Patent Publication Number: US-2015083981-A1

Title: Concentric slave cylinder removal tool

Description:
FIELD 
     The present disclosure relates to a tool for repair or removal of a concentric slave cylinder from a vehicle transmission. 
     BACKGROUND 
     Certain transmissions include a hydraulic piston assembly, such as a concentric slave cylinder, that is accessible from the exterior of the transmission, and may be mounted to the exterior of the transmission case. The piston assembly may include a piston rod that extends into an interior of the transmission and is coupled to a clutch mechanism of the transmission and is operable to actuate the clutch mechanism. The piston rod also is coupled to a piston of the piston assembly mounted to the transmission. Accordingly, repair of the piston assembly has required the transmission to be removed from the vehicle to prevent damage to the clutch mechanism that may be caused by undue movement of the piston rod, this is costly and time consuming. Likewise, damaging the transmission during the piston assembly repair is also costly. 
     SUMMARY 
     In at least one implementation, a tool for a transmission piston assembly having a housing mounted to a transmission case includes a base plate, a reaction member, a connection member and an actuator. The reaction member is fixed in place relative to the transmission case and the connection member is adapted to interconnect the base plate to the housing of the piston assembly. The actuator is adapted to engage the reaction bar and displace the base plate relative to the reaction member to displace the housing relative to the transmission case. In at least some implementations, the amount of movement of the piston assembly may be limited to a threshold or less to prevent damage to the transmission. The actuator, base plate and/or reaction member may be constructed and arranged to provide a stop that ensures the threshold amount of movement is not exceeded. 
     A clamp for a piston rod may be coupled to a piston of a piston assembly that is coupled to a transmission case. The clamp may include a pair of clamp bodies each having a first surface and a second surface opposite the first surface, and a clamp surface defined in a protrusion that extends from the second surface such that the clamp surface is offset from the second surface. The protrusion is adapted to be at least partially received into an opening of a transmission case in which the piston rod is received. The protrusion may enable the clamp surface to extend away from a main body or support surface of the clamp and enable the clamp surface to engage a piston rod at a location at least partially beneath an outer surface of the transmission case, and/or permit the clamp surface to remain clear of a piston connected to the piston rod. 
     In at least some implementations, a tool is provided for a transmission piston assembly that has a housing mounted to a transmission case The tool includes a base plate, a reaction member, a base plate support, a piston actuator and an actuator. The reaction member has at least one support by which the reaction member is fixed in place relative to the transmission case. A connection member interconnects the base plate to the housing of the piston assembly. The base plate support is adapted to engage the base plate and the piston assembly housing to limit movement of the piston assembly housing toward the base plate. The piston actuator has a piston engaging feature adapted to displace a piston of the piston assembly relative to the housing when the tool is connected to the piston assembly. And the actuator is adapted to engage the reaction bar and displace the base plate relative to the reaction member to displace the housing relative to the transmission case. In this way, the piston assembly can reliably, controllably and repeatably be moved away from the transmission case to facilitate repair or replacement of the piston assembly. 
     In some forms, the piston assembly may include a piston coupled to a piston rod and lifting the piston assembly off the transmission case may provide access to the piston rod to permit it to be decoupled from the piston. The tool may also include a piston rod clamp used to decouple the piston rod and piston, or the clamp may be considered to be a separate component. Once decoupled, the remainder of the piston assembly can be entirely removed from the transmission without having to remove the piston rod and without damaging the transmission. Further, in at least some forms, this can be accomplished without having to remove the transmission from the vehicle resulting in much easier and less expensive repair of the piston assembly and transmission. 
     Further areas of applicability of the present disclosure will become apparent from the detailed description, claims and drawings provided hereinafter. It should be understood that the summary and detailed description, including the disclosed embodiments and drawings, are merely exemplary in nature intended for purposes of illustration only and are not intended to limit the scope of the invention, its application or use. Thus, variations that do not depart from the gist of the disclosure are intended to be within the scope of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a slave cylinder puller tool; 
         FIG. 2  is a plan view of the slave cylinder puller tool and a piston rod clamp used to remove the slave cylinder piston assembly from the transmission; 
         FIG. 3  is a fragmentary side view showing the puller tool mounted on a slave cylinder that is mounted to the transmission; 
         FIG. 4  is a view similar to  FIG. 3  showing the slave cylinder moved away from the transmission and coupled with a piston rod; 
         FIG. 5  is a sectional view showing a piston rod clamp coupled to the piston rod to permit the piston assembly to be removed from the piston rod; 
         FIG. 6  is a plan view of a cross bar of the puller tool; 
         FIG. 7  is a side view of the cross bar; 
         FIG. 8  is a side view of an engagement arm of the puller tool; 
         FIG. 9  is a plan view of the piston rod clamp; and 
         FIG. 10  is a side view of one part of the piston rod clamp showing a piston rod engagement surface. 
     
    
    
     DETAILED DESCRIPTION 
     Referring in more detail to the drawings,  FIGS. 1-5  illustrate a puller tool  10  and a piston rod clamp  12  that may be used to remove a piston assembly  14  of a concentric slave cylinder  16  from a vehicle transmission  18 . The slave cylinder piston assembly  14  may be mounted to an exterior of the transmission  18 , or otherwise is accessible from an exterior of the transmission, and is coupled to a piston rod  20  that extends into the transmission  18 . The piston rod  20  is coupled to a transmission clutch and actuates the clutch in response to actuation of the piston assembly  14 , in known manner. Because the piston assembly  14  is connected to the piston rod  20 , the piston assembly  14  cannot simply be pulled off the transmission to repair or replace it. Doing so would cause the piston rod  20  to damage the clutch and require significant transmission repair. 
     To prevent damage to the clutch, the puller tool  10  permits and controls limited movement of the piston assembly  14  relative to the transmission  18 . The movement is within a given tolerance that is known to avoid damage to the clutch yet expose or provide access to at least a portion of the piston rod  20 . The piston rod clamp  12  may then be used to hold the piston rod  20  and permit removal of the piston assembly  14  from the piston rod  20 . Thereafter a repaired or replacement piston assembly can be connected to the piston rod  20  and the assembly reconnected to the transmission  18 . In at least some implementations, this can be accomplished while the transmission  18  is in place on the vehicle such that the transmission does not need to be disconnected from and reconnected to the vehicle. 
     In more detail, as shown in  FIGS. 3-5 , the piston assembly  14  may include a housing  22  having a mounting flange  24  that has openings  26  through which fasteners (e.g. bolts or machine screws) may extend to releasably secure the piston assembly  14  to a transmission case  28 . A seal  30  may be provided between the mounting flange  24  and the transmission case  28 . The piston assembly  14  may include a piston  32 , one or more seals  34 , and the housing  22  that may also include a dust/contaminant cover  36  for the piston. The piston  32  may include threads  38  that mate with threads on the piston rod  20  and a cylindrical support  40  in which a portion of the piston rod  20  extends. In use, the piston  32 , and hence the piston rod  20 , may be driven by hydraulic fluid in a pressure chamber defined between the piston  32  and the housing  22  (and one or more seals), and by a return spring  42  that may return the piston  32  to a home position absent hydraulic pressure acting on the piston. To remove the piston assembly  14  from the transmission, the bolts holding the mounting flange  24  to the transmission case  28  are removed and the puller tool  10  is connected to the piston assembly  14 . 
     As shown in  FIGS. 1-4 , the puller tool  10  includes a base plate  44 , a reaction member  46 , a piston actuator  48 , and one or more connection members  50  that couple the mounting flange  24  of the piston assembly  14  to the base plate  44  so that movement of the base plate  44  results in movement of the mounting flange  24 . The base plate  44  includes holes  52  generally aligned with the openings  26  in the mounting flange  24  and a threaded opening  54 . While shown as generally X-shaped, the base plate  44  could have any suitable shape. Support posts  56  may include reduced diameter ends that are received in two opposed holes  52  of the base plate  44  and opposite ends that may be received in corresponding openings  26  of the mounting flange  24 . The support posts  56  may be rigid and ensure a given separation between the base plate  44  and mounting flange  24 . 
     A connection member  50  may be provided in one or both of the remaining holes  52  in the base plate  44  such that the connection members extend into the corresponding or aligned openings  26  in the mounting flange  24 . In the implementation shown, for example in  FIGS. 3 ,  4  and  8 , the connection members  50  may include hooks  58  or bent ends that extend through the mounting flange openings  26 , and threaded opposite ends  60  that extend through the holes  52  in the base plate  44 . Nuts  62  may be secured to the threaded ends  60  to securely clamp the base plate  44  and mounting flange  24  on the support posts  56 , with the hooks  58  engaged with a lower surface  64  of the mounting flange  24 . The connection members  50  may be formed from a rigid material, like metal, and may be substantially inextensible. In this way, the base plate  44  and mounting flange  24  are securely connected together and movement of the base plate  44  will cause a corresponding movement of the mounting flange  24 . And the support posts  56  may provide additional stability to prevent canting, rocking or other movement of the piston assembly  14  relative to the base plate  44  to ensure controlled and repeatable movement of the piston assembly relative to the transmission  18 . 
     The reaction member  46  may be received between the base plate  44  and the piston assembly  14 . The reaction member  46  may be retained in position adjacent to the base plate  44  by one or more support posts  66 . At one end, the support posts  66  may be received in existing openings in the transmission case  28  (which openings may be threaded) and at their other end, the support posts  66  may bear on and be held against the reaction member  46 , such as by fasteners  68 . The support posts  66  may be rigid to hold the reaction member in place relative to the transmission case  28  under the forces applied to the puller tool  10 , as set forth herein. In one form the support posts  66  are formed from metal. The reaction member  46  may be defined by a rigid plate or bar of any suitable material and is shown as being formed from metal. The bar is shown as being rectangular, but could be of any desired shape and includes a portion that is aligned with the threaded opening  54  of the base plate  44 . A fastener  70  may be provided to connect the reaction member  46  with the base plate  44  to facilitate their handling and use as a single unit. Of course, this is only for convenience and they could be entirely separate, if desired. 
     As shown in  FIGS. 3 ,  4 ,  6  and  7 , the piston actuator  48  is disposed adjacent to the piston assembly  14  in use and includes a knob  72  or other protuberance that is adapted to engage the piston  32  within the piston assembly  14 . This may displace the piston  32  against its return spring  42  so that the force of the return spring  42  does not need to be overcome during removal of the piston assembly  14  as will be described later. A pair of openings  74  through the piston actuator  48  receive the base plate support posts  56  and thus, maintain the orientation of the piston actuator  48  relative to the base plate  44  and piston assembly  14  in use. A recess  76  may provide clearance for a head  78  or other portion of the fastener  70  that connects the reaction member  46  and base plate  44 . In the implementation shown, the piston actuator  48  is a rectangular bar or plate with a depending knob  72  that engages the piston  32 . The piston actuator  48  could have any suitable shape and be formed of any suitable material. 
     To lift the piston assembly  14  from the transmission case  28 , the fasteners holding the mounting flange  28  to the case  28  are removed. Thereafter, the reaction member support posts  66  are coupled to the case  28  and the ends of the base plate support posts  56  are located in the openings  52 ,  26  of the base plate  44  and mounting flange  24 , respectively (with the base plate support posts  56  extending through the piston actuator openings  74 ). The connection members  50  are then coupled to the base plate  44  and mounting flange  24  such that the hooks  58  are inserted through the openings  26  in the mounting flange  24  and their opposite ends  60  are coupled to the base plate  44 . In this way, the base plate  44  and mounting flange  24  are coupled together. The piston actuator  48  is trapped between the piston  32  and the reaction member  46  and when the connection members  50  are securely connected to the base plate  44 , the knob  72  engages and displaces the piston  32  against its return spring  42 . This moves the piston rod  20  further into the transmission  18  and thereby permits further movement of the mounting flange  24  away from the transmission case  28  with correspondingly less effective movement of the piston rod  20  relative to its clutch. 
     Next, an actuator  80  may be used to drive the base plate  44  away from the reaction member  46 . In the implementation shown, the actuator is a bolt  80  or threaded shank that is received in the threaded opening  54  of the base plate  44  and rotated until an end  81  ( FIG. 4 ) of the bolt  80  engages the reaction member  46 . Further rotation of the bolt  80  moves the base plate  44  away from the reaction member  46 , which is held against movement on the case  28  (via its support posts  66 ). As the base plate  44  moves, the hooks  58  pull the mounting flange  24  away from the case  28  and provide a clearance therebetween. A stop surface, such as a head  82  of the bolt  80  may provide a physical limit to the distance that the base plate  44  can be moved away from the reaction member  46 , and hence the mounting flange  24  can be moved away from the transmission case  28 . Otherwise, a visual indicator of the amount of base plate/mounting flange movement or other signal may be provided. In this way, movement beyond a maximum or threshold amount can reliably be avoided and in a simple manner. In at least some implementations, the mounting flange  24  may be moved off of the transmission case by between 2 mm and 40 mm or more, with one presently tested implementation being limited to 13 mm to prevent damage to the transmission. Hence, in that tested implementation, the stop surface  82  ensures a maximum movement of 13 mm of the mounting flange  24  from the transmission case  28 . Now that the piston assembly  14  has been moved off the transmission case  28 , the piston rod clamp  12  can be engaged with the piston rod  20  to facilitate removal of the piston  32  and remainder of the piston assembly  14  from the piston rod  20 . 
     The piston rod clamp  12  is shown in  FIGS. 2 ,  5 ,  9  and  10 . In at least some implementations (and as shown), the piston rod clamp  12  includes two opposed members  86 , each having a handle  88  and a clamp body  90 . The handles  88  may be elongated rigid members adapted to extend outwardly beyond the puller tool  10  to permit a user to grasp the handles  88  even when the puller tool  10  is in place on the piston assembly  14  and transmission case  28 . The clamp bodies  90  may be arranged to provide clearance with adjacent components and specifically to be received between the piston assembly mounting flange  24  and the transmission case  28 . In the implementation shown, the clamp bodies  90  have generally flat first and second surfaces  92 ,  94  adapted to be received adjacent to the mounting flange  24  and transmission case  28 , respectively. The thickness of the clamp bodies  90  is less than the maximum permitted movement of the mounting flange  24  away from the transmission case  28 . Further, the clamp bodies  90  may include a recess  96  in the first surface  92  disposed adjacent to the mounting flange  24  in assembly. The recess  96  may provide clearance for the mounting flange  24  and/or connection member hooks  58 , for example. 
     The clamp bodies  90  may each have a stepped cavity  98  defined in part by a protrusion  100  (or portion of a protrusion) extending from their second surfaces  94  so that the protrusions  100  extend from the opposite surface of the recess  96 . The cavity  98  and protrusion  100  of each clamp body  90  may be in the shape of a half-cylinder and adapted to form a generally cylindrical bore and generally cylindrical (or frustoconical) protrusion  100  when the clamp bodies  90  are positioned adjacent to each other. The cavity  98  is arranged to provide clearance for the piston rod support  40  of the piston  32  and to ensure that a clamp surface  102  of the protrusion  100  engages only the piston rod  20  and not the piston  32 . The shape of the protrusion  100  permits the clamp surface  102  of each clamp body  90  to be disposed beneath or outside of the piston rod support  40 , which may extend into a recess  104  ( FIG. 5 ) in the transmission case  28  (i.e. beneath an outer surface  106  of the case  28 ) even when the piston assembly  14  has been lifted from the case  28 . This permits the piston rod clamp  12  to engage and hold onto the piston rod  20  and not the piston  32 , and facilitate relative rotation between the piston  32  and piston rod  20 , as will be discussed further below. The cavities  98  and clamp surfaces  102  may be formed smooth and of a size to prevent deformation or damage to the piston rod  20  in use as the piston rod can remain in use with the transmission  18 . The clamp surfaces  102  may be at least 2 mm thick to improve holding the piston rod  20  and prevent providing too thin of an area of contact on the piston rod, which could otherwise damage the piston rod. When the clamp bodies  90  are fully brought together, the clamp surfaces  102  may be formed with a smooth inner radius that is the same as the piston rod  20  radius so that even higher than needed clamping forces do not unduly mar or damage the piston rod  20  and so the piston rod can remain in use with the transmission. In at least some forms, there is a small clearance or gap of 1 mm or more when the clamp bodies are brought together, and this clearance may decrease but not disappear entirely when the clamp bodies are squeezed or compressed and/or secured together. 
     To more firmly clamp the piston rod  20 , the handles  88  may be squeezed together manually. Or, as optionally shown in  FIG. 10 , the clamp bodies  90  may be held together by one or more bolts  110  or other fastener(s) to ensure a steady and consistent clamping force and/or remove the need for someone to hold onto the handles  88 . Of course, other arrangements may be employed, such as a clamp wherein the clamp bodies  90  are not separate from each other, and may be pivoted or otherwise moveable like pliers, a C-clamp, or any other suitable design. 
     In use, the piston rod clamp bodies  90  are inserted beneath the mounting flange  24  when the mounting flange  24  is raised off the transmission case  28 . The protrusion  100  is positioned within the transmission case recess  104  (or bore) and the clamp surfaces  102  are located adjacent to the piston rod  20 . Thereafter, the clamp bodies  90  are moved toward each other to clamp and hold the piston rod  20 . With the reaction bar posts  66  removed from the transmission case  28 , the puller tool  10  can be rotated to rotate the rest of the piston assembly  14  relative to the piston rod  20  (the elongated reaction bar  46  may be used for extra leverage for rotating the puller tool  10  and piston assembly  14 ). This will unscrew the piston  32  from the piston rod  20  and permit the piston assembly  14  to be completely removed from the piston rod  20 . The removed piston assembly  14  can then be taken off the puller tool  10  and a new piston assembly  14  readied for installation. 
     To install a new piston assembly  14 , the new piston assembly can be loaded into the puller tool  10  with the connection member hooks  58  and support posts  56  mated with the mounting flange  24  of the new piston assembly in the same manner as the recently removed piston assembly. The reaction bar  46  may be in place, and the actuator bolt  80  may be rotated to engage the piston actuator  48  with the piston  32  and depress or move the piston  32  against its return spring  42 . This prevents the piston assembly  14  from unduly engaging the piston rod clamp  12  as the new piston assembly is rotated onto the piston rod  20 , as discussed below. With the new piston assembly  14  loaded onto the puller tool  10 , the puller tool  10  may then be rotated relative to the piston rod  20  to screw the piston  32  of the new piston assembly  14  onto the piston rod  20 . An adhesive may be used on the mating threads to improve the connection between the piston  32  and piston rod  20 , if desired. The rotation of the puller tool  10  may be done in the same manner as the removal of the prior piston assembly, but in the opposite direction. 
     After the piston  32  is connected to the piston rod  20 , the piston rod clamp  12  may be removed and the reaction bar support posts  66  may be connected to the transmission case  28 . To lower the piston assembly  14  onto the transmission case  28 , the actuator bolt  80  may be retracted. This lowers the base plate  44  relative to the reaction bar  46  which also lowers the mounting flange  24  relative to the transmission case  28 . When the mounting flange  24  is lowered to the case  28 , the connection members  50  and the base plate support posts  56  may be removed to remove the puller tool  10  from the piston assembly  14 . Fasteners may then be inserted through the mounting flange openings  26  and tightened to connect the mounting flange  24  to the transmission case  28 . Thereafter, the dust cover  36  and any electrical and hydraulic or other fluid connections to the piston assembly  14  may be made. 
     In this way, an exteriorly accessible piston assembly  14  may be serviced or replaced without having to remove the piston rod  20  from the transmission  18 , and without having to remove the transmission  18  from the vehicle. This may be done to replace a seal, or to replace a defective piston or housing, for example. Of course, the entire piston assembly  14  may be replaced, if desired. The puller tool  10  and piston rod clamp  12  may be manually manipulated by a single person and in a relatively short period of time to simply and effectively permit repair or replacement of the piston assembly.