Containment assembly for spin table

A system for releasably restraining a first element and a second element is disclosed. The containment system uses a tensioner to urge a clamp into contact with the first element and with the second element, and a release selectively operates the tensioner to remove the clamp from contact with the first and second elements to permit relative movement therebetween. The clamp is particularly useful in maintaining a gap between the first and second elements which permits relative movement between the first and second elements after the clamp is removed.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a system which restrains components to 
prevent relative movement, and then releases to permit movement of the 
components. More particularly, the present invention relates to a 
containment system which restrains movable components during travel, such 
as in the launch of a satellite, and then releases the components to 
permit movement. 
2. The Prior Art 
The deployment of a satellite in space is typically performed after the 
satellite has been carried to a zero gravity orbit by a rocket booster or 
other vehicle. The satellite is lifted by the launch vehicle and is 
deployed into a higher stable orbit by imparting a rotational movement to 
the satellite as the satellite is released. This rotational movement is 
typically caused by a spin table connected to the launch vehicle which 
mechanically rotates and releases the satellite. The satellite or other 
payload can vary in size and weight. 
The successful deployment of payloads such as satellites presents an 
engineering challenge caused by numerous variables. For example, the 
system for retaining the payload must survive launch forces which may 
exceed the force of gravity by a multiple of ten. The temperatures 
affecting the system range from the ambient temperatures of the launch 
environment to the subzero temperatures in orbit. In addition, the 
deployment system must be sufficiently strong to handle these variables 
and the sheer mass of the payload in the most weight efficient manner, as 
the weight of the deployment system must be lifted by the launch vehicle. 
Existing spin tables have been developed to carry a satellite to the 
deployment elevation and to release the satellite. A spin table generally 
comprises a large ring gear rotated by pinion gears connected to two drive 
motors. The ring gear is connected by a rotating structure to the 
satellite, and this rotating structure rotates on a bearing engaged with 
the base structure of the system. Initially, the rotating structure 
contacts the base structure to prevent relative movement during launch. 
After the satellite has been raised to the deployment elevation, the 
rotating structure is displaced from contact with the base structure so 
that the ring gear and rotating structure can spin the satellite relative 
to the base structure. This displacement of the rotating structure can be 
accomplished by an off-load spring, shaped as a large Belleville spring, 
connected between the ring gear and the rotating structure. When the 
preloaded tension on the off-load spring is released, this spring 
displaces the rotating structure from contact with the base structure so 
that the drive motors can spin the ring gear and attached rotating 
structure and satellite. After the satellite reaches a selected angular 
speed, the satellite is release from the rotating structure. 
There are several disadvantages to using an off-load spring to separate the 
rotating structure from the base structure. For example, the manufacturing 
tolerances and specifications of the large off-load spring are precise, 
and slight variations from such tolerances can result in failure of the 
entire system. In addition, the off-load spring is subjected to large 
temperature variations, and these variations can adversely affect the 
operation of the system. Although the spin table operates in a zero 
gravity environment, the spin table is typically tested under gravity. In 
a test of a payload having a weight of six tons, tremendous forces act 
against the off-load spring, and these forces complicate testing 
procedures. 
For these reasons, a need exists for an improved system for releasable 
restraining components. The system should be capable of handling large 
forces without movement, and should be easily removed for deployment of 
the components. 
SUMMARY OF THE INVENTION 
The present invention discloses an improved system for restraining 
components to prevent relative movement between the components. The system 
releasably restrains a first element and a second element which are 
separated by a gap. A clamp is adapted for contact with the first element 
and the second element, and a tensioner is capable of urging the clamp 
into contact with the first element to prevent relative movement between 
the first and second elements. A release operates the tensioner to remove 
the clamp from contact with the first and second elements. 
In another aspect of the invention, the system is adapted to a first 
element which is rotatable about the second element, and the clamp 
includes two ends which can be pulled together to urge the clamp into 
contact with the first and second elements. 
In another aspect of the invention, the clamp is insertable into the gap 
between the first and second elements to contact and to prevent relative 
movement between the first and second elements. This aspect of the 
invention prevents the first element from initially moving relative to the 
second element, and further maintains the gap between the first and second 
element to permit relative movement therebetween after the release 
operates the tensioner to remove the clamp from contact with the first and 
second elements. 
In another aspect of the invention, the system further comprises an 
improved bearing anchored to the first element and to the second element 
to permit relative movement therebetween after the release operates the 
tensioner to remove the clamp from contact with the first and second 
elements.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The present invention is particularly suitable in a spin table for 
imparting rotational motion to an object such as a satellite. Referring to 
FIG. 1, spin table 10 generally comprises circular rotating structure 12 
attached to ring gear 14, and pinion gears 16 attached to a two part 
stationary base 18. Pinion gears 16 are driven by motors 20 which are 
activated to engage ring gear 14 and to operate rotating structure 12. 
Rotating structure is connected to a satellite (not shown) or other 
payload which is releasably fastened to rotating structure 12 with 
pyrotechnic bolts or similar release mechanism (not shown). After the 
satellite has been lifted by a booster rocket or similar vehicle (not 
shown) to a selected elevation, rotating structure 12 is released from 
stationary base 18 with pyrotechnic bolts or similar release mechanism. 
Motors 20 drive pinion gears 16 through ring gear 14 and rotate structure 
12 and the satellite until the satellite is rotating at a selected angular 
velocity. The satellite is then released from contact with rotating 
structure 12 to continue its rotational movement separate from the booster 
rocket. 
Referring to FIG. 2, a partial sectional view of spin table 22 known in the 
prior art is shown. Spin table 22 generally comprises stationary base 24, 
bearing 26, off-load spring 28, and rotating structure or frame 30. 
Structure or frame 30 is releasably attached to a satellite (not shown) 
and is rotated by ring gear 32 driven by a pinion gear and motor (not 
shown). Initially, the satellite is lifted to the desired elevation while 
frame 30 is fixed in contact with base 24. This fixed position between 
frame 30 and base 24 limits potential damage to such components and to 
bearing 26 during transport of the satellite. After the satellite is 
raised to the desired elevation, the connection between frame 30 and base 
24 is removed, and off-load spring 28 urges frame 30 away from base 24 to 
create gap 34. In such position, gap 34 permits sufficient clearance to 
permit frame 30 to rotate around base 24. 
The prior art apparatus illustrated in FIG. 2 is difficult to operate for 
several reasons. Off-load spring 28 functions as a large Belleville spring 
and requires careful manufacturing tolerances and specifications. For 
example, the failure to properly heat treat the off-load spring during 
manufacture can significantly affect the size of the gap created when the 
mechanism is operated. If the gap is too small, there is a possibility of 
friction between frame 30 and base 24 which would adversely affect the 
rotation of the satellite. If the gap is too large, the stability of frame 
30 under rotation can be adversely affected, and undesirable bending 
moments can act on bearing 26. In addition, the extreme thermal variations 
experienced between a terrestrial and an extraterrestrial environment can 
significantly affect the performance of off-load spring 28. 
The utility of off-load spring 28 is further encumbered by the need to test 
spin table 22 in an environment subject to gravitational acceleration. To 
properly test the operation of spin table 22, an object which approximates 
the size and mass of the satellite or other payload must be rotated to 
verify the operation of spin table 22 and bearing 26. During such test 
procedures, a mechanism simulates a zero gravity environment by uplifting 
the weight of the test payload from off-load spring 22 without affecting 
the inertial mass of the test payload as it experiences the rotational 
force of spin table 22. For test payloads weighing six tons and having a 
center of gravity ten feet above spin table 22, the task of simulating an 
accurate test environment can be difficult. 
FIG. 3 illustrates one embodiment of the present invention as it relates to 
a spin table for rotating a satellite (not shown). As shown in FIG. 3, a 
partial sectional view of spin table 36 is shown. Stationary base 38 is 
attached to a rocket booster or other vehicle (not shown) used for 
transporting a satellite or other payload to a selected elevation. Frame 
40 is rotatable about base 38 and is separated from base 38 with gap 42. 
Bearing 44 retains base 38 and frame 40 in engagement which permits frame 
40 to rotate about base 38. Bearing 44 includes mounting flanges 46. 
Bearing 44 is rigidly attached to base 38 with threaded bolt 48 or other 
fastening device, and is attached to frame 40 with threaded bolt 50 or 
other fastening device. Ring gear 52 is also attached to frame 40 and is 
mated with a pinion gear or other drive (not shown) capable of rotating 
ring gear 52 and attached frame 40 about base 38 similar to the spin table 
shown in FIG. 1. 
As illustrated in FIG. 3, clamp 54 is capable of contacting base 38 and 
frame 40 to prevent relative movement between base 38 and frame 40. Clamp 
54 can be manufactured from a metal such as aluminum or from any plastic 
or similar material capable of contacting base 38 and frame 40 through 
frictional contact, or through structural engagement such as with ribs or 
similar protrusions or recesses in clamp 54. Clamp 54 also acts to dampen 
vibrational forces acting on base 38 and frame 40 during transport. 
Tensioner 56 is illustrated as a band capable of urging clamp 54 into 
contact with base 38 and frame 40. In one embodiment of the invention, 
tensioner 56 can comprise a metallic band having two ends (not shown). A 
release mechanism such as bolt 58 can operate tensioner 56 to remove clamp 
54 from contact with base 38 and frame 40. In one embodiment of the 
invention, bolt 58 can comprise a pyrotechnic bolt, of the type known in 
the art, which initially draws two ends of tensioner 56 together to urge 
clamp 54 into contact with base 38 and frame 40, and then is removed by 
physical or electrical means to operate tensioner 56 to remove clamp 54 
from contact with base 38 and frame 40. 
One embodiment of clamp 54 is shown in FIG. 3. In this embodiment, clamp 54 
is shown as a "W" band having beveled clamp surfaces 60 in contact with 
beveled surfaces 62 of base 38, and having beveled clamp surfaces 64 in 
contact with beveled surfaces 66 of frame 40. In this embodiment, clamp 54 
includes protrusion 70 and surfaces 60 and 64 which contact base 38 and 
frame 40 to prevent relative movement therebetween. In addition, 
protrusion 70 prevents this relative movement while maintaining the 
selected dimension of gap 42. When release 58 operates tensioner 56 to 
remove clamp 54 from contact with base 38 and frame 40, gap 42 exists 
without any further manipulation or movement of the system, and permits 
relative movement between frame 40 relative to base 38. In the embodiment 
of the invention shown in FIG. 3, gap 42 permits rotation of frame 40 
about base 38. 
The configuration and orientation of clamp 54 can be modified without 
departing from the scope of the invention. For example, the contacting 
surface of clamp 54 can be configured as a "V" or as a flat, circular, or 
other shape appropriate to engage the shape of base 38 and frame 40. The 
contacting surface of clamp 54 can further be designed to adjust the size 
of gap 42 under clamping engagement, or to maintain the size of gap 42 
under clamping engagement. In other embodiments of the invention, clamp 54 
can engage base 38 and frame 40 through physical contact rather than 
through frictional contact. For example, the contacting surface of clamp 
54 can be grooved or punctuated with projections or recesses which 
physically engage base 38 and frame 40 to prevent relative movement 
therebetween. In one embodiment, the surface of clamp 54 could include 
projections similar to the teeth of a gear which contact with opposed 
recesses in base 38 and frame 40. While the contact between clamp 54 and 
base 38 and frame 40 does not need to be a entirely rigid connection, such 
contact should be sufficiently strong to survive acceleration forces 
acting on the system during the transport of the system. 
The invention significantly reduces the complexity and weight of existing 
retaining mechanisms, and reduces the forces acting on bearing 44. By 
rigidly connecting bearing 44 to base 38 and frame 40 as shown, movement 
of bearing 44 is controlled, and potential moments acting on bearing 44 
are reduced. This is important because launch weight considerations may 
reduce the desired size of the system components such as bearing 44. 
Typically, smaller components are not as strong as larger structural 
components, and the designer must balance the competing parameters of 
weight and necessary strength. In addition, the virtual elimination of 
adjustable parts necessary to move frame 40 from a fixed position to a 
floating position relative to base 38 reduces flexure of the system which 
can be transferred as bending moments to bearing 44, and therefore reduces 
the possibility of bearing failure during transport. Furthermore, the 
unique use of clamp 54 isolates bearing 44 from experiencing structural 
loading or bending moment forces during transport, such as in the launch 
phase of the vehicle. Clamp 54 accomplishes this task by creating a load 
path for forces directly from frame 40 through clamp 54 to base 38. This 
load path during transport permits bearing 44 to be downsized to the 
forces experienced in a zero gravity environment, which reduces the weight 
and cost of the system. 
Thus it can be seen that the present invention provides many advantages 
over the prior art by providing a system for releasably restraining a 
first element and a second element which are separated by a gap. The 
invention allows reduction in the weight and complexity of the system, 
which improves manufacturing efficiency and reduces the quantity of fuel 
necessary to transport the entire system. The containment of the first and 
second elements is accomplished by transferring the restraining load 
through the clamping mechanism, which isolates sensitive bearings and 
other components from transport forces. In addition, the release of the 
clamping mechanism can be accomplished without moving or adjusting either 
the first element or the second element, or any bearings which engage 
these elements. The invention also facilitates the ground testing of the 
system because of the absence of moving components which are designed to 
operate in a zero gravity environment, but are tested in the presence of a 
gravitational field. Consequently, the ease of testing and the test 
accuracy of the system is enhanced by the present invention. 
Although the present invention has been described in terms of certain 
preferred embodiments, it will be apparent to those of ordinary skill in 
the art that various modifications can be made without departing from the 
scope of the inventive concepts. The embodiments shown herein are merely 
illustrative of the inventive concepts and should not be interpreted as 
limiting the scope of the inventive concepts.