Strut dispenser for erecting truss structures in extraterrestrial space

An apparatus (10) for dispensing struts (11 and 12) for use by an astronaut in erecting a truss structure in extraterrestrial space comprises a frame to which a platform (16) is attached. The astronaut anchors himself to the platform (16) while erecting the truss structure. Pairs of retainer assemblies for securing opposite ends of struts of different lengths, i.e., the pair of retainer assemblies (22 and 23) for the struts (11), and the pair of retainer assemblies (22' and 23') for the struts (12), are also attached to the frame. One retainer assembly (22 or 22') from each pair is positioned within the astronaut's reach when he is anchored to the platform (16), and the other retainer assembly (23 or 23') from each pair is positioned remote from the astronaut's reach. Each of the remote retainer assemblies (23 and 23') comprises a plurality of spring-loaded receptacles (41) for receiving one end of the corresponding struts (11 or 12). Each of the retainer assemblies (22 and 22') within the astronaut's reach comprises a plate having recesses (51) for receiving the other end of the corresponding struts (11 or 12). Putting a strut (11 or 12) into, or removing a strut (11 and 12) from, the apparatus (10) is accomplished by pushing the strut (11 or 12) against the bias of the corresponding spring-loaded receptacle (41), so that the end of the strut (11 or 12) received by the corresponding recess (51) is able to clear the retainer assembly (22 or 22').

TECHNICAL FIELD 
This invention relates generally to the erection of truss structures, and 
more particularly to an apparatus for dispensing struts as needed in 
erecting a large-scale truss structure in extraterrestrial space. 
BACKGROUND OF THE INVENTION 
A technique for erecting a large-scale truss structure from a kit 
comprising a plurality of struts and nodal elements is described in U.S. 
Pat. No. 4,679,961 which is incorporated herein by reference. 
Quick-connecting coupling fixtures of the type disclosed in U.S. Pat. No. 
4,679,961 are of particular advantage to an astronaut in securing the ends 
of struts to the mating ends of lugs projecting from nodal elements, when 
erecting a large-scale truss structure in the weightless environment of 
extraterrestrial space. However, the speed with which an astronaut can 
erect a truss structure using such quick-connecting coupling fixtures to 
couple the struts and nodal elements together depends to a large extent 
upon the time required to maneuver each strut into suitable position with 
respect to each corresponding lug so that the quick-connecting coupling 
fixture for securing the strut to the lug can be activated. 
The time and effort required to erect a truss structure in extraterrestrial 
space from struts and nodal elements as described in U.S. Pat. No. 
4,679,961 could be minimized by using a dispenser from which the astronaut 
can obtain the struts and nodal elements in proper sequence as needed to 
erect the truss structure according to a predetermined construction plan. 
SUMMARY OF THE INVENTION 
The present invention provides an apparatus for storing and dispensing 
struts of the type disclosed in U.S. Pat. No. 4,679,961, particularly for 
application in erecting truss structures in extraterrestrial space. 
A strut dispenser according to the present invention comprises a frame to 
which are attached: (1) a platform upon which an astronaut can anchor his 
feet while erecting the truss structure, and (2) a pair of strut-retainer 
assemblies adapted for retaining opposite ends of each one of a plurality 
of struts to which quick-connecting coupling fixtures of a type also 
disclosed in U.S. Pat. No. 4,679,961 are attached. A first one of the 
strut-retainer assemblies is attached to the frame at a location that is 
within easy reach of a work station at which the astronaut, while standing 
on the platform, can remove the struts in proper sequence and connect them 
to nodal elements in order to erect the truss structure. A second one of 
the strut-retainer assemblies is attached to the frame at a location 
remote from the astronaut's work station. 
The strut-retainer assembly within reach of the astronaut's work station 
comprises a plate having a plurality of recesses on one surface thereof. 
Each recess in the strut-retainer plate is configured to receive a 
hemicylindrical distal end of the cylindrical member of a coupling fixture 
of the type disclosed in U.S. Pat. No. 4,679,961. The strut-retainer 
assembly remote from the astronaut's work station comprises an apertured 
plate that supports a plurality of spring-loaded receptacles. Each 
receptacle is likewise configured to receive a hemicylindrical distal end 
of the cylindrical member of a coupling fixture of the same type. Such 
coupling fixtures are attached, one at each end, to each one of the struts 
stored in the dispenser. 
To remove a selected one of the struts from the dispenser, the astronaut 
uses one hand to grasp the coupling fixture that is attached to one end of 
the selected strut (i.e., the end of the selected strut within reach of 
his work station). With the one-hand grip on the coupling fixture, the 
astronaut then moves the selected strut longitudinally toward the 
strut-retainer assembly remote from his work station against a restoring 
force exerted by the spring-loaded receptacle holding the distal end of 
the cylindrical member of the coupling fixture attached to the opposite 
end of the strut. 
While the distal end of the cylindrical member of the coupling fixture at 
the opposite end of the strut remains in the spring-loaded receptacle at 
the remote strut-retainer assembly, the astronaut lifts the distal end of 
the cylindrical member of the coupling fixture in his grasp out of the 
recess in the plate of the strut-retainer assembly within reach of his 
work station. The astronaut then pivots the strut about the spring-loaded 
receptacle so that the end of the strut that is attached to the coupling 
fixture in his grasp is thereby moved away from the dispenser. When the 
coupling fixture in his grasp is clear of the retainer assembly, the 
astronaut then pulls the strut so that the coupling fixture at the 
opposite end of the strut is withdrawn from the spring-loaded receptacle. 
The strut is thereby removed from the dispenser, and can be maneuvered 
with the same one-hand grip in the weightlessness of extraterrestrial 
space into position for connection to the corresponding lug projecting 
from the appropriate nodal element.

BEST MODE OF CARRYING OUT THE INVENTION 
A prototype of a strut dispenser 10 according to the present invention is 
illustrated in FIG. 1. This prototype, substantially as shown in the 
drawing, was favorably evaluated by Lockheed Missiles & Space Company, 
Inc. in a test procedure that was conducted in a terrestrial environment 
in which the weightlessness of extraterrestrial space was simulated to 
some extent, i.e., the underwater environment of a swimming pool. However, 
the overall configuration of a strut dispenser that might be designed for 
use in erecting a particular kind of truss structure in extraterrestrial 
space could be quite different in certain respects from the configuration 
of the prototype illustrated in FIG. 1 without departing from the essence 
of the present invention. 
The strut dispenser 10 shown in FIG. 1 is designed to store and dispense 
strut assemblies and node assemblies generally of the kind disclosed in 
U.S. Pat. No. 4,679,961. In the particular embodiment illustrated in FIG. 
1, the strut dispenser 10 stores five struts 11 of a shorter length, and 
five struts 12 of a longer length. In principle, however, the strut 
dispenser 10 could be configured to store struts of any number of 
different lengths, and to store any number of struts of any particular 
length. The strut dispenser 10 shown in FIG. 1 also stores a plurality of 
node assemblies 13 (of which only one can be seen in the perspective of 
FIG. 1), where each node assembly 13 comprises a multifaceted nodal 
element 14 with a plurality of elongate lugs 15 projecting therefrom. In 
principle, however, the strut dispenser 10 could be configured to store 
any number of node assemblies 13. 
The strut dispenser 10 can be secured in a conventional manner to a support 
mechanism (not shown in FIG. 1), which can be extended or deployed from a 
vehicle such as a NASA space shuttle in the vicinity of a "building site" 
in extraterrestrial space where the struts 11 and 12 and the node 
assemblies 13 are to be connected together according to a predetermined 
plan in order to erect a truss structure. Connection of the struts 11 and 
12 to the node assemblies 13 is accomplished using quick-connecting 
coupling fixtures of the type disclosed in U.S. Pat. No. 4,679,961 which 
are attached to the ends of the struts 11 and 12. It is contemplated that 
the support mechanism for the strut dispenser 10 could comprise a rail or 
track along which the strut dispenser 10 would be moved to various 
positions as required by an astronaut to facilitate his task of erecting 
the truss structure. 
As shown in FIG. 1, the strut dispenser 10 comprises a frame to which a 
platform 16 is secured to provide a place for the astronaut to stand while 
removing the struts 11 and 12 and the node assemblies 13 from the strut 
dispenser 10, and while connecting them to form the truss structure. A 
pair of rigid straps 17 is secured to the platform 16 to receive the 
astronaut's feet, thereby anchoring him to the strut dispenser 10 while he 
is working to assemble the struts 11 and 12 and the node assemblies 13. 
Also, a brace 18 comprising a support member 19 and a handlebar 20 is 
secured to the frame of the strut dispenser 10 to enable the astronaut to 
control his own twisting motions while removing the struts 11 and 12 and 
the node assemblies 13 from the strut dispenser 10. 
To accommodate the different lengths of the struts 11 and 12, different 
pairs of strut-retainer assemblies are secured to the frame of the strut 
dispenser 10. The two members of each particular strut-retainer assembly 
pair are positioned with respect to each other to enable struts of a 
particular length to be stored. Thus, as illustrated in FIG. 1, the 
members of the pair comprising the strut-retainer assemblies 22 and 23 are 
positioned with respect to each other to store the shorter-length struts 
11, and the members of the pair comprising the strut-retainer assemblies 
22' and 23' are positioned with respect to each other to store the 
longer-length struts 12. (Most of the strut-retainer assembly 22' is 
blocked from view by the astronaut's body in the perspective of FIG. 1.) 
The strut-retainer assemblies 22 and 22' are secured to the frame of the 
strut dispenser 10 within easy reach of the astronaut when he is standing 
on the platform 16. The strut-retainer assemblies 23 and 23' are secured 
to the frame of the strut dispenser 10 at different locations 
corresponding to the different lengths of the struts 11 and 12, 
respectively, and (depending upon the lengths of the struts 11 and 12) are 
generally out of reach of the astronaut standing on the platform 16. In 
substantial particulars with respect to the concept of the present 
invention, the strut-retainer assembly 22' W can be identical to the 
strut-retainer assembly 22, and the strut-retainer assembly 23' can be 
identical to the strut-retainer assembly 23. 
The node assemblies 13 are secured to the strut-retainer assemblies 22 and 
22' within reach of the astronaut standing on the platform 16. In the 
prototype embodiment of the invention, spring clamps of conventional 
design (not visible in the perspective of FIG. 1) were attached to each of 
the strut-retainer assemblies 22 and 22' to grip one of the lugs 15 
projecting from the nodal element 14 of a corresponding one of the node 
assemblies 13. 
Referring to FIG. 2, coupling fixtures 31 generally of the type disclosed 
in U.S. Pat. No. 4,679,961 are shown attached to opposite ends of each 
strut 11. Each coupling fixture 31 comprises a solid circularly 
cylindrical member 35 surrounded by a hollow circularly cylindrical sleeve 
36. A proximal end of the cylindrical member 35 is secured to one end of 
the strut 11 (in a manner that may be conventional) so that the 
cylindrical member 35 extends coaxially with respect to the strut 11. A 
distal end of the cylindrical member 35 is hemicylindrically configured 
with an inner surface that is contoured to receive a correspondingly 
configured disc-like knob 150 at the distal end of one of the lugs 15. 
The disc-like knob 150 at the distal end of each elongate lug 15 is 
symmetric about the longitudinal axis of the lug 15, as described in U.S. 
Pat. No. 4,679,961. Thus, the distal end of the cylindrical member 35 
secured to one end of the strut 11 can be maneuvered by the astronaut so 
as to approach the distal end of the corresponding lug 15 of the 
appropriate node assembly 13 from any convenient angle in order to make 
overlapping side contact therewith. The knob 150 at the distal end of the 
lug 15 is received in mating engagement by the correspondingly configured 
inner surface of the distal end of the cylindrical member 35, whereupon 
the sleeve 36 is slid by the astronaut longitudinally over the distal ends 
of both the cylindrical member 35 and the lug 15 to achieve a secure 
coupling therebetween. 
In practicing the present invention in extraterrestrial space, the 
astronaut, while standing on the platform 16 with his feet anchored 
thereto by the straps 17, commences erection of the truss structure by 
removing a selected one of the node assemblies 13 and a selected one of 
the struts 11 from the dispenser 10. The technique whereby the selected 
strut 11 is removed from the dispenser 10 requires the use of only one 
hand. Thus, to remove the strut 11 from the dispenser 10, the astronaut 
grasps the coupling fixture 31 attached to the end of the strut 11 within 
reach of his work station (i.e., adjacent the strut-retainer assembly 22) 
with one hand. Then, with this one-hand grip, the astronaut moves the 
strut 11 longitudinally in the direction of the remote strut-retainer 
assembly 23. A spring-loaded receptacle (described hereinafter), which 
holds the distal end of the cylindrical member 35 of the coupling fixture 
31 attached to the opposite end of the strut 11, exerts a restoring force 
that must be overcome by the astronaut when moving the strut 11 toward the 
remote strut-retainer assembly 23. The coupling fixture 31 attached to the 
end of the strut 11 within reach of the astronaut's work station (i.e., 
the coupling fixture 31 in the astronaut's grip) is thereby lifted out of 
the strut-retainer assembly 22. After the coupling fixture 31 in the 
astronaut's grip has been lifted clear of the strut-retainer assembly 22, 
the astronaut pivots the strut 11 about the spring-loaded receptacle away 
from the dispenser 10 and then, with the same one-hand grip, pulls the 
strut 11 so that the coupling fixture 31 attached to the opposite end of 
the strut 11 is removed from the spring-loaded receptacle. 
After the ends of the strut 11 have been removed from the strut-retainer 
assemblies 22 and 23, respectively, the astronaut then maneuvers the strut 
11 with the same one-hand grip so that the hemicylindrical distal end of 
the cylindrical member 35 of the coupling fixture 31 in his grip is 
brought into overlapping side contact with the distal end of the 
corresponding lug 15 of the appropriate node assembly 13. After 
overlapping side contact has been made between the distal ends of the 
cylindrical member 35 and the lug 15, the astronaut then slides the 
cylindrical sleeve 36 longitudinally over the cylindrical member 35 from 
an OPEN position (as shown in FIG. 2) to a LOCKED position (not shown). In 
the LOCKED position, the cylindrical sleeve 36 surrounds the overlapping 
distal ends of the cylindrical member 35 and the lug 15, and thereby 
provides the secure coupling as described in detail in U.S. Pat. No. 
4,679,961. 
The remote strut-retainer assembly 23 comprises a plate 40, which supports 
a plurality of spring-loaded receptacles 41. Each receptacle 41 is 
configured to receive the distal end of the cylindrical member 35 of a 
corresponding one of the coupling fixtures 31 attached to one end of one 
of the struts 11. As illustrated in FIG. 3, each receptacle 41 has a cup 
portion 42 and a stem portion 43. The cup portion 42 of each receptacle 41 
has a circularly cylindrical side wall and a closed end wall, which define 
a volume in which the distal end of the cylindrical member 35 is received. 
The stem portion 43 of each receptacle 41 is circularly cylindrical, and 
extends outwardly from the closed end wall thereof. The stem portion 43 is 
coaxial with respect to the cylindrical side wall of the cup portion 42, 
and has an outside diameter that is smaller than the outside diameter of 
the cylindrical side wall of the cup portion 42. In the prototype 
embodiment, the stem portion 43 of the receptacle 41 forms an integral 
structure with the cup portion 42. However, in principle the stem portion 
43 and the cup portion 42 could be separate members joined together to 
form the receptacle 41. A truncated conical boss 44 extends axially from 
the closed end wall of the cup portion 42 into the volume provided by the 
receptacle 41 to receive the distal end of the cylindrical member 35. 
Circularly cylindrical bores extend perpendicularly through the plate 40 to 
receive the stem portions 43 of corresponding spring-loaded receptacles 
41. The bores are dimensioned so that the stem portion 43 of each 
receptacle 41 makes sliding frictional contact with the cylindrical wall 
of the bore in which it is received. The plate 40 is oriented by the 
strut-retainer assembly 23 so as to be perpendicular to the struts 11 
stored in the dispenser 10. 
In the prototype embodiment shown in FIG. 3, spring-loading of each 
receptacle 41 is accomplished by attaching one end of each member of a 
pair of helical springs 45 to the stem portion 43 of the receptacle 41, 
and by attaching the other end of each member of the pair of springs 45 to 
the plate 40. When the struts 11 are not present in the dispenser 10, each 
of the receptacles 41 is caused by the springs 45 attached thereto to 
assume a predetermined neutral position (i.e., a position of minimum 
potential energy), which is substantially the same with respect to the 
plate 40 for all of the receptacles 41. The springs 45 attached to the 
stem portion 43 of the receptacle 41 are stretched when the receptacle 41 
is pushed away from its neutral position, which occurs when the stem 
portion 43 slides within the corresponding bore through the plate 40. 
Stretching of the springs 45 results when the astronaut moves the strut 11 
by lifting the distal end of the cylindrical member 35 of the coupling 
fixture 31 attached to the end of the strut 11 within reach of his work 
station away from the strut-retainer assembly 22. 
The strut-retainer assembly 22 within reach of the astronaut's work station 
comprises a plate 50, which likewise has an orientation perpendicular to 
the struts 11 stored in the dispenser 10. As shown in FIG. 4, cylindrical 
recesses 51 are formed on a surface of the plate 50 facing toward the 
plate 40. The recesses 51, like the cup portions 42 of the receptacles 41, 
are configured to receive the distal ends of the cylindrical members 35 of 
the coupling fixtures 31 attached to the ends of the struts 11. Each 
recess 51 has a circularly cylindrical side wall and a bottom wall, which 
define a volume in which the distal end of the cylindrical member 35 is 
received. A truncated conical boss 52 extends axially from the bottom wall 
of the recess 51 into the volume provided to receive the distal end of the 
cylindrical member 35. 
To place one of the struts 11 into the dispenser 10 for storage, the distal 
end of the cylindrical member 35 of the coupling fixture 31 attached to 
one end of the strut 11 is inserted into the cup portion 42 of one of the 
receptacles 41 of the strut-retainer assembly 23 remote from the 
astronaut's work station. The boss 44 within the receptacle 41 makes 
contact with the inner surface of the hemicylindrically configured distal 
end of the cylindrical member 35, thereby guiding the strut 11 into almost 
perpendicular orientation with respect to the plate 40. The strut 11 is 
then moved longitudinally toward the strut-retainer assembly 23 against 
the restoring force of the springs 45 connecting the stem portion 43 of 
the receptacle 41 to the plate 40. The direction in which the strut 11 is 
moved deviates by only a small angle from perpendicularity with respect to 
the plate 40, whereby the stem portion 43 of the receptacle 41 is caused 
to slide within the corresponding bore in the plate 40 so that the strut 
11 can be pivoted about the boss 44 in the receptacle 41. The strut 11 is 
then pivoted about the boss 44 to bring the distal end of the cylindrical 
member 35 of the coupling fixture 31 attached to the other end of the 
strut 11 near the astronaut's work station into alignment with a proper 
one of the recesses 51 in the plate 50 at which the strut 11 is 
perpendicular with respect to both the plate 40 and the plate 50. 
When the strut 11 has been aligned with the proper recess 51 in the plate 
50, the force applied by the astronaut to move the strut 11 toward the 
remote strut-retainer assembly 23 against the bias of the springs 45 is 
then released. The springs 45 then urge the receptacle 41 to return to its 
neutral position, and thereby drive the distal end of the cylindrical 
member 35 of the coupling fixture 31 attached to the end of the strut 11 
near the astronaut's work station into the proper recess 51 in the plate 
50. The boss 52 within the recess 51 makes contact with the inner surface 
of the hemicylindrically configured distal end of the cylindrical member 
35, thereby guiding the strut 11 into perpendicular orientation with 
respect to the plate 50. A view of the strut 11 thereby secured in the 
dispenser 10 is shown in FIG. 5. 
A perspective view of the strut-retainer assembly 23 that is remote from 
the astronaut's work station is shown in FIG. 6 in which the internal 
configuration of the cup portions 42 of the receptacles 41 is seen. A view 
of the boss 44 in each receptacle 41 is also seen in FIG. 6. A perspective 
view of the strut-retainer assembly 22 that is adjacent the astronaut's 
work station is shown in FIG. 7 in which the internal configuration of the 
recesses 51 in the plate 50 is seen. A view of the boss 52 in each recess 
51 is also seen in FIG. 7. 
In erecting a truss structure in extraterrestrial space, the sequence in 
which the individual struts 11 are to be removed from the dispenser 10 
would be specified according to a predetermined construction plan. In 
order to minimize fatigue suffered by the astronaut in erecting the truss 
structure, it would be desirable for the astronaut to be able to complete 
the erection as quickly as possible. Therefore, the individual struts 11 
should be stored in the dispenser 10 in such a way that their attached 
coupling fixtures 31 are oriented so that the astronaut can, with one 
hand, remove a selected strut 11 and maneuver it to where the 
hemicylindrical distal end of the cylindrical member 35 of the coupling 
fixture 31 at one end of the strut 11 is in proper position to make 
overlapping side contact with the distal end of the corresponding lug 15 
on the appropriate node assembly 13. 
In accordance with the present invention, each strut 11 is stored in the 
dispenser 10 with a predetermined rotational orientation, so that there 
will be no need for the astronaut to rotate the strut 11 about its 
longitudinal axis in order for the coupling fixture 31 to have the proper 
orientation for mating with the lug 15. In order to store the individual 
struts 11 with predetermined rotational orientations in the dispenser 10, 
semicircular covers 53 are provided over the recesses 51 in the plate 50. 
Each semicircular cover 53 is supported on the boss 52 extending axially 
within the corresponding recess 51, and is secured to the boss 52 by a 
screw 54 that extends along the cylindrical axis of the recess 51. As 
shown in FIG. 7, each semicircular cover 53 over each corresponding recess 
51 has a predetermined rotational orientation, which defines the 
rotational orientation of the hemicylindrical distal end of the 
cylindrical member 35 of the coupling fixture 31 attached to the end of 
the strut 11 within reach of the astronaut's work station. 
In an operational version of the strut dispenser 10 according to the 
present invention, spring-loading of each receptacle 41 could be 
accomplished in a manner different from that shown in FIG. 3 for the 
prototype. An alternative type of spring-loaded receptacle 41' that is 
contemplated for use in place of the above-described receptacle 41 is 
illustrated in perspective view in FIG. 8 and in cross-sectional view in 
FIG. 9. 
As seen in FIG. 9, a cylindrical liner 60 is fitted in each bore through 
the plate 40 so that a circumferentially flanged end portion 61 of the 
liner 60 overlaps the side of the plate 40 facing toward the plate 50. The 
liner 60 is secured to the plate 40 by machine screws 62, which pass 
through holes in the flanged portion 61 and enter correspondingly aligned 
screw-threaded holes in the surface portion of the plate 40 around the 
bore. The other end of the liner 60 extends through the bore beyond the 
opposite surface of the plate 40 facing away from the plate 50. The 
portion of the liner 60 within the bore between opposite surfaces of the 
plate 40 has a smaller internal diameter, and the remaining portion of the 
liner 60 extending outside the bore beyond the surface of the plate 40 
facing away from the plate 50 has a larger internal diameter. There is a 
sharp transition from the smaller internal diameter to the larger internal 
diameter of the liner 60 at the plane of the surface of the plate 40. This 
transition from the smaller internal diameter to the larger internal 
diameter forms an annular step 63 within the liner 60. 
The receptacle 41' comprises a cup member 42' and a stem member 43'. The 
cup member 42' has substantially the same internal configuration as the 
cup portion 42 of the receptacle 41 shown in FIG. 3 for the prototype. The 
stem member 43' is a functional analog of the stem portion 43 of the 
receptacle 41 of the prototype, but is hollow and internally contains a 
spring (described hereinafter) instead of being externally connected to 
the plate 40 by means of springs as was the stem portion 43 of the 
receptacle 41. 
The stem member 43' is of circular cylindrical configuration, and the cup 
member 42' is secured to one end thereof (i.e., a proximal end extending 
through the corresponding bore in the plate 40 toward the plate 50). As 
shown in FIG. 9, the cup member 42' is secured to the proximal end of the 
stem member 43' by machine screws 64, which pass through holes in the 
closed end of the cup member 42' and enter correspondingly aligned 
longitudinally extending screw-threaded holes positioned on the proximal 
end of the stem member 43'. The other end of the stem member 43' (i.e., a 
distal end) has a flanged portion 65, which overlaps the annular step 63 
within the liner 60. 
The stem member 43' has an external diameter dimensioned so that sliding 
frictional contact is made between the stem member 43' and the interior 
cylindrical wall of the portion of the liner 60 within the bore between 
the opposite surfaces of the plate 40. The flanged portion 65 of the stem 
member 43' extends laterally outward to make sliding frictional contact 
with the interior cylindrical wall of the remaining portion of the liner 
60 extending outside the bore beyond the surface of the plate 40 facing 
away from the plate 50. Contact of the flanged portion 65 of the stem 
member 43' with the annular step 63 inside the liner 60 limits the travel 
of the stem member 43', and thereby prevents the receptacle 41' from 
leaving the liner 60. 
A helical spring 66 is disposed coaxially within the hollow stem member 
43'. One end of the spring 66 abuts the outside surface of the closed end 
wall of the cup member 42', and the other end of the spring 66 extends 
toward the flanged end of the stem member 43' to a position that is 
approximately co-planar with the annular step 63. The end of the liner 60 
projecting outside the bore through the plate 40 in a direction away from 
the plate 50 is screw-threaded, and a correspondingly screw-threaded bolt 
67 is received therein. The bolt 67 has a head portion 68, and four 
successive circularly cylindrical shank portions of progressively smaller 
diameter extending from the head portion 68. The head portion 68 is 
hexagonally cylindrical in the preferred embodiment to facilitate 
engagement thereof by a conventional wrench. A first shank portion 69 of 
the bolt 67 is screw-thread, and has a diameter dimensioned to engage the 
screw-threaded end of the liner 60. A second shank portion 70 of the bolt 
67 has a smaller diameter, which is dimensioned to fit with frictional 
contact within the portion of the liner 60 extending outside the bore of 
the plate 40. A third shank portion 71 of the bolt 67 has an even smaller 
diameter, which is dimensioned to fit with frictional contact within the 
hollow stem member 43'. A fourth shank portion 72 of the bolt 67 has the 
smallest diameter, which is dimensioned to fit longitudinally within the 
helical spring 66. A step-like transition between the third shank portion 
71 and the fourth shank portion 72 provides an annular step 73 against 
which the end of the spring 66 that is co-planar with the step 63 abuts. 
The bolt 67, and in particular the annular step 73 on the bolt 67, 
functions as a stopper to prevent motion of the spring 66 outside the 
liner 60. When a force applied by the astronaut to the strut 11 causes the 
stem portion 43' of the receptacle 41' to slide longitudinally within the 
liner 60, the spring 66 becomes compressed. Compression of the spring 66 
produces a restoring force, which urges the receptacle 41' to return to an 
extended (or "neutral"0 ) position as shown in FIG. 9. When the force 
applied by the astronaut is removed, the restoring force of the spring 66 
drives the receptacle 41' back to the extended position shown in FIG. 9. 
In the prototype embodiment, the plate 50 of the strut-retainer assembly 22 
located within reach of the astronaut's work station was mounted upon a 
support plate 80 (not visible in the perspective of FIG. 1). As shown in 
FIG. 10, a conventional spring clamp 81 was attached by machine screws 82 
to a soffit surface of the plate 80 (i.e., to an undersurface thereof 
facing away from the plate 50) in order to grip the a neck portion of one 
of the lugs 15 of one of the node assemblies 13. An alternative type of 
clamp 81', which is contemplated for use in place of the conventional 
spring clamp 80 in an operational version of the strut dispenser 10, is 
illustrated in side view in FIG. 11 and in cross-sectional view in FIG. 
12. 
The clamp 81' comprises a sleeve 83 having a circularly cylindrical 
interior wall, which defines a volume dimensioned to receive the lug 15 of 
the node assembly 13. One end of the sleeve 83 has an outwardly flanged 
portion 84 through which holes are drilled at substantially equiangular 
intervals. Correspondingly positioned holes are drilled through the 
support plate 80 in alignment with the holes through the flanged portion 
84, and bolts 85 pass through the holes so aligned. Nuts 86 are tightened 
on the ends of the bolts 85 to secure the sleeve 83 to the support plate 
80. Two circularly cylindrical housings 90 are formed integrally with the 
sleeve 83, and extend in opposite directions from each other along a 
common axis substantially perpendicular to the cylindrical axis of the 
sleeve 83. Each housing 90 has a circularly cylindrical interior wall, 
which defines an interior volume that is in communication with the volume 
defined by the sleeve 83 for receiving the lug 15. 
Fitted into each housing 90 is a circularly cylindrical plug 91, which is 
dimensioned to make sliding frictional contact with the cylindrical 
interior wall of the housing 90. A detent member 92 is secured to one end 
of the other 91 (as by screw-threaded engagement in a bore formed therein) 
so as to project out of the interior volume of the housing 90 into the 
volume defined by the sleeve 83. A helical spring 93 is fitted into the 
housing 90 between the other end of the plug 91 and a flat-ended bolt 94 
that is screw-threaded into the distal end of the housing 90. One end of 
the spring 93 abuts the plug 91, and the other end of the spring 93 abuts 
the bolt 94. A pair of projecting members 95 extend longitudinally from 
the detent member 92 into the volume defined by the sleeve 83. The 
projecting members 95 are parallel to each other, and serve as mountings 
for opposite ends of an axel 96. A roller wheel 97 is mounted on the axel 
96 for rotation in a plane parallel to the projecting members 95. 
Each housing 90 is constricted at its proximal end (i.e., the end 
communicating with the volume defined by the sleeve 83) in order to 
prevent the cylindrical plug 91 from leaving the housing 90. As shown in 
FIG. 12, an annular ridge extends inwardly from the cylindrical wall 
adjacent the proximal end of the housing 90, and a peripheral annular 
portion of the end of the plug 91 to which the detent member 92 is 
attached abuts the annular ridge. The roller wheel 97 supported by the 
projecting members 95 extends into the volume defined by the sleeve 83 so 
as to make contact with the disc-like knob 150 at the distal end of the 
lug 15, when the lug 15 is being inserted into the sleeve 83. 
When the disc-like knob 150 at the distal end of the lug 15 reaches the 
roller wheels 97 as the lug 15 is being inserted into the sleeve 83, the 
knob 150 thereby pushes the roller wheels 97 (and hence also the 
cylindrical plugs 91) into their respective housings 90 against the biases 
of the springs 93. In this way, the knob 150 is forced past an obstruction 
in the sleeve 83 caused by the roller wheels 97. However, after the knob 
150 has passed the position of the roller wheels 97, the restoring forces 
exerted by the springs 93 drive the plugs 91 back to their respective 
positions at which the detent members 92 (and the projecting members 95 
extending therefrom) cause the roller wheels 97 to form the obstruction in 
the sleeve 83. 
When the roller wheels 97 are fully returned to their positions of 
obstruction in the sleeve 83 after the knob 150 on the distal end of the 
lug 15 has been forced past the roller wheels 97, the roller wheels 97 
then occupy a region adjacent the neck portion of the lug 15 between the 
knob 150 and an intermediate portion of the lug 15, and thereby obstruct 
passage of the knob 150 out of the sleeve 83. In this way, the node 
assembly 13 to which the lug 15 is attached is retained by the sleeve 83. 
To remove the node assembly 13 from the dispenser 10, the astronaut pulls 
the node assembly 13 with a sufficient force so that the disc-like knob 
150 at the distal end of the lug 15 pushes against the roller wheels 97 so 
as to cause the plugs 91 to move into their respective housings 90 against 
the bias of the springs 93 until the roller wheels 97 no longer obstruct 
passage of the knob 150 out of the sleeve 83. 
The present invention has been described above in terms of a prototype and 
certain alternative embodiments, which were designed for a particular 
application. However, other embodiments and applications would be apparent 
to practitioners skilled in the art upon perusal of the foregoing 
description and the accompanying drawing. Therefore, the description and 
drawing presented above are to be deemed as illustrative of the invention, 
which is defined by the following claims and their equivalents.