Universal service tool

A latch mechanism and a self-supporting tool incorporating the latch mechanism are disclosed herein. The tool comprises a housing, a power transmission, a powered shaft and workpiece engaging means. The workpiece engaging means is secured to the housing and adapted to engage the workpiece in use such that the workpiece may be restrained against longitudinal and rotational movement with respect to the housing when worked by operation of the powered shaft. The latching system comprises a latch support on the housing which has a latching shoulder which projects laterally at one end thereof. A latch head is disposed outwardly from the shoulder and latching means is mounted on the head for movement between a retracted configuration in line with the head and an extended position projecting laterally from the head to overlie the shoulder and clamp a workpiece therebetween. The latch is activated by an actuator which is operable to effect movement of the latch between the extended and retracted positions in use.

This invention relates to a latch mechanism which is adapted to be 
releasably secured to a workpiece and a self-supporting tool which 
incorporates a latch mechanism for securing the tool with respect to a 
workpiece. 
In particular, this invention relates to a universal service tool suitable 
for use in module interchange systems, such as those required for 
servicing satellites in orbit. 
In the servicing of a satellite in orbit it is necessary to secure modular 
compartment to a servicing arm for the purpose of transporting them from 
one site to another. The tool required for this purpose must be capable of 
being releasably latched to the modules. Difficulty has been experienced 
in providing a simple and efficient latching mechanism in such a tool. 
PRIOR ART 
Difficulty have also been experienced in attempting to perform relatively 
simple operations in which a torque load is applied to an object because 
the object is not anchored in a manner which will resist the torque load. 
These difficulties have been overcome by the tool described hereinafter by 
providing a latching mechanism which interlocks the tool in the workpiece 
to prevent relative movement therebetween. 
In environments where it is difficult to service a tool, it is important to 
ensure that any electrically powered function may also be mechanically 
performed in the event of failure of the electrical system. This is 
achieved in the present tool by providing a manually operable mechanism 
which may be employed to move the latching mechanism between the latching 
and unlatching configurations and by providing a manually operable 
mechanism which may be used to drive the powered drive shaft. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide a tool which is adapted 
to be secured with respect to a workpiece in a manner to prevent relative 
movement between the tool and the workpiece. 
It is an object of the present invention to provide a tool which is adapted 
to be secured with respect to a workpiece in a manner to prevent relative 
movement between the tool and the workpiece during the application of a 
work load by a work shaft carried by the tool to a component carried by 
the workpiece. 
It is a further object of the present invention to provide a simple and 
efficient latching mechanism for securing a tool or the like to a 
workpiece or the like. 
According to one aspect of the present invention, a self-supporting tool 
comprises a housing, a power source mounted on said housing, a powered 
shaft supported by said housing to extend therefrom along the first axis, 
said shaft being operably connected to said power source to be driven by 
it in use, a workpiece engaging means mounted on said housing laterally 
outwardly from said shaft, said workpiece engaging means being secured to 
said housing to prevent rotation about said powered shaft and adapted to 
engage a workpiece in use such that the workpiece may be restrained 
against longitudinal and rotational movement with respect to said housing 
when worked by operation of the powered shaft. 
According to a further aspect of the present invention, a latch assembly 
comprises a latch support means, a latching shoulder projecting laterally 
at a first end of said support means, a latch actuator rod having a first 
end and a second end, said actuator rod being slidably mounted in said 
support means to reciprocate longitudinally between an extended position 
and a retracted position, said first end projecting outwardly from said 
shoulder, a latching head mounted at said first end of said actuator rod, 
a pair of latch arms each having an upper arm portion and a forearm 
portion, the proximal end of each upper arm portion being pivotally 
connected at the inner end of the head, one at each side thereof, the 
distal end of each upper arm portion being pivotally connected to the 
proximal end of the forearm portion and the distal end of each forearm 
being pivotally mounted on a retaining collar adapted to retain the distal 
ends of the forearm portion adjacent the latch actuator rod, said latch 
arms articulating in response to movement of said head such that when said 
head is in said extended position, the arms are extended and arranged in 
line with the head and when the head is in the retracted position, the 
arms are bent such that the forearm portions project laterally to overlie 
said shoulders to clamp a workpiece therebetween in use, latch drive means 
operable to drive said actuator rod relative to said support means between 
said extended position and said retracted position.

With reference to FIG. 1 of the drawings, reference numeral 10 refers 
generally to a shuttle craft in which a module 12 of a satellite 14 is 
being replaced by operation of a tool 16 mounted on the remote manipulator 
arm 18 of the shuttle craft. 
The structure of the tool 16 is more clearly illustrated with reference to 
FIG. 2 of the drawings in which the reference numeral 20 refers generally 
to a housing which supports a power source 22 and in which the power 
transmission mechanism 24 is mounted. A powered shaft assembly is 
generally identified by the reference numeral 26 and a pair of latch 
assemblies are each identified by the reference numeral 28. 
The housing 20 may be mounted as shown in FIG. 1 at an interface with the 
remote manipulator arms 16 or it may interface with a manually engageable 
unit 30 (FIG. 9). In either case, a pair of mounting screws and locking 
nuts generally identified by the reference numeral 32 may be used for 
securing the housing 20 to the remote manipulator arm 16 or the manually 
engageable unit 30. An electronics pack 34 is provided for use in 
connecting the controls to the various drive units whereby the drive units 
may be remotely controlled. 
The housing 20 comprises a base 36 and a shaft support 38. The main power 
source 22 comprises an electric motor and gear reduction assembly 40 which 
is secured to the base 36 of the housing with the inner end 42 of its 
drive shaft projecting into the housing and the outer end 44 of its drive 
shaft exposed at the other end of the motor. A bevelled gear 46 is mounted 
at the inner end of the drive shaft 42. The inner end 42 of the motor 
shaft forms the input drive shaft of the power transmission assembly 24. 
The powered transmission shaft 48 forms the power output shaft of the 
power transmission means and is mounted for rotation in the shaft support 
38 by means of a plurality of bearings 50. The output end 52 of the 
transmission shaft 48 is splined and projects through an opening 54 formed 
in the outer end of the shaft support 38 (FIG. 8). As shown in FIG. 8 of 
the drawings, recess 56 is formed in the outer end of the shaft support 38 
concentric with the output end 42 of the power transmission shaft. 
The powered shaft assembly 26 comprises a shaft 58, a sleeve 60 and socket 
63. The inner end of the shaft 60 is formed with a splined passage 64 
(FIG. 9) adapted to receive the output end 52 of the transmission shaft. 
The outer end of the shaft 58 is formed with splined portion 57 and an end 
portion 59 of reduced diameter. The inner end of the socket 63 is splined 
to slidably receive the splined portion 57 and the outer end of the socket 
63 is formed to provide a nut engaging socket portion 65. A collar 67 is 
formed within the socket 62 and the end portion 59 projects through the 
collar 67 and has a locking ring 69 mounted thereon. A compression spring 
71 extends between the collar 67 and the shoulder formed at the inner end 
of portion 57. The spring 71 normally urges the socket 63 to the extended 
position shown in FIG. 2. 
A bayonet-type connection is formed between the sleeve 60 and the shaft 
support 38. The bayonet connection includes a bayonet lock plate 66 and a 
bayonet retaining plate 68 which fits within the recess 56 and is retained 
by mounting screws 70. Bayonet lugs 72 project from the end of the collar 
80 and are adapted to pass into the passages formed in the bayonet lock 
plate and bayonet retaining plate and to be retained therein in use by 
rotation in a conventional bayonet-type mounting action. A slide 74 is 
mounted on the shaft support 38 so that its outer end is normally urged by 
a spring 76 to a position projecting forwardly from the support 38 to an 
extent sufficient to overlie any one of the flats 78 formed in the collar 
80 of the sleeve 60, thus, preventing the rotation of the sleeve 60 to 
permit release of the bayonet connection until the slide 74 is moved to a 
position withdrawing its outer end from the position overlying the flats 
78. 
As previously indicated, a pair of latch assemblies 28 are arranged one on 
either side of the powered shaft assembly 26. With reference to FIGS. 4 
and 5 it will be seen that the latch assemblies are supported at their 
front end by arms 82 which project laterally from the shaft support 38. 
The latch assemblies 28 extend rearwardly from the arms 82 to neck 
portions 84 which project from the base 36. A latch motor and gearhead 
assembly 86 is supported by the base 36 and has an output shaft 88. A 
threaded ball screw 90 is connected to the output shaft 88 of the assembly 
86 through a coupler 92 which is mounted for rotation in bearings 94, and 
is retained by a lock nut 93. A carriage assembly is mounted on the ball 
screw 90. The carriage assembly 96 comprises a ball nut 98 mounted in a 
retaining housing 100. The ball nut 98 is retained against rotation by a 
face plate 101 which is secured to the housing 100. The housing 100 has a 
recess 102 opening inwardly from one end thereof in which a pair of key 
slots 104 are formed. The slots 104 are adapted to engage ridges 85 formed 
on the neck portion 84 thus limiting the movement of the retaining housing 
100 to axial movement with respect to the ball screw 90. The carriage 
assembly 96 also includes a manual drive tube 106 which is threadably 
mounted on the retaining housing 100. The drive tube 106 is normally 
retained in a set position with respect to the housing 100 by means of 
locking ball 108 which is resiliently urged by means of a spring 113 into 
a recess 110 formed in the drive tube 106. The drive tube 106 can be 
manually rotated relative to the retaining housing 100 by initially 
applying sufficient force to depress the locking ball with the result that 
the drive tube 106 can be manually moved longitudinally with respect to 
the retaining housing 100. 
A mounting plate 112 is mounted on the arm 82 and has a neck 114 projecting 
forwarding therefrom and a shoulder 116 projecting laterally from the neck 
114. The neck 114 has side walls 113 projecting forwardly therefrom. A 
latch shaft 118 is slidably mounted in the mounting plate 112. The latch 
shaft 118 has a collar 120 projecting radially outwardly therefrom so as 
to bear against an inner face of mounting plate 112. A lock nut 122 is 
threadedly mounted at the inner end of the latch shaft 118 to retain a 
compression spring 124 in a position bearing against a washer 123 an inner 
face of the drive tube 106. A compression spring 126 bears against the 
shoulder 120 of the latch shaft 118 and a spring retaining collar 128 
located at the outer end of the drive tube 106. A further spring 130 
extends between the retainer 128 and an inner face of the mounting plate 
112. 
A latching head 132 is mounted at the outer end of the shaft 118 and is 
located between the side walls 113 of the neck 114. A pair of latching 
arms generally identified by the reference numeral 134 are located one at 
each side of the shaft 118. The latching arms 134 each include an upper 
arm portion 136 and a forearm portion 138. The proximal end of the upper 
arm portion 136 is pivotally mounted by means of a pivot pin 139 to the 
inner end of the head 132. The distal end of the upper arm portion 136 is 
pivotally connected by means of a pivot pin 140 to the proximal end of the 
forearm portion. The distal end of the forearm portion is pivotally 
mounted by means of a pivot pin 142 to the side walls 113. Springs 143 are 
mounted on the neck 114 by means of mounting screws 144. The springs 143 
normally urge the arms outwardly and prevent inward buckling when the head 
132 is retracted in use. 
In use, movement of the latch shaft 118 between the extended position shown 
in FIG. 6 of the drawings and the retracted position shown in FIG. 7 of 
the drawings results in movement of the head 132 relative to the mounting 
plate 112 and causes the link arms to articulate from the in line position 
shown in FIG. 6 to the clamping position shown in FIG. 7 in which the 
forearm portions 138 project laterally outwardly to overlie the shoulders 
116. When the forearms 138 are in the position shown in FIG. 7, they may 
be used to effectively clamp the latch assemblies to a mounting bracket 
162. 
Referring to FIG. 5 of the drawings, it will be seen that a limit switch 
assembly generally identified by the reference numeral 150 is supported by 
the housing 136 in a position to be operated by an actuator arm 148 which 
is mounted on the threaded nut assembly 96 for movement therewith. The 
limit switch assembly 150 includes a limit switch 152 which functions to 
indicate the limit of the extent of the retracting movement of the head 
132 and a limit switch 154 serves to indicate the limit of the extension 
of the head 132 in co-operation with the limit switch actuator 148. 
The workpiece in association with which the preferred embodiment of the 
tool described above is illustrated in FIGS. 3, 4 and 5 of the drawings. 
The workpiece is generally identified by the reference numeral 156. In 
this embodiment, the workpiece 156 is a module latch mounted on a module 
12. The latch includes a latch housing 158, a guide tube 160, mounting 
bracket 162 and threaded latch bolt 164. The latch housing 158 has a 
through passage 166 within which the head of the bolt 164 is seated with 
the threaded stem of the bolt 164 extending outwardly therefrom. The guide 
tube 160 has a through passage 168 aligned with the through passage 166. 
The mounting bracket 162 has a through passage 170 aligned with the 
through passage 168 of the guide tube 160. A pair of notches 172 extend 
laterally inwardly from the side edges of the mounting bracket 162 one on 
either side of the through passage 170. The notches 172 are proportioned 
and arranged to receive the latching heads 132 when the latching heads are 
in the extended position. 
In use, the required powered shaft assembly is selected and operably 
connected to the housing. With the latching head in the extended postion, 
the manipulator arm 18 is activated to position the tool 16 in relation to 
the workpiece 156 such that the powered shaft assembly 26 is aligned with 
the through passage 170 of the face plate 162 and the latch heads 132 are 
aligned with the notches 172 of the face plate. The manipulator arm 18 is 
then activated to cause the powered shaft assembly 26 to enter the passage 
170 and to pass through the guide tube 160 to an extent sufficient to 
position the socket 63 in driving engagement with the head of the latching 
screw 164. It will be noted that if the socket portion 65 is not aligned 
with the head of the latching screw 164 it will telescope on the splined 
portion 57 and compares the spring 71 with the result that when the shaft 
118 is subsequently driven the socket will eventually be aligned with the 
nut (when shaft 58 is rotated) and the spring 71 will drive the socket 
portion 65 onto the nut. In this position, the shoulder 116 of the latch 
assembly 28 bears against the front face of the face plate 162. The latch 
motor 86 is, then, activated to move the latch head to the retracted 
position causing the latch arms to assume the position shown in FIG. 7 of 
the drawings in which the face plate 162 is clamped between the forearm 
portions 138 and the shoulder 116, thereby, locking the tool to the face 
plate and, therefore, the workpiece, to prevent movement of the tool 
housing relative to the workpiece. The power source 22 may, then, be 
activated to rotatably drive the powered shaft 58 so that the socket will 
apply a torque to the head of the latching bolt 164 to cause it to rotate 
to engage or release a supporting structure. After the work has been 
completed, the tool 16 may be disconnected from the workpiece and the 
powered shaft assembly may be disconnected from the housing by reversing 
the procedures described above. 
The powered shaft assemblies 26 are normally stored in a storage rack, such 
as the rack illustrated in FIG. 9 and identified by the reference numeral 
180. 
FIG. 9 of the drawings illustrates a further embodiment of the present 
invention in which, the housing 20 is supported by a manually engageable 
unit 30 which has a grip handle 190 with various control buttons 192, 194 
being provided for controlling the operation of the powered drive shaft 
and latching mechanisms. In addition, in the embodiments illustrated in 
FIG. 9, the sleeve 60 of the powered shaft assembly 26 has a face plate 
196 mounted thereon which extends outwardly therefrom and in which latch 
passages 198 are formed. The latch arms 28 are arranged to extend through 
the passages 198. A handle 200 is connected to the face plate 196 to 
provide handleability during service. As shown in FIG. 9, a plurality of 
powered shaft assemblies 26a, 26b, 26c, 26d are provided each having a 
workhead of a different character for different applications. Some of the 
heads of the work tools may be in the form of grinding wheels, cutting 
wheels or the like. 
Various modifications of the apparatus of the present invention will be 
apparent to those skilled in the art. For example, the powered 
transmission system may be modified to impart a reciprocating or hammer 
load to the powered shaft. 
From the foregoing, it will be apparent that the tool of the present 
invention is readily adapted to be secured with respect to a workpiece in 
a manner so that loads can be applied by the tool to the workpiece while 
the workpiece is held rigidly with respect to the tool. 
The latching mechanism described herein provides a simple and reliable 
structure which permits the securing of two mechanism one to the other. It 
will be apparent that the latching assembly alone provides a mechanism 
which is well suited for use in transporting items from one location to 
another.