NASA CASE NO.

PRINT FIG.

"i  ̧ ..' ,_

The invention disclosed in this document resulted from research in aeronautical and

space activities performed under programs of the National Aeronautics and Space

Administration. The invention is owned by NASA and is, therefore, available for

licensing in accordance with the NASA Patent Licensing Regulation (14 Code of

Federal Regulations 1245.2).

To encourage commercial utilization of NASA-owned inventions, it is NASA policy to

grant licenses to commercial concerns. Although NASA encourages nonexclusive

licensing to promote competition and achieve the widest possible utilization, NASA

will provide the necessary incentive to the licensee to achieve early practical

application of the invention.

Address inquiries and all applications for license for this invention to NASA Patent

Counsel, Langley Research Center, Code 143, Hampton, Virginia 23681-0001.

Serial No." 08/297,343

8/24/94 LaRC

(NASA-Case-LAR-14899-1) ADJUSTABLE

BIAS COLUMN END JOINT ASSEMBLY

Patent Application (NASA. Langley

Research Center) 16 p

G3/31

N95-14111

Unc]as

0029856

C:\WPWIN60\WPDOCS_STAR.NTS
LAR 14899-1 

AWARDS ABSTRACT 

ADJUSTABLE BIAS COLUMN END JOINT ASSEMBLY 

This invention is an improvement to mechanical end joint systems, and more 

particularly, to a mechanical end joint system useful for the transverse connection of 

numerous strut elements to a common node to permit the rapid assembly and 

disassembly of diverse skeletal framework elements. 

According to the present invention, an adjustable mechanical end joint system for 

connecting structural column elements eliminates the possibility of free movement 

between joint halves during loading or vibration. The end joint has a node joint body 

having a cylindrical engaging end and a column end body having a cylindrical engaging 

end. The column end joint body has a compressible preload mechanism and plunger 

means housed therein. The compressible preload mechanism may be adjusted from 

the exterior of the column end joint body through a port. 

Novel aspects of the present invention include providing a readily accessible external 

length adjustment to column end joint Belleville washer stacks, without requiring their 

individual disassembly. 

Inventor: Richard E. Wallsom Harold G. Bush 

Address: 104 Maid Marion Place 1 16 Three Point Court 

Williamsburg, VA 231 85 Yorktown, VA 23692 

Employer: LESC NASA LaRC 

Initial Evaluator: Donald R. Rummler 

Serial No.: 081297,343 

Filed: 8/24/94 
LAR 14899-1 -1-

ADJUSTABLE BIAS COLUMN END JOINT ASSEMBLY

Ori,qin of the Invention

PATENT APPLICATION

5 The invention described herein was made in performance of work

under a NASA contract and is subject to provisions of Section 305 of the

National Aeronautics and Space Act of 1958, as amended, Public Law

85-568 (72 Stat. 435; 42 USC 2457).

10 Back,qround of the Invention

.

m

Field of the Invention

15

This invention is an improvement to mechanical end joint systems, and

more particularly, to a mechanical end joint system useful for the transverse

connection of numerous strut elements to a common node to permit the rapid

assembly and disassembly of diverse skeletal framework elements.

20

25

3O

.

m Description of the Related Art

This invention answers an identified problem by overcoming the

shortcomings noted on Page 2 (lines 20 - 26), and Page 4 (lines 37 - 51), of

U.S. Patent 4,963,052, MECHANICAL END JOINT SYSTEM FOR

CONNECTING STRUCTURAL COLUMN ELEMENTS, the specification of

which is incorporated herein by reference.

A preload stress presses the components more tightly together to

effect a compressive fit, thereby eliminating the possibility of free movement

between the joint halves during loading or vibration.

Dimensions between the latch plunger and sliding latch bolt are critical

to the ease and reliability with which these end joint fastenings can be
LAR 14899-1 -2- PATENT APPLICATION

assembled by space-suited astronauts. A target torque range of 35-45 in.lb.

is deemed necessary for effective functioning. Component variations as

small as 0.01 inch resulted in operating torque variations as great as +10

in.lb, in column end joint assemblies due to tolerance accumulations among

5 the various component parts, which in turn affected the initial compression of

the Belleville washer stack. No way existed to adjust this torque after

assembly, requiring repeated assembly/test/disassembly cycles in the search

for a Belleville washer arrangement to meet the 35-45 in.lb, requirement. A

typical series of 6 cycles, at the cost of many skilled man-hours operating

10 expensive calibration equipment, was required to assemble an acceptable

joint. This process tended to damage threaded joint components.

Summary of the Invention

15

20

25

This invention provides a readily accessible external length adjustment

to column end joint Belleville washer stacks, without requiring their individual

disassembly. Quicker, more accurate, and more economical assembly of a

space-shuttle-borne component can be carried out.

The invention uses a threaded plunger to vary the pre-compression of

a Belleville washer stack. The plunger, being accessible following the

assembly of the column end joint, may thus be screwed "in" to increase the

compression, or "out" to reduce it. These actions in turn, either increase or

decrease the torque required to lock the joint assembly to it's mating

component.

Other objects and advantages of this invention will become apparent

hereinafter in the specification and drawings.
LAR 14899-1

Brief Description of the Drawin,qs

-3- PATENT APPLICATION

5

10

15

Figure 1 is a longitudinal section of the end joint assembly;

Figure 2 is a longitudinal section of the end joint assembly similar to

that in FIG. 1, but rotated 90 degrees about the axis thereof;

Figure 3 is an isolated detail of the plunger from FIG. 1, showing the

variable length plunger and Belleville washer stack;

Figure 4 shows the separate joint assemblies preparatory to contact.

Figure 5 is a lateral view of the end joint after both halves have initially

mated;

Figure 6 is a lateral view similar to Figure 5, after the operating ring

has been rotated the initial 20 degrees;

Figure 7 is a lateral view of the end joint with both halves fully mated,

after the operating ring has been rotated the final 25 degrees; and

Figure 8 is a developed view of the latch operating ring 8.

Description of the Preferred Embodiment

20

25

Referring now to FIG. 1, a longitudinal cross-section of the column end

joint body 4 is shown. In the illustrated embodiment, an internal latch

mechanism 18 is housed within the column end joint body. FIG. 3 shows the

internal latch mechanism, which comprises the latch bolt 19, preload

Belleville washer stack 32, Belleville washer pin 90, latch plunger 22, latch

retainer 28, and is held together with latch retainer screws 17. Access to the

Belleville washer pin 90 by a suitable allen wrench is via the wrench access

port 94.

The internal latch mechanism of FIG. 3 is slidably disposed within the

column end joint body 4, as shown in both FIGS. 1 & 2. A latch spring 30 is

located between latch retainer 28 and latch plug 34, allowing the latch bolt 19
LAR 14899-1 -4- PATENT APPLICATION

to deflect when a longitudinal force is applied against the inclined face

thereof.

Referring now to FIG. 2, another cross-sectional view of column end

joint body 4 along line 2-2 of FIG. 1 is shown. Latch pins 20 screw into latch

5 body 22 and serve as an internal race for needle roller bearings 24 and 26.

For the column end joint body 4 to mate with the node joint body 3 as

in FIGS. 5, 6 & 7, the transverse force on column end joint body 4 causes

sliding latch bolt 19 (FIGS. 1 and 2) to be pushed away from node joint body

3 until the longitudinal axes of the two joint halves become collinear, at which

10 point sliding latch bolt 19 is pushed against conical mating surface 70 by

latch spring 30, and the semicircular tongue 78 and groove 80 of the column

end joint body 4 mate with semicircular groove 82 and tongue 84 of the node

joint body 3, respectively.

To lock the joint and add a preload across the tongue and groove

15 faces, operating ring collar 6 is rotated 45 degrees so that the latch pins 20

are moved toward node joint body 3. Engagement of the halves 3 & 4 of the

end joint assembly depresses the latch bolt 18 against the spring 30,

resulting in a loose mating position connection between members.

For the complete joint assembly to be taken from the mate position to

20 the locked position, the operating ring 6 is rotated through 45 degrees. The

resultant latch pin movement causes a similar movement of latch plunger 22

of FIG. 2, which in turn causes preload Belleville washer stack 32 to

compress and exert an equal and opposite force on latch plunger 22 and

sliding latch bolt 19. The force imparted to sliding latch bolt 19 causes the

25 column end joint body 4 and node joint body 3 to be pressed more tightly

together, effecting a preload compressive fit, thereby eliminating the

possibility of free movement between the joint halves during loading or

vibration.

After initial mating, the operating ring 6 is rotated through

30 approximately 20 degrees to bring the outer pair of latch bolt bearings 26 to
5

10

15

20

25

LAR 14899-1 -5- PATENT APPLICATION

bear on operating cam 68 of FIG. 6, causing the latch bolt keeper screws 17

to unload. The load generated by the partially compressed Belleville

washers 32 is now reacted through the bearings 26 and the cam surfaces 78,

and across the conical mating surfaces 70 of the latch bolt 18 and the column

node joint 3.

During the final 25 degrees of operating ring 6 rotation (FIG. 7), the

Belleville washers 32 are compressed further, and roller bearings 26 finally

engage the cam detent 76. The end joint is now fully latched, with preload

forces from the Belleville washers 32, applied through the latch mechanism to

the mated semicircular faces 70 of the latch 18 and the column end joint body

3.

The mechanism allowing the external adjustment capacity embodied in

this invention is clearly seen in FIG. 3, where the Belleville washer pin 90,

and wrench access port 94 are evident. The external adjustment capacity

offered by this arrangement enables the major gains realized by this

invention.

Figure 8 is a developed view of the latch operating ring 8. The force

imparted to latch plunger 22 is transferred to the latch operating ring 8 by

means of outer needle roller bearings 26, which reached assembly position

free space 74 from unlatched bearing point 72 when the semicircular tongues

and grooves of FIG. 4 mated.

Referring to FIG. 8, in which a layout of the latch operating ring is

depicted, the outer needle roller bearings 26 first move from the open

position 72, thence into the assembly position free space 74, up the ramp 75,

and over the peak in the latch track until they lock into place in the locked

bearing point 76.

Although our invention has been illustrated and described with

reference to the preferred embodiment thereof, we wish to have it understood

that it is in no way limited to the details of such embodiment, but is capable of
LAR 14899-1 -6- PATENT APPLICATION

numerous modifications for many mechanisms, and is capable of numerous

modifications within the scope of the appended claims.
1

LAR 14899-1 _ PATENT APPLICATION

ADJUSTABLE BIAS COLUMN END JOINT ASSEMBLY

Abstract of the Disclosure

5 An adjustable mechanical end joint system for connecting structural

column elements and eliminating the possibility of free movement between

joint halves during loading or vibration has a node joint body having a

cylindrical engaging end and a column end body having a cylindrical

engaging end. The column end joint body has a compressible preload

10 mechanism and plunger means housed therein. The compressible preload

mechanism may be adjusted from the exterior of the column end joint body

through a port.
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