The small soft core in the structural

center of a log.

Piain-sawed.—See Grain.

Plywood.—Three or more layers of veneer

joined with glue, usually with the grain of adjoining plies at right angles. Almost always an odd

number of plies is used for balanced construction.

Preservative.—Any substance that, when suitabl}^ applied to wood, makes it resistant to wooddestroying fungi, borers of various kinds, and

similar destructive life for a reasonable length of

time.

Quarter-sawed.—See Grain.

Radial.—Coincide it with a radius from the

axis of the tree or log to the circumference.

Ring, annual growth.—The growth layer put on

in a single growth year, including springwood and

summerwood.

Rotary-cut veneer.—See Veneer.

Rubbing strips.—Strips of wood, usually 2

inches thick, nailed to the underside of each skid

as spacers to allow sling lifting of the crate from

the ends and forklift handling from the sides.

Sapwood.—The wood next to the bark, usually

of lighter color than the heartwood, one-half inch

to 3 or more inches wide, actively involved in the

life processes of the tree. Under most conditions

sapwood is more susceptible to decay than heartwood and as a rule, more permeable to liquids.

Sapwood essentially is neither weaker nor stronger

than heartwood.

Sawed veneer.—See Veneer.

Seasoning.—Removing moisture from green

wood in order to improve serviceability.

Air-dried or air-seasoned.—Dried by exposure to the air, usually in a lumberyard,

without artificial heat.

Kiln-dried.—Dried in a kiln with artificial

heat.

Shake.—A separation along the grain, the greater part of which is between the rings of annual

growth.

Sheathing.—The covering, usually of boards or

plywood, placed over the frame of a crate. It

serves to tie the frame members into a panel and

aids the diagonals and struts of the sides and ends

in supporting superimposed loads.

Sheathing paper.—A liner material used to keep

moisture out.

Side frame members.—See Frame members.

Sills.—The members that, along with the sill

bridging, form the framework of sill-type bases.

Sills carry loads and transfer them to side panels

and serve as fastening members.
128 AGRICULTURE HANDBOOK 2 5 2, U.S. DEPT. OF AGRICULTURE

Sill bridging.—Members of the same depth as

the sills, inserted at right angles to the intermediate sills to prevent the sills from turning or

buckling.

Skids.—Lengthwise members of the base.

They help to support the load and serve as fastening members for flooring, headers, and the side

panels.

Sliced veneer.—See Veneer.

Softwoods.—The botanical group of trees that

have needle or scaleHke leaves and, except for

cypress, larch, and tamarack, are evergreen.

The term has no reference to the actual hardness

of the wood. Softwoods are often referred to

as conifers, and botanically they are called

gymnosperms.

Span.—The distance between supports, such as

structural members.

Specific gravity.—The ratio of the weight of a

body to the weight of an equal volume of water at

some standard temperature.

Springwood.—The part of the annual growth

ring formed early in the season's growth. It is

usually less dense and mechanically weaker than

summerwood.

Stain, blue.—A bluish or grayish discoloration

of the sapwood caused by the growth of certain

moldlike fungi on the surface and in the interior,

made possible by the same conditions that favor

the growth of other fungi.

Stain, brown.—A rich brown to deep chocolatebrown discoloration of the sapwood in some pines

caused by a fungus that acts similarly to the bluestain fungus.

Stain, chemical brown.—A discoloration of wood

that sometimes occurs in several species during air

or kiln drying, apparently caused by the oxidation

of extractives.

Strength.—The term in its broader- sense embraces all the properties of wood that enable it to

resist forces or loads. In its more restricted sense

it may apply to any one of the mechanical properties, and the name of the property should be stated,

as strength in compression parallel to the grain,

strength in bending, etc.

Structural timber.—Wood of relatively large size

for which strength is the controlling element in

selection and use.

Struts.—Frame members placed vertically between upper and lower frame members.

Summerwood.—The part of the annual growth

ring formed during the latter part of the yearly

growth period. It is usually more dense and

mechanically stronger than springwood.

Tangential.—Strictly, coincident with a tangent

at the circumference of a tree or a log, or parallel

to such a tangent. In practice, however, it often

means roughly coincident with a growth ring.

Tare weight.—Weight of the container itself, as

well as the blocking, bracing, and cushioning.

Twist.—A distortion caused by the turning or

winding of the edges of a board so that the four

corners of any face are no longer in the same plane.

Upper frame members.—See Frame members.

Veneer.—Thin sheet of wood.

Rotary-cut veneer,—Veneer cut in a continuous strip in a lathe by rotating a log

against the edge of a knife.

Sawed veneer.—Veneer produced by sawing.

Sliced veneer.—Veneer cut by moving a log,

bolt, or flitch against a knife.

Vertical joist supports.—See Joist supports,

vertical.

Vertical grain.—See Grain.

Wane.—Bark or lack of wood from any cause

on the edge or corner of a piece of lumber.

Warp.—Any variation from a true or plane surface. Warp includes bow, crook, cup, and twist.

Weathering.—The mechanical or chemical disintegration and discoloration of the surface of wood

caused by exposure to light, the action of dust and

sand carried by winds, and the alternate swelling

and shrinking of the surface fibers as they gain and

lose moisture during changes in the weather.

Weathering does not include decay.

Wood preservative.—See Preservative.

Workability.—The degree of ease with which

wood can be cut or shaped with hand or machine

tools, and the smoothness of cut obtainable.

Yard lumber.—See Lumber.
INDEX

Adhesives, use of, 13, 22

Advantages of good design,1

Anchoring crates, 121

Assembly :

general, 13

open crates, 53, 60

sheathed crates, 43, 45, 48

Balance point, 120

Base construction:

general, 2, 29

open crates, 51, 53, 59

sheathed crates, 32, 45, 46

Basic stresses, 10

Bill of lading, 120

Bill of material, 123

Blocking and bracing, 122

Bolts, 21

Bridging, 35

Bulkheads, 122

Cable handling, 76

Car impacts, 121

Carloading crates, 121

Cautionary marks, 120

Center bracing, 122

Center of balance, 120

Checks and splits, 10

Columns :

intermediate, 27

long, 28

short, 27

Compression members, 27

Connectors, 21

Contents,2

Cornerwise drop test, 79

Costs,4

Crates (general):

construction,1

contents,2

costs,4

definition,1

design, 2, 23

dimensions, 2,4

handling hazards,2

importance,1

open, 4, 50

requirements,2

selection, 2,4

sheathed, 4, 32

storage conditions,4

transportation,2

weight,4

Cross bracing, 122

Decay, 10

Demountability, 2, 19, 21, 22

Design, 1, 2, 23

Design principles, 24

Destination,2

Diagonals :

importance, 24

strength, 12

Disassembly,2

Displacement,4

Drop tests, 78

Dunnage, 31, 74, 76

Duration of load,9

Edgewise drop test, 78

Effective span, 24

End construction:

open crates, 51, 53, 60

sheathed crates, 39, 45, 46

End struts, 37

Euler formula, 27, 28

Exports, 121

Fabrication:

general, 13, 18

open crates, 51, 53, 59

sheathed crates, 32, 45, 46

Fastenings :

adhesives, 22

bolts, 21

lag screws, 19

nails, 13

steel strapping, 22

timber connectors, 21

wood screws, 22

Floating loads, 122

Floor blocking, 122

Floorboards, 9, 30, 73

Flexure formula, 29

Forklift:

handling, 78

headers, 29

Frame members, 28

Framing test, 74

Freight classification, 121

Glues, 22

Grabhooks:

damage,3

handling, 78

reinforcing joist, 31, 43

Grain, slope of,9

Handling:

hazards, 2,3

tests, 76

Headers, 29, 35

Identification marks, 120

Impact loading, 10

Insect attack, 10

129
130 INDEX

Intermediate columns, 27

Intermediate sills, 30, 34

Joists, 9, 31, 41

Knots, 9, 10

Lag screws, 19

Light-duty type :

open, 59

sheathed, 46

Like-on-like loading, 4, 31

Limited-military type:

open, 53

sheathed, 45

Loading in cars, 122

Loads:

floating, 122

general, 29

rigid, 122

top testing, 76

Long columns, 28

Longtime loading, 11

Lumber sizes, 11

Marine insurance, 123

Marking crates, 120

Materials for crates:

costs,4

fastenings, 13

paper overlay, 13

plywood, 11

w^ood,5

Members:

compression, 27

cross, 29

determining size of, 27

tension, 27

Military type:

open, 50

sheathed, 32

Modulus of elasticity, 27

Moisture content, 9, 10, 15

Moment:

maximum bending, 29

of inertia, 29

Nailing patterns, 18

Nails :

calculating nail-holding capacity, 14

clinching, 16

direction of driving, 15

penetration, 15

points and heads, 15

rules for use, 17

sizes, 13, 15

surface condition, 15

types, 13

Open crates:

general, 1, 4, 50

light-duty, 59

limited-military, 53

military type, 50

Packing lists, 120

Panel member sizes, 52, 80

Paper-overlaid veneer, 13

Partial disassembly,2

Pendulum impact test, 74, 79

Plywood, 11

Racking resistance,3

Reduction factors, 11

Rigid loads, 122

Rough-handling tests, 74

Rubbing strips, 35, 76

Screws, 22

Section modulus, 29

Shakes, 10

Sheathed crates:

general, 1, 4, 32

light-duty, 46

limited-military type, 45

military type, 32

Sheathing thickness, 27

Shipment, 2, 32, 50, 120

Shipping loss:

insurance, 123

prevention, 121

Short columns, 27

Shrinkage,6

Side construction:

open crates, 51, 53, 59

sheathed crates, 37, 45, 46

Sills, 29, 30, 35

Skid assemblies, 68

Skids, 24, 29

Slenderness ratio, 27

Sling handling, 3, 76, 120

Slope of grain, 9, 10

Species of w^ood,5

Specific gravity,6

Splicing, 35

Splits, 10

Stacking, 4, 31

Stain, 10

Storage conditions,4

Strapping, 22, 122

Stress diagram, 26

Struts, 28

StyleA and A-1 open crate, 52

StyleB open crate, 52

StyleC open crate, 54

Superimposed load tests, 74

Tare weight, 123

Tension members, 27

Testing crates:

drop, 78

general, 73

handling, 76

impact, 79

superimposed-load, 74

Timber connectors, 21

Timber truss, 26

Top construction:

general, 31

open crates, 53, 60

sheathed crates, 41, 45, 46

Top load tests, 74, 75
INDEX 131

Truss diagram, 26

Types of loads, 122

Ventilation, sheathed crate, 40

Wane, 10

Warping, 10

Weather conditions, 2, 4, 41, 50

Weight-length value, 68

Withdrawal resistance:

lag screws, 19

nails, 16

Wood:

blue stain, 10

checks and splits, 10

decay, 10

density, 5, 15

Wool—Continued

duration of load, 9

insect attack, 10

knots, 9

moisture content, 5, 9, 15

shakes, 10

slope of grain, 9

strength, 5

wane, 10

warping, 10

Wood species:

properties, 6

strength and variability, 5, 10, 15

weight, 5

Working stresses, 10

U, S. GOVERNMENT PRINTING OFFICE : 1964 O - 692-318