Abstract:
A tool to install a retaining ring into a groove in a cylinder has a handle lever which carries an adjustable gripper constructed to engage the cylinder and a compressing lever constructed to engage a portion of the retaining ring with the compressing lever pivotally and slidably connected to the handle lever permitting relative movement between the two levers. The connection between the handle lever and the compressing lever permits them to be separated and joined together in a fashion that facilitates engaging and compressing the retaining ring for insertion into the cylinder.

Description:
FIELD OF THE INVENTION 
     This invention relates to fluid cylinders such as gas springs, accumulators and hydraulic cylinders and more particularly to an apparatus to install a retaining ring into a cylinder. 
     BACKGROUND OF THE INVENTION 
     Typically, gas springs, accumulators, and pneumatic and hydraulic cylinders utilize a round spring steel wire retaining ring to retain a seal and bearing assembly which provides a seal and bearing surface adjacent the piston or piston rod and also retains the piston or piston rod within the cylinder. The retaining ring is usually received in a radius groove machined near the open end and in the interior surface of the cylinder. The retaining ring bears on a shoulder provided by the groove and the seal and bearing housing bears on the opposite face of the retaining ring to retain the seal and bearing assembly within the cylinder. 
     During assembly of a fluid cylinder, it is necessary to install the retaining ring into the groove within the cylinder. Retaining rings are typically difficult to compress, and thus, difficult to install. Tapered sleeves and accompanying pushers received in the tapered sleeves to drive the ring through the sleeve and into the cylinder have been used to facilitate installation of retaining rings in the past, but this requires expensive turned and heat treated parts and considerable operator skill, experience and judgment to successfully and safely install the retaining rings. Also, for different sizes of cylinders and retaining rings, different sizes of tapered sleeves and pushers are required further increasing the cost of this assembly method. For small cylinders and retaining rings the pusher may be driven by striking it with a heavy mallet to drive the retaining ring into a narrower portion of the sleeve and thereby compress the ring. However, larger cylinders require use of an arbor or hydraulic press to drive the pusher for installation of the retaining ring increasing the cost, time and labor needed to install each retaining ring. 
     SUMMARY OF THE INVENTION 
     A tool to install a retaining ring into a groove in a cylinder has a handle lever which carries an adjustable gripper constructed to engage the cylinder and a compressing lever constructed to engage a portion of the retaining ring with the compressing lever pivotally and slidably connected to the handle lever permitting relative movement between the two levers. The connection between the handle lever and the compressing lever permits them to be separated and joined together in a fashion that facilitates engaging and compressing the retaining ring for insertion into the cylinder. 
     To install a retaining ring into a cylinder, a portion of the retaining ring is disposed in the cylinder with another portion of the ring extending out of the cylinder. The compressing lever is then engaged with the retaining ring and pivoted towards the handle lever. A link connected between the handle lever and compressing lever slidably advances the compressing lever as it is pivoted towards the handle lever to compress the retaining ring to a size permitting the ring to fit within the cylinder. With the retaining ring compressed, a rubber mallet or other device is used to remove the retaining ring from the tool and dispose it in the groove in the cylinder. 
     The retaining ring installation tool permits safe, easy and quick installation of the retaining ring into the cylinder and requires relatively low force and a relatively low level of skill to use. Desirably, the tool is adjustable for use with a variety of sizes of retainer rings. 
     Objects, features and advantages of this invention include providing a tool to facilitate installation of a retaining ring into a groove in a cylinder which is formed from low cost materials, requires a relatively low level of skill to operate, requires relatively little force to install retaining rings, is adjustable for use with a variety of sizes of retaining rings, eliminates the need for expensive tapered sleeves and pushers, eliminates the need for a press to drive a pusher, utilizes an over-center toggle to hold a compressed retaining ring, is compact, of relatively simple design and economical manufacture and assembly, and in service has a long and useful life. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other objects, features and advantages of this invention will be apparent from the following detailed description of the preferred embodiments and best mode, appended claims, and accompanying drawings in which: 
     FIG. 1 is a sectional view of a gas spring illustrating a retaining ring installation tool embodying the invention in a first position initially engaged with the retaining ring of the gas spring; 
     FIG. 2 is a bottom view of the retaining ring installation tool embodying the invention in a fully collapsed position; 
     FIG. 3 is a sectional view taken along line  3 — 3  of FIG. 1; 
     FIG. 4 is a partial sectional view of the gas spring of FIG. 1 illustrating the retaining ring installation tool in a second position fully engaged with and compressing the retaining ring of the gas spring; 
     FIG. 5 is a partial sectional view as in FIG. 4 illustrating the tool in a third, fully collapsed position with the retaining ring compressed and received in the cylinder; and 
     FIG. 6 is a fragmentary perspective view of the retaining ring installation tool, retaining ring and cylinder in the position of FIG.  5 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring in more detail to the drawings, FIG. 1 shows a tool  10  for installing a retaining ring  12  into a cylinder body  14  of a gas spring  16 . The tool  10  has a handle lever  18  carrying a gripper  20  that engages the cylinder body  14 , a ring compressing lever  22  slidably and pivotally carried by the handle lever  18  to engage and compress the retaining ring  12 , and a pair of links  24  connected between the levers  18 ,  22  to slidably displace the compressing lever  22  as it is pivoted relative to the handle lever  18 . The gripper  20  is adjustably carried by the handle lever  18  so that the tool  10  can accommodate a variety of retaining ring diameters. 
     As shown in FIG. 1, the gas spring  16  has a sealing and bearing assembly  26  received within the cylinder body  14  of the gas spring  16  and a piston rod  28  slidably received in the sealing and bearing assembly  26  for axial reciprocation. The cylinder  14  has an open end  30  with a circumferentially continuous sidewall  32  preferably having a first annular groove  34  in the exterior of the sidewall  32  and a base  36  preferably integrally formed with the sidewall  32  and closing one end  38  of the cylinder body  14 . The interior wall  40  of the cylinder body  14  has a second annular groove  42  formed to provide a shoulder or stop surface  44  which is engaged by the retaining ring  12  when received in the second groove  42 . The retaining ring  12  is split, may be either annular or C-shaped, and typically in cross section is round with a diameter of at least ⅛ of an inch, and made of spring steel. To admit gas into a gas chamber  46  defined by the cylinder body  14 , the piston rod  28  and the sealing and bearing assembly  26 , a filler valve  48  is threadably received within the base  36  in communication with a fill passage  50  through which gas flows into the gas chamber  46 . 
     The piston rod  28  is an elongated cylindrical member having an enlarged end portion or piston  52  preferably integrally formed with the piston rod  28  and received within the gas chamber  46 . The enlarged diameter piston  52  has a shoulder  54  which bears on the sealing and bearing assembly  26  when the piston rod  28  is at its fully extended position to retain the piston rod  28  within the cylinder body  14 . 
     The sealing and bearing assembly  26  has an annular retaining member  56  slidably received in the cylinder body  14  and having several annular grooves  58 ,  60 ,  62  formed in its interior surface. Bearing rings  64  are received in grooves  58  and  62 , and a sealing member  66  is received in groove  60 . The bearing rings  64  guide the piston rod  28  for axial reciprocation and the sealing member  66  provides a tight seal between the piston rod  28  and the retaining member  56 . An O-ring seal  68  received in an annular groove provides a gas tight seal between the retaining member  56  and the interior wall  40  of the cylinder body  14  to prevent gas from leaking out of the gas chamber  46 . To releasably retain the retaining member  56  within the cylinder body  14  the retaining member  56  has an upstream end  70  with an annular shoulder  72  constructed to engage the lower surface  74  of the retaining ring  12  which itself is engaged with the stop surface  44  formed by the second groove  42 . 
     The handle lever  18  is generally channel-shaped, as shown in FIG. 2, having a first end  76  and a second end  78 , a pair of laterally spaced apart sidewalls  80  and an upper wall  82  interconnecting the sidewalls  80  along a portion of their length. The sidewalls  80  extend beyond the upper wall  82  to the first end  76  of the handle lever  18 . The sidewalls  80  have aligned L-shaped slots  84  between the first and second ends  76 ,  78 , and aligned openings  86  between the slots  84  and the second end  78 . The L-shaped slots  84  have a longitudinal portion  85  and a transverse portion  87 . 
     For releasably and adjustably receiving the gripper  20  to accommodate a range of cylinder body and retaining ring diameters, the handle lever  18 , adjacent the first end  76 , has a plurality of notches  92  along the top surface  88  of the sidewalls  48  and a plurality of notches  94  along their bottom surfaces  90 . The notches  92  have an entrance portion  96  which facilitates adjusting the gripper  20  and a shoulder  98  which retains the gripper  20  in a desired position in use. To permit the gripper  20  to be slidably adjusted along the sidewalls  80  and the pins  100 ,  102  to be seated in different notches  94 ,  92  respectively, the notches  92  in the top surface  88  are preferably offset from the notches  94  in the bottom surface  90 . This permits the gripper  20  to be rotated or pivoted relative to a pin  100  supporting the gripper  20  in one of the notches  94  to remove a pin  102  also supporting the gripper  20  from its notch  92  by way of its entrance portion  96 . 
     A spacer pin  103  limits separation of the sidewalls  80  and retains the gripper  20  on the handle lever  18 . The pin  103  has an enlarged head  105  and shank  107  extending through aligned openings  109  in the sidewalls  80  adjacent the first end  76  of the handle lever  18 . After insertion of the spacer pin  103  through the openings  109 , an annular washer or spacer  111  is disposed on the shank  107  and a cotter pin  113  is inserted through an opening in the shank  107  to removably retain and prevent inadvertent removal of the spacer pin  103 . The handle lever  18  is preferably formed from a single piece of sheet steel which is laser-beam, high pressure water or otherwise cut or stamped and then formed into the final shape. 
     The gripper  20  has a pair of opposed sides  104 ,  105  and a hook  106  at one end facing generally in the direction of the second end  78  of the handle lever  18 . The pair of pins  100 ,  102  are press fit through the gripper and extend beyond the opposed sides  104 ,  105  to engage and seat in the notches  94 ,  92 , respectively. As discussed above, the notches  92 ,  94  are constructed and arranged to allow the gripper  20  to be easily adjusted along the sidewalls  80  without having to remove the pins  100 ,  102  from the gripper  20 . The gripper  20  locates and anchors the tool  10  to the cylinder body  14  against the reactive force the retaining ring  12  exerts on the tool  10  as the retaining ring  12  is compressed. Preferably, this is accomplished by disposing the hook  106  in the external groove  34  in the cylinder body  14 . 
     The compressing lever  22  is an elongate member received between the sidewalls  80  of the handle lever  18 . The compressing lever  22  preferably has a handle portion  108  offset from the longitudinal axis of the compressing lever  22  to more comfortably receive the fingers of the operator on the tool  10 . The compressing lever  22  has an arcuate, recessed ring-engaging surface  110  at a first end  112  and the handle portion  108  at a second end  114  with a first opening  116  and a second opening  118  between the first and second ends  112 ,  114  for attachment to the handle lever  18  and the pair of links  24 , respectively. The compressing lever  22  is slidably and pivotally attached to the handle lever  18  in the slots  84  of the handle lever  18  by a first pivot pin  120 . As shown in FIG. 2, the first pivot pin  120  has an enlarged head  122  and a shank  124  with the shank  124  extending through the slot  84  in one side wall  80  of the handle lever  18 , the first opening  116  in the compressing lever  22 , and the slot  84  in the other side wall  80  of the handle lever  18 . An annular washer or spacer  126  is then disposed on the shank  124  and a cotter pin  128  is inserted through an opening in the shank  124  to releasably retain and prevent inadvertent removal of the first pivot pin  120 . The compressing lever  22  is preferably formed from a heat-treatable alloy steel and is laser-beam, high pressure water or otherwise cut or machined and may thus be manufactured at a relatively low cost even in low volume. 
     To facilitate attachment to the compressing lever  22  and the handle lever  18 , each link  24  has a pair of openings  132  and  134 , adjacent opposed ends  136  and  138 . The opening  132  in the first end  136  of each link  24  is aligned with the second opening  118  in the compressing lever  22 , with one link  24  on each side of the compressing lever  22 . A second pivot pin  144 , which may be a standard rivet, is inserted through the aligned openings  132 ,  118  in the links  24  and the compressing lever  22 , respectively. The opening  134  in the second end  138  of each link  24  is aligned with the pair of openings  86  in the sidewalls  80  of the handle lever  18  with each link  24  adjacent a separate one of the sidewalls  80 . To connect the links  24  and handle lever  18 , a third pivot pin  150  with an enlarged head  152  at one end is inserted through one opening  86  in a side wall  80 , the openings  134  in both links  24 , and the opening  86  in the other sidewall  80 . An annular washer or spacer  156  is then disposed on the pin  150  and a cotter pin  158  is inserted through an opening in the pin  150 . The links  24  are disposed at an acute included angle relative to the handle lever  18  when the compressing lever  22  is in the first position. Desirably, the handle portion  108  of the compressing lever  22  provides clearance from the pivot pin  150  to permit the compressing lever to be fully collapsed against the handle lever  18 . Correspondingly, the handle lever  18  preferably has a relieved portion  159  aligned with the handle portion  108  of the compressing lever  22 . 
     Operation 
     To install a retaining ring  12  into a gas spring  16 , the internal components of the gas spring  16  are first assembled into the cylinder body  14 . The gripper  20  on the tool  10  is slidably adjusted on the handle lever  18  to the notches  92 ,  94  appropriate for the size of the cylinder body  14  and the retaining ring  12  to be installed therein. A portion of the retaining ring  12  is then placed into the second groove  42  inside the cylinder body  14  of the gas spring  16  with an opposite portion of the retaining ring  12  extending out of the open end  30  of the cylinder body  14 . 
     The tool  10  is then placed over the retaining ring  12  and the hook  106  of the gripper  20  is inserted into the first groove  34  in the exterior of the sidewall  32  of the cylinder body  14 . The hook  106  is positioned generally on the same side of the cylinder body  14  as the portion of the retaining ring  12  that is in the second groove  42  inside the cylinder body  14 . With the compressing lever  22  in its first position, as shown in FIG. 1, the engaging surface  110  is brought into engagement with the portion of the retaining ring  12  extending out of the cylinder body  14 . To compress the retaining ring  12 , the operator of the tool  10  manually displaces the compressing lever  22  toward the handle lever  18  causing the compressing lever  22  to pivot counter clockwise about the first pivot pin  120 , as viewed in FIG. 1, and the links  24  to pivot clockwise about the third pivot pin  150 , as viewed in FIG.  1 . Clockwise pivotal movement of the links  24  causes sliding movement of the first pivot pin  120  and the compressing lever  22  in the slots  84  toward the first end  76  of the handle lever  18 . The sliding movement is a function of the cosine of the angle ∝ (FIG. 1) spanned by the movement of the links  24 . The sliding movement of the compressing lever  22  compresses the retaining ring  12  between the engaging surface  110  and the internal wall  40  so that it may be received in the cylinder body  14 . As shown in FIG. 4, when the compressing lever  22  is in its second position, the first pivot pin  120  is fully forward in the horizontal portion  85  of the L-shaped slots  84  so that the retaining ring  12  is sufficiently compressed and may be received in the open end  30  of the cylinder body  14 . 
     As shown in FIG. 1, the engaging surface  110  of the compressing lever  22  and the third pivot pin  150  form an imaginary straight line  162 . When the compressing lever  22  is in its first position, the second pivot pin  144  is on one side  164  of the line  162 , and, as shown in FIG. 4, when the compressing lever  22  is in its second position, the second pivot pin  144  passes to the other side  166  of the line  162  providing an over-center toggle movement. Hence, the reactive force of the compressed retaining ring  12  on the compressing lever  22  tends to displace the compressing lever  22  towards the handle lever  18  to facilitate maintaining the compressing lever  22  in its second position compressing the retaining ring  12 . The compressing lever  22  tends to stay in the second position until an outside force acts on the compressing lever  22  tending to separate it from the handle lever  18 . With the compressing lever  22  tending to remain in the second position, the gripping force applied to the tool  10  by the user can be released or at least reduced as the spring force from ring  23  locks the level  22  in a closed position. 
     To disengage the compressed retaining ring  12  from the tool  10 , the tool  10  is pivoted about the hook  106  (clockwise as viewed in FIG.  5 ). Such movement forces the edge of the retaining ring  12  into the cylinder body  14 , causes the first pivot pin  120  and associated end of the compressing lever  22  to move upwardly into the vertical portion  87  of the L-shaped slots  84 , disengages the engaging surface  110  from the retaining ring  12  after it is forced into the cylinder body  14  and engages the bottom surface  90  of the sidewalls  80  with the upper surface of the retaining ring  12  and the cylinder body  14  to maintain the retaining ring  12  in the cylinder body  14  with a portion above the groove  42 . Desirably, the tool  10  can be manually operated with one hand so that the operator&#39;s other hand may be used to drive the retaining ring  12  into the groove  42  in the cylinder body  14 . This may be accomplished by striking a portion  170 , as shown in FIG. 6, of the retaining ring  12  with a hammer or mallet  172 . It may be necessary to use the mallet to remove the retaining ring  12  from the engaging surface  110 . To do this, the upper wall  82  of the tool  10  may be struck by the mallet or the ring itself may be struck by the mallet. Striking the upper wall  82  with the mallet may also seat the ring  12  in the second groove  42 . In any event, once the retaining ring  12  is fully inside the cylinder body  14 , it can be manipulated to fully seat it in the second groove  42  in the cylinder body  14 . The tool  10  is then manually removed from the gas spring  16 . With the retaining ring  12  fully seated in the second groove  42 , the gas spring  16  is fully assembled and may be filled with pressurized gas for use. 
     The increased mechanical advantage provided by the tool  10  enables quick and easy installation of various sizes of retaining rings into a cylinder body. The tool  10  may be manufactured at low cost even in small production runs and in service has a long useful life.