California Code of Regulations › Title 8 - Industrial Relations › Division 1 - Department of Industrial Relations › Chapter 4 - Division of Industrial Safety › Subchapter 13 - Logging and Sawmill Safety Orders › Appendix B - Engineering Data

Current through Register 2024 Notice Reg. No. 28, July 12, 2024
Strength and Weights of Wire Ropes
Rope Diameter in
							 Inches
Breaking Strength Plow Steel in Tons 6x 19 6
							 x17 6 x 21
Weight Per Foot in Pounds
¼ ..........................
2.39
.10
5/16
							 ..........................
3.71
.16
3/8 ..........................
5.31
.23
7/16
							 ..........................
7.19
.31
.......................... ½
9.35
.40
9/16
							 ..........................
11.8
.51
5/8
							 ..........................
14.5
.63
¾
							 ..........................
20.7
.90
7/8
							 ..........................
28.0
1.2
1
							 ..........................
36.4
1.60
1 1/8
							 ..........................
45.7
2.03
1 ¼
							 ..........................
56.2
2.50
1 3/8
							 ..........................
67.5
3.03
1 ½
							 ..........................
80.0
3.60
1 5/8
							 ..........................
93.4
4.23
1 ¾
							 ..........................
108.0
4.90
1 7/8
							 ..........................
123.0
5.63
2
							 ..........................
39.0
6.40
2 1/8
							 ..........................
156.0
7.23
2 ¼
							 ..........................
174.0
8.10
2 ½
							 ..........................
212.0
10.00
2 ¾
							 ..........................
254.0
12.10
3
							 ..........................
300.0
15.00
When ropes are galvanized deduct 10 percent from the above
					 listed strengths. When wire strand centers and independent wire rope centers
					 are used add 7 ½ percent to strengths.
Common Causes of Wire Rope Failure
1. Ropes of incorrect size, construction, or grade
2. Ropes allowed to drag over obstacles
3. Ropes not properly lubricated
4. Ropes operating over sheaves and drums of inadequate
					 size
5. Ropes overwinding or crosswinding on drums
6. Ropes operating over sheaves and drums out of
					 alignment
7. Ropes operating over sheaves and drums with improperly
					 fitting groves or broken flanges.
8. Ropes permitted to jump sheaves
9. Ropes subjected to moisture of acid fumes and salt
					 air
10. Ropes with improperly attached fittings
11. Ropes permitted to untwist
12. Ropes subjected to excessive heat
13. Ropes kinked
14. Ropes subjected to severe overloads due to inefficient
					 operation
15. Ropes destroyed by internal wear caused by grit
					 penetrating between strands and wires.
Rules for Discarding Wire Ropes
1. Safety factors must never fall below 4.5
2. Ropes of standard construction shall be discarded where
					 there are 6 broken wires in 1 rope lay
3. When wires on crown are worn to 65 percent of their
					 original diameter
4. When there are more than 8 broken wires reduced by wear
					 more than 80 percent in cross-section
5. When marked corrosion appears When a new rope is
					 installed, there is a short period (while the rope is taking its set and
					 equalizing tension) during which breaks are relatively frequent. These breaks
					 do not necessarily indicate that the rope is wearing out or that it is
					 overstressed. After the period of their occurrence, the rope will run for
					 sometime without more wires breaking. Toward the end of the life of the rope,
					 however, it may happen that the number of breaks begins to increase rapidly.
					 This condition is a sign that the rope is going to pieces and it should be
					 taken off immediately. It is recommended, therefore, that not only should rope
					 inspections be frequent, but that the number of broken wires be recorded so
					 that the increase in breaking rate may be ascertained.
STRENGTH EFFICIENCY UNDER STATIC LOAD
Sheave
							 Diameter
Efficiency of Rope
10 times rope
							 diameter..........................
.......................... 79% of
							 strength of straight rope
12 times rope diameter..........................
.......................... 81% of strength of straight rope
14 times rope diameter..........................
.......................... 86% of strength of straight rope
16 times rope diameter..........................
.......................... 88% of strength of straight rope
18 times rope diameter..........................
.......................... 90% of strength of straight rope
20 times rope diameter
							 ..........................
.......................... 91% of strength
							 of straight rope
24 times rope
							 diameter..........................
.......................... 93% of
							 strength of straight rope
30 times rope diameter..........................
.......................... 95% of strength of straight rope
EXAMPLE: Given a 1-inch rope (breaking strength 36.4 tons)
					 reeved through a 10-inch pulley. The strength of the rope is (36.4) (.79) =
					 28.75 tons. (Based on U.S. Bureau of Standards tests.)
APPLICATION OF CLIPS
Diameter of
							 Rope
..........................
Number of Clips
Space
							 Between Clips
1 ½
inch...........................................................
..........................
							 8
10 inches
1 3/8
inch...........................................................
..........................
							 7
9 inches
1 ¼
inch...........................................................
..........................
							 6
8 inches
1 1/8
inch...........................................................
..........................
							 5
7 inches
1
inch...........................................................
..........................
							 5
6 inches
7/8
inch...........................................................
..........................
							 5
5 ½ inches
¾
inch...........................................................
..........................
							 5
4 ½ inches
3/8- 5/8
inch...........................................................
..........................
							 4
3 inches
Proper number ad spacing to develop 80 percent of rope
					 strength.
EFFECTIVENESS OF GUYS ACCORDING TO
					 ANGLE
Guys making angle with the horizontal greater than 60 will
					 be considered less than 50% effective.
Degree
Effectiveness
60° to 45°..........................
.......................... 50% to 75%
45° to 30°..........................
.......................... 75% to 85%
30° to 10°
							 ..........................
.......................... 85% to 95%
EFFECTIVENESS OF GUYS ACCORDING TO NUMBER AND
					 SPACING
No. Guys Equally
							 Spaced
Guys Most Effective When Pull
							 Is
Guys Will Support Strain Equal to
							 Following
3
Opposite 1 guy
100% of strength of
							 one guy
4
Halfway between 2 guys
140% of
							 strength of one guy
5
Opposite 1 guy or halfway between 2
							 guys
160% of strength of one guy
6
Opposite 1 guy or halfway between 2
							 guys
200% of strength of one guy
7
Opposite 1 guy or halfway between 2
							 guys
225% of strength of one guy
8
Halfway between 2 guys
260% of
							 strength of one guy
9
Opposite 1 guy or halfway between 2
							 guys
290% of strength of one guy
10
Opposite 1 guy or halfway between 2
							 guys
325% of strength of one guy
LENGTH OF GUYS REQUIRED FOR VARIOUS ANGLES OF
					 EFFICIENCY
The following table will furnish the answers to the
					 following problems which usually arise when making up guy lines.
(1) What length of line is needed to reach from a certain
					 height to the ground with the required angle of efficiency?
(2) If the guylines are already cut and the required angle
					 of efficiency is known, how high above the ground can the guys be
					 rigged?
(3) If you know how high the guys are to be rigged above
					 the ground, the length of guys and the angle of efficiency needed, how far away
					 from the base of the spar or mast should stumps be selected or "deadmen" be
					 placed to hold the guys?
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No. of Guys
Guys
							 Most Effective When Pull Is
Guys Will Support Lead
							 Equal to:
8
Halfway between 2 guys
260% of
							 strength of 1 guy
9
Either halfway between 2, or opposite 1
							 guy
290% of strength of 1 guy
EXAMPLE: In lifting a 10-ton log between spreader bar
					 rigger spar poles the horizontal force at the top of the pole is found to be 25
					 tons. Using a factor of safety of 5 the design strength of 1 ½ -inch
					 guys is
80.0
= 16 tons. If the spar pole guys are
							 rigged at 80 angle with the ground, they are 85% effective (see table). How
							 many guys should be used?
5
25
=
1.84 or 184%
(16)
(.85)
The number of guys needed to support 184% of strength of 1
					 guy in between 5 and 6 (see table). Therefore, 6 guys should be used with 1
					 ½ -inch cable. Other cable sizes will give a variety of numbers of guys
					 for more practicable application.
INDIRECT METHOD OF DETERMINING THE LOAD ON A WIRE
					 ROPE.
Since 1 horsepower is the rate at which 550 foot-pounds of
					 work are done per second, the horsepower exerted by an engine on a rope may be
					 expressed:
HP =
feet x
							 pounds
seconds x 550
By rearrangement:
Pull on rope in pounds =
horsepower x seconds x 550
feet
Thus if you know the horsepower of a given engine and
					 measure the number of seconds it takes a point on the rope to go a given
					 distance the pull on the rope may be found.
EXAMPLE: A 100-HP gasoline donkey engine requires 10
					 seconds to reel in 30 feet of cable when working at nearly wide-open throttle.
					 What is the pull on the cable?
Since 100 HP is the ideal SAE rating of a stripped engine
					 it is not a true indication of the power delivered at the cable. A good
					 assumption is 1/3 of rated horsepower.
Pull on rope in pounds = 33 x 10 x
							 550
___________________________
=
							 6,050 pounds
30
Providing a safety factor of 5 the required rope strength
					 should be 30,250 pounds or 15.2 tons. From the table on page 112, in Appendix
					 B, a 
					 5/8 -inch
					 cable is nearest to this strength.