FINELY ADJUSTABLE STEADY REST SYSTEM

Abstract

A steady rest has working and right-hand cover plates and a central plate sandwiched therebetween. The working cover plate has upper and lower guide tracks that are received within cavities. The central plate is movably disposed between the working and right-hand cover plates. The central plate slidably engages upper and lower gripping arms that are movable relative to the working cover plate between a clamped position and a retracted position. Tapered rails are disposed in a rail recess of the working cover plate. The rails are movable relative to each other to finely and precisely adjust a position at which the workpiece is clamped and moved horizontally or vertically when the gripping arms are in the clamped position.

Claims

1. A steady rest for gripping and finely positioning a workpiece, the steady rest comprising: a working cover plate and a right-hand cover plate, a central plate disposed between the working and right-hand cover plates, the central plate being adapted to move slidably therebetween, the central plate having an upper and a lower cross-channel for engaging upper and lower gripping arms, the gripping arms being movable relative to the working and right-hand cover plates between a clamped position and a retracted position, the central plate also having a rail recess and a pair of cavities that respectively receive upper and lower guide tracks; a tapered horizontal rail situated in the rail recess that is adapted to cause displacement of the workpiece horizontally; a vertical rail with a flat face that abuts the horizontal rail and an opposing face with inclined sections the meet on opposing sides of a flat middle section, the vertical rail being adapted to move the workpiece vertically, the horizontal and vertical rails being received in the rail recess, the horizontal and vertical rails contacting the rail recess and each other while controlling location of the gripping arms, the horizontal and vertical rails being movable relative to each other within the rail recess to adjust a position relative to the working and right-hand cover plates at which the workpiece will be clamped when the upper and lower gripping arms are in the clamped position.

2. The steady rest of claim 1, further comprising horizontal and vertical threaded adjustment rods threadably received in apertures of the working cover plate and extending into the rail recess, the horizontal threaded adjustment rod abutting the horizontal rail and being rotatable to adjust a position of the horizontal rail, the vertical threaded adjustment rod abutting the vertical rail and being rotatable to adjust a position of the vertical rail.

3. The steady rest of claim 2, further comprising engagement springs for biasing the horizontal and vertical rails into contact with an upper wall of the rail recess.

4. The steady rest of claim 1, wherein the vertical rail includes a flat side that slidingly engages the horizontal rail and an opposing side wherein the inclined sections have faces that are inclined thereto by an angle theta, where theta lies between 0.92 and 1.08 degrees.

5. The steady rest of claim 1, wherein the horizontal rail includes a flat side that slidingly engages the vertical rail and an opposing side that slidingly engages a wall of the rail recess, wherein the flat side and the wall are inclined by an angle theta, where theta lies between 0.92 and 1.08 degrees.

6. The steady rest of claim 1, wherein the upper and lower gripping arms include pins extending therefrom that are slidably received in upper and lower guide tracks located in the cavity of the working cover plate.

7. The steady rest of claim 6, wherein the upper and lower guide tracks each have an elongated leg and a shorter leg extending therefrom.

8. The steady rest of claim 1, further including an actuation mechanism with a housing having fluid chambers, a piston positioned between the chambers and a ramrod, the housing being secured to the working cover plate and/or the right-hand cover plate.

9. The steady rest of claim 8, wherein the housing and the piston define fluid chambers in communication with upper and lower ports respectively, the ports being in fluid communication with a source of working fluid and a fluid control device that is operable to control a flow of the working fluid in and out of the ports.

10. The steady rest of claim 1, wherein a 90 degree turn of a vertical or horizontal adjustment rod displaces a gripped workpiece by 1 micron while holding the workpiece in place, despite forces exerted by machining operations and by the spinning mass of the workpiece.

11. A method of moving the steady rest of claim 1 from a retracted position to a clamped position, comprising the steps of injecting a working fluid is injected into a chamber of an actuation mechanism and evacuating at least some working fluid) from the chamber, thereby causing a piston to move toward the workpiece; moving the central plate with the piston along an axis relative to the working plate and the right-hand plate; as the central plate and gripping arms move toward the clamped position, sliding pins and bushings along the legs of corresponding guide tracks so that the bushings come into contact with surfaces of the guide tracks and so that the pins and bushings slide laterally outwardly along lower legs of the guide tracks, the protruding ends of the gripping arms thereby moving toward each other to come into contact with and securely clamp the workpiece.

12. A method of moving a clamped workpiece horizontally using the steady rest of claim 1, comprising the steps of rotating a horizontal adjustment rod in a direction that causes movement of the horizontal rail under the influence of an engagement springs, such movement occurring under the constraint of an angle of inclination (theta, about 0.92 to 1.08 degree) between the horizontal rail and a wall of the rail recess so that a wedge effect influences and constrains movement of the guide tracks that abut the rail; and moving the horizontal guide rail upwardly under the influence of an associated engagement spring so that a position along the guide tracks at which bushings contact the guide tracks also moves outwardly, thereby displacing the workpiece horizontally, so that rotation of one or both adjustment screws move a clamped workpiece inwardly or outwardly.

13. A method of moving a clamped workpiece vertically using the steady rest of claim 1, comprising the steps of rotating a vertical adjustment rod in a direction that causes movement of the vertical rail under the influence of an engagement springs, such movement occurring under the constraint of an angle of inclination (theta, about 0.92 to 1.08 degree) between vertical rail and a wall of the rail recess so that a wedge effect influences and constrains movement of the guide tracks that abut the rail; and moving the vertical rail upwardly under the influence of an associated engagement spring so that a position along the guide tracks at which bushings contact the guide tracks also moves vertically, thereby displacing the workpiece vertically.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The drawings described herein are for illustrative purposes of selected embodiments and not all possible implementations. They are not intended to limit the scope of the present disclosure.

[0012] FIG. 1 is a perspective, exploded view of part of an adjustable steady rest system with a right hand cover plate removed for clarity;

[0013] FIG. 2 is a laid open, exploded view of the steady rest system;

[0014] in FIG. 3B;

[0015] FIG. 3A is a vertical, sectional view of the steady rest system along the line B-B in FIG 3B;

[0016] FIG. 3B is a vertical, sectional view of the steady rest system with the right-hand cover plate removed;

[0017] FIGS. 4A and 4B illustrate various components in vertical adjustment modes;

[0018] FIGS. 5A and 5B illustrate various components in horizontal adjustment modes;

[0019] FIG. 6 further illustrates horizontal displacement of a clamped workpiece in response to turning an adjustment screw; and

[0020] FIG. 7 further illustrates vertical displacement of a clamped workpiece in response to turning another adjustment screw.

[0021] Corresponding reference numerals indicate corresponding parts throughout the several drawings.

DETAILED DESCRIPTION

[0022] Representative embodiments will now be described more fully with reference to the accompanying drawings.

[0023] Components of a Representative Steady Rest System

[0024] With reference to FIGS. 1-7, in one embodiment, an adjustable steady rest system (hereinafter “steady rest”) 10 is provided that is adapted to clamp and if desired, finely adjust the position of a workpiece 12 during a machining operation (e.g., grinding or turning) by horizontal or vertical displacement. In one embodiment, the steady rest 10 preferably includes a working cover plate 14, a right-hand cover plate 16 (from the perspective of FIG. 3A), and a central plate 18 that is sandwiched between them.

[0025] The steady rest 10 is adapted to cause gripping and displacement of the workpiece 12 vertically (FIGS. 4A, 4B and 7), or horizontally (FIGS. 5A, 5B and 6).

[0026] Upper and lower gripping arms 20, 22(FIG. 1) and a cylinder/piston actuation mechanism 24 (FIG. 2) are provided. As will be described in more detail below, the actuation mechanism 24 is operable to move the central plate 18 and the gripping arms 20, 22 between a clamped position, in which the steady rest 10 grips the workpiece 12, and a retracted position, in which the workpiece 12 is released and the gripping arms 20, 22 are retracted into the steady rest 10.

[0027] The working cover plate 14 is a generally solid, flat plate having a plurality of threaded and unthreaded mounting apertures 32 (FIG. 2). Upper and lower slide plates 28, 30 (FIG. 1) are mounted (directly or indirectly) to the working cover plate 14. The central plate 18 is adapted to slide between the slide plates 28, 30. The upper and lower slide plates 28, 30 include threaded and/or unthreaded apertures 32 aligned with the apertures 26 in the working cover plate 14.

[0028] The right-hand cover plate 16 (FIG. 3A) has apertures that are aligned with the apertures 32 of the slide plates 28, 30 and with the apertures 26 of the working cover plate 14. Bolts 40 or other fasteners are received in some or all of the apertures to fixedly secure the working and right-hand cover plates 14, 16 to each other and to the slide plates 28, 30. The central plate 18 is sandwiched therebetween (as shown in FIGS. 1 and 3), and is movable horizontally between the side plates 28,30.

[0029] The working and right-hand cover plates 14, 16 and the slide plates 28, 30 cooperate to define a cavity 43 in which guide tracks 44, 46 are movably received. The guide tracks 44,46 are adapted to move horizontally under the influence of engagement springs 42 (FIG. 1).

[0030] As shown in FIGS. 1-2, the working cover plate 14 accommodates the upper and lower guide tracks 44, 46 that are received in the cavities 43 (FIG. 1). Each of the guide tracks 44, 46 preferably includes an elongated leg 50 and a relatively shorter leg 52 (FIG. 2). The legs 50 of the upper and lower guide tracks 44, 46 preferably extend parallel to each other and parallel to a longitudinal axis −X (FIG. 6). Each of the shorter legs 52 extends from an end of a corresponding one of the longer legs 50 in a direction that is laterally outward and away from the workpiece 12 (i.e., an acute angle is formed between the longer and shorter legs 50, 52).

[0031] To displace the gripping arms 20, 22 and thus a clamped workpiece 12 in precise, predictable and finely metered amounts, a number of components cooperate to displace a workpiece vertically (FIGS. 4A, 4B and 7) and horizontally (FIGS. 5A, 5B and 6).

[0032] Shaped rails 58, 60 (FIG. 1) respectively cooperate to finely displace a workpiece 12 vertically and horizontally with predictable precision in a manner to be described. These rails are slidingly movable within a rail recess 48 independently of each other (see, e.g., FIGS. 2-7). The vertical rail 58 has a flat face 70 (enlargement, FIG. 7) that abuts the horizontal rail and an opposing face with inclined sections 62, 64 that meet on opposing sides of a flat middle section.

[0033] The working cover plate 14 has threaded apertures 92, 94 (FIG. 1) that extend perpendicularly to the longitudinal axis X-X and communicate with the rail recess 48 (FIG. 2). Adjustment screws or rods 96, 98 (FIGS. 2, 6-7) threadably engage the threaded apertures 92, 94, respectively, and extend into the rail recess 48. Preferably, about 100 threads per inch are provided to enable finely tuned adjustments to be made. An end of the upper or vertical adjustment rod 98 abuts an end of the rail 58 which adjusts the workpiece position minutely vertically (“vertical rail 58”). An end 100 of the lower or horizontal adjustment rod 96 abuts an end of the rail 60 (FIG. 5A), which finely tunes the workpiece position horizontally (“horizontal rail” 60).

[0034] Engagement springs 104 are positioned between a lower wall 106 of the rail recess 48 and a corresponding one of the vertical and horizontal rails 58, 60 (FIGS. 4A, 4B, 5A and 5B). The springs 104 bias the rails 58, 60 into contact with the axial ends 100, 102 of the adjustment rods 96, 98. In this manner, the rails 58, 60 move toward and away from the lower wall 106 (in the directions shown in FIGS. 4-5) as the adjustment rods 96, 98 are moved along the threaded apertures 92, 94 into and out of the rail recess 48.

[0035] Threadably adjusting the position of the horizontal adjustment rod 96 (FIGS. 5A, 5B and 6) causes the horizontal rail 60 to slide in relation to the wall of the rail recess 48. There is a relative angle (theta) between the wall and the side 72 of the horizontal rail 60 (FIG. 5A and enlargement, FIG. 5B). Thus, movement of the horizontal rail 60 along the wall 56 causes corresponding movement of the vertical rail 58 toward or away from the wall 56 in a direction along or parallel to the longitudinal X-axis.

[0036] Threadingly adjusting the position of the vertical adjustment rod 98 (FIGS. 4A, 4B and 7) causes the vertical rail 58 to slide in relation to the wall 70 of the horizontal rail 60. There is a relative angle (theta) between the walls 62, 64 of the vertical rail 58 and walls 45, 47 of the guide tracks 44, 46 (enlargement, FIG. 4B). Thus, movement of the vertical rail 58 along the wall 70 causes opposing movement of the guide tracks 44, 46 toward and away from the wall 70 in a direction along or parallel to the longitudinal axis.

[0037] Cross channels 112, 114 (FIGS. 2, 3A and 3B) formed in the central plate 18 slidingly receive the gripping arms 20, 22. The upper channel 112 receives the upper arm 20. The lower channel 114 receives the lower arm 22. A slot 116 extends into the upper channel 112. A longitudinal axis of the slot 116 extends parallel to a longitudinal axis of the upper channel 112. Similarly for a slot provided in the lower channel 114. The upper and lower channels 112, 114 are angled relative to the longitudinal axes and to each other. The upper and lower channels 112, 114 cross each other to form a generally X-shaped pattern. The channels 112, 114 are configured so that the upper and lower gripping arms 20, 22 may move without interfering with each other. As will be described in more detail below, the upper gripping arm 20 is slidably received in the upper channel 112, and the lower gripping arm 22 is slidably received in the lower channel 114.

[0038] A gripping finger 118 extends from the central plate 18 between the upper and lower channels 112, 114 (FIG. 3B). The gripping finger 118 cooperates with gripping fingers 119 of the upper and lower gripping arms 20, 22 to grip and finely displace the workpiece 12 when the steady rest 10 is in the clamped position (FIGS. 4-7).

[0039] Another end of the central plate 18 has a generally T-shaped aperture 124. As shown in FIG. 3B, the T-shaped aperture 124 receives a similarly shaped end 126 of a ramrod 128 of the actuation mechanism 24.

[0040] Each of the upper and lower gripping arms 20, 22 is preferably provided with an elongated upper portion 130 and a relatively shorter lower portion 132 (FIG. 2). The upper and lower portions 130, 132 preferably are angled relative to each other. The gripping fingers 119 extend toward each other from the lower portions 130, 132.

[0041] The upper portions 130 of the gripping arms 20, 22 include pins or roller guides 134, 135 that protrude therefrom and extend into a corresponding one of the upper and lower guide tracks 44, 46. As shown in FIG. 2, pin 134 of the upper gripping arm 20 extends through slot 116 and into the lower guide track 46. In this way, an axial end of the pin 134 slidably engages the groove 54 of the lower guide track 46. The pin 135 of the lower gripping arm 22 extends into the upper guide track 44. An axial end of the pin 135 slidably engages the groove 54 of the upper guide track 44. The pins 134, 135 have bushings 140, 142 that are slidably received in the lower and upper guide tracks 46, 44, respectively (FIG. 3B).

[0042] Turning now to FIGS. 2 and 3B, the actuation mechanism 24 includes a housing 144 with a chamber 148, a piston 146 and a ramrod 128. The housing 144 has a flange 145 that is bolted or otherwise mounted to the working cover plate 14 and/or the right-hand cover plate 16. The housing 144 and the piston 146 define fluid chambers 148, 150 in communication with upper and lower ports 152, 154, respectively (FIG. 2). The piston 146 is attached to the ramrod 128 and separates the fluid chambers 148, 150. The ports 152, 154 are in fluid communication with a source of working fluid (e.g., compressed air or preferably, hydraulic fluid). A fluid control device (not shown) is operable to control a flow of the working fluid in and out of the ports 152, 154.

[0043] To move the piston 146 and ramrod 128 away from the workpiece 12, the control device causes working fluid to flow into the fluid chamber 150 while evacuating fluid from the other fluid chamber 148. To move the piston 146 and ramrod 128 toward the workpiece 12, the control device causes working fluid to flow into fluid chamber 148 while evacuating fluid from the chamber 150. Because the ramrod 128 is connected to the central plate 18, movement of the piston 146 and ramrod 128 toward and away from the workpiece 12 causes corresponding movement of the central plate 18 toward and away from the workpiece 12.

[0044] While the actuation mechanism 24 is described above as being a fluid-actuated device, it will be appreciated that any type of actuator could be used (e.g., an electric motor or other electromechanical device). Preferably the fluid is a liquid.

[0045] In conventional steady rests, threaded (tapped) holes are provided directly into the working and right-hand cover plates 14, 16. If the threads become damaged, the cover plates themselves are often needed to be replaced. Such an operation involves down-time and related cost. But with the steady rests systems disclosed herein, most repairs (if needed) are limited to replacement of the horizontal and/or threaded adjustment rods 96, 98 and associated locking nuts, the brass block in which receiving apertures are defined, roller bearings or bushings 140, 142, and seals in the cylinder 24. Such steps are economically advantageous in comparison to prior approaches.

[0046] As described herein, the vertical threaded adjustment rod 98 lies on the left side (from the perspective of FIG. 1). In alternative embodiments, the vertical threaded adjustment rod 98 and related components may lie on the right side.

[0047] Operation of a Representative Steady Rest System

[0048] (a) Clamping and Releasing the Workpiece

[0049] With continued reference to FIGS. 1-7, operation of a representative embodiment of a steady rest system 10 will now be discussed. As described above, the actuation mechanism 24 is operable to move the central plate 18 and the gripping arms 20, 22 between a clamped position, in which the steady rest 10 grips the workpiece 12 and a retracted position, in which the workpiece 12 is released and the gripping arms 20, 22 are retracted into the steady rest 10.

[0050] The steady rest 10 can be finely, precisely and predictably adjusted to move the position of the workpiece 12 relative to the steady rest 10 when the workpiece 12 is in the clamped position (see FIGS. 4-7). For example, a 90 degree turn of a vertical or horizontal adjustment rod 96, 98 can displace a gripped workpiece by 1 micron while holding the workpiece in place, despite forces exerted by machining operations and by the spinning mass of the workpiece. Such precision was not possible in conventional steady rests.

[0051] To move the steady rest 10 from the retracted position to the clamped position, working fluid is injected into chamber 148 of the actuation mechanism 24 and working fluid (if present) is evacuated from chamber 150 (FIG. 2). This causes the piston 146 and the ramrod 128 to move toward the workpiece 12 (i.e., to the right relative to the frame of reference of FIG. 3B).

[0052] The central plate 18 moves with the ramrod 128 along the longitudinal X-axis relative to the working plate 14 and the right-hand plate 16. As the central plate 18 and gripping arms 20, 22 move toward the clamped position, the pins 134, 135 and bushings 140, 142 slide along the legs 50 of the corresponding guide tracks 44, 46. Continued movement of the ramrod 128 and central plate 18 along the longitudinal X-axis toward the workpiece 12 causes the bushings 140, 142 to come into contact with the surfaces 49, 51 respectively, of the guide tracks 44, 46 (FIG. 5B).

[0053] Preferably, the rails 58, 60 engage each other under the influence of a sliding interference fit. In one embodiment, there is about a 1 degree inclination of face 64 and surface 47 and face 62 and surface 45 (enlargement, FIG. 7). Correspondingly there is about a 1 degree inclination between face 56 and surface 72.

[0054] Once the bushings 142, 140 are in contact with the guide tracks 44, 46 and thus the surfaces 62, 64 (FIGS. 4A and 7) of the vertical rail 58, continued movement of the ramrod 128 and central plate 18 along the longitudinal X-axis toward the workpiece 12 causes the pins 134, 135 (FIG. 2) and bushings 140, 142 to slide laterally outwardly along the lower legs 52 of the guide tracks 44, 46. As the roller guides 134, 135 and bushings 140, 142 slide laterally outwardly along the lower legs 52 of the guide tracks 44, 46, the protruding ends (i.e., the lower portions 132) of the gripping arms 20, 22 move toward each other. The direction of movement is in a direction perpendicular to the longitudinal X-axis. The gripping arms 20, 22 slide in the channels 112, 114, respectively, relative to the central plate 18 until the gripping fingers 119 of the gripping arms 20, 22 and the gripping finger 118 of the central plate 18 come into contact with and securely clamp the workpiece 12.

[0055] To move the steady rest 10 from the clamped position to the retracted position (FIG. 7), working fluid is injected into the chamber 150 of the actuation mechanism 24 and working fluid (if present) is evacuated from the other chamber 148. This causes the piston 146, the ramrod 128 and the central plate 18 to move relative to the working and right-hand cover plates 14, 16 away from the workpiece 12 after releasing it. Such movement reverses the movement of the gripping arms 20, 22 described above.

[0056] (b) Displacing the Workpiece Horizontally and Vertically

[0057] Turning now to FIGS. 4-7, the adjustment rods (fine screws, with about 100 threads per inch) 96, 98 can be turned to finely shift the position in which the clamped workpiece 12 will be moved by the gripping fingers 118, 119.

[0058] As shown in FIG. 6, to move the workpiece 12 horizontally toward the working and right-hand cover plates 14, 16, the user rotates the horizontal adjustment rod 96 in a direction that causes movement of the horizontal rail 60. Such movement occurs within the recess 48 in a direction perpendicular to the longitudinal X-axis. Engagement springs 90 urge the rails 96, 98 upwardly.

[0059] There is a fine angle of inclination (theta, about 0.92 to 1.08 degrees, preferably 1.00 degree) between the horizontal rail 60 and the wall of the recess 48. As a result, a wedge effect is created that influences and constrains movement of the guide tracks 44, 46 that abut the rail 58.

[0060] By moving the horizontal guide rail 60 upwardly under the influence of an associated engagement spring 90 (FIGS. 5B, 6), the position along the guide tracks 44, 46 at which the bushings 140, 142 contact the guide tracks 44, 46 also moves outwardly.

[0061] FIGS. 6-7 schematically illustrate how rotation of one or both adjustment screws 96, 98 move a clamped workpiece inwardly or outwardly (FIG. 6) and/or upwardly and downwardly (FIG. 7).

[0062] For example, to move the position in which the gripping fingers 118, 119 precisely move the workpiece 12 in a vertical direction, the user rotates the adjustment rod 98. In one case, clockwise displacement of 90 degrees raises the workpiece 12 by 1 micron. Conversely, counterclockwise displacement lowers the workpiece by a corresponding amount.

[0063] It will be appreciated that intermediate adjustments may be made, and that displacement is not limited to 90 degree increments or decrements.

[0064] The steady rest 10 may be used to hold the workpiece 12 for a grinding operation. It will be appreciated, however, that the principles of the present disclosure may be applicable to steady rests configured for turning operations and/or other machining or manufacturing operations.

[0065] The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.

REFERENCE LIST

[0066] 10 Steady rest system [0067] 12 Workpiece [0068] 14 Working cover plate [0069] 16 Right hand cover plate [0070] 18 Central plate [0071] 20 Upper gripping arm [0072] 22 Lower gripping arm [0073] 24 Actuation mechanism [0074] 26 Apertures [0075] 28 Upper slide plate [0076] 30 Lower slide plate [0077] 32 Aperture [0078] 40 Bolt [0079] 42 Engagement spring [0080] 43 Cavity [0081] 44 Upper guide track [0082] 45 Side wall, upper track [0083] 46 Lower guide track [0084] 47 Side wall of lower track [0085] 48 Rail recess [0086] 49 Inner wall of upper guide track [0087] 50 Elongated upper leg [0088] 52 Inner wall of lower guide track [0089] 52 Shorter lower leg [0090] 54 Groove [0091] 56 Upper wall [0092] 58 Vertical rail [0093] 60 Horizontal rail [0094] 62 Upper side of vertical rail [0095] 64 Lower side of vertical rail [0096] 70 Upper side of horizontal rail [0097] 72 Lower side of horizontal rail [0098] 90 Spring [0099] 92 Threaded aperture [0100] 94 Threaded aperture [0101] 96 Horizontal threaded adjustment rod [0102] 98 Vertical threaded adjustment rod [0103] 100 Axial end of 96 [0104] 102 Axial end of 98 [0105] 104 Pair of springs [0106] 106 Second wall of 48 [0107] 108 First side of 18 [0108] 110 Second side of 18 [0109] 112 Upper cross channel [0110] 114 Lower cross channel [0111] 116 Slot [0112] 118 Gripping finger [0113] 119 Gripping finger arm [0114] 124 T-shaped aperture [0115] 126 T-shaped end of 128 [0116] 128 Ramrod of 24 [0117] 130 Elongated first portion of gripping arms [0118] 132 Shorter second portion of griping arms [0119] 134 Pin [0120] 135 Pin [0121] 140 Bushing [0122] 142 Bushing [0123] 144 Housing [0124] 145 Flange [0125] 146 Piston [0126] 148 First fluid chamber [0127] 150 Second fluid chamber [0128] 152 Port [0129] 154 Port