Abstract:
Reciprocating motion can be converted to rotary motion through a crankshaft and a connecting rod. In a connecting rod that is primarily in compression, two opposing connecting rods can be coupled to a single journal. Two bearing shell portions are placed over the journal with a pushrod placed over each bearing shell portion. The pushrods are normally in compression. To overcome the potentiality of the pushrods briefly being in tension, retainers can be coupled to the pushrods. Because both pushrods are coupled in-line, the width of the journal that can accommodate these pushrods is shorter than for a journal on which the two pushrods are side by side. The crankshaft can be shorter, stronger, and lighter weight.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application claims priority benefit from U.S. provisional patent application 61/471,236 filed 4 Apr. 2011. 
     
    
     FIELD 
       [0002]    The present disclosure relates to a pushrod connection to a journal of a rotating member. 
       BACKGROUND 
       [0003]    In  FIG. 1 , an opposed-piston, opposed-cylinder (OPOC) engine  10  is shown isometrically. An intake piston  12  and an exhaust piston  14  reciprocate within each of first and second cylinders (cylinders not shown to facilitate viewing pistons). The inner pistons  12 ′ and  14  couple to a journal (not visible) of crankshaft  20  via pushrods  16 . The outer pistons  12  and  14 ′ couple to two journals (not visible) of crankshaft  20  via pullrods  18 , with each outerpiston  12  having two pullrods  18 . The first and second cylinders in which the pistons reciprocate are parallel but offset from each other in the y direction due to the pullrods  18  associated with the cylinder shown front and leftward displaced in a negative Y direction with respect to pullrods  18  associated with the cylinder shown rear and rightward. Pushrods  16  are similarly situated with respect to each other. It is cost effective that all four pullrods  18  are identical in design and the two pushrods  16  are the same such as the design shown in  FIG. 1 . However, a disadvantage of such an offset design is that the engine is wider than it would otherwise be if the two cylinders could be arranged collinearly. Also, a torque is introduced due to the offset of the two cylinders. The combustion chamber shape  24  is shown on the tops of exhaust pistons  14  and  14 ′ and the combustion chamber shape  22  on the top of intake pistons  12  and  12 ′ is not visible in  FIG. 1 . It is desirable to minimize the number of unique parts in an assembly, but unfortunately the configuration in  FIG. 1  includes four different pistons:  12 ,  12 ′,  14 , and  14 ′. 
         [0004]    One alternative to overcome the offset cylinders is a forked rod, such as is described in U.S. Pat. No. 1,322,824, invented by F. Royce. By employing a forked rod/blade rod configuration within the engine of  FIG. 1 , the cylinders are collinear, but the length of the journal (or crank pin) is greater than the configuration in which the cranks are side by side. The goal of reducing the width of the engine by making the cylinders collinear is offset by the wider crank pin lengths. A disadvantage of such a configuration is that the piston in one cylinder couples with the crankshaft by a forked rod and the corresponding piston in the other cylinder couples with the crankshaft by a blade rod thereby increasing part count for the engine. A system for coupling the rods to the crankshaft is desired which allows common parts to be used in the two cylinders, while allowing collinear cylinders and facilitating a shorter crank pin length. 
       SUMMARY 
       [0005]    A journal and connecting rod assembly is disclosed that allows collinear cylinders while maintaining common parts. The assembly includes a cylindrical journal, a first bearing shell portion placed on the journal, and a second bearing shell portion placed on the journal and secured to the first bearing shell portion. The assembly further includes a first pushrod having a concave portion of a predetermined diameter that nests with a convex surface of the first bearing shell and a second pushrod having a concave portion of the predetermined diameter that mates with a convex surface of the second bearing shell portion. The convex surfaces of the first and second bearing shells portions are of the predetermined diameter. The assembly further includes a U-shaped first retainer coupled to the first pushrod such that the first pushrod and the first retainer encircle the journal and a U-shaped second retainer coupled to the second pushrod such that the second pushrod and the second retainer encircle the journal. 
         [0006]    The first pushrod includes a first convex shoulder and the second pushrod includes a second convex shoulder. A concave surface of the U-shaped first retainer sits on the convex shoulder; and a concave surface of the U-shaped second retainer sits on the convex shoulder. The first and second U-shaped retainers have first and second tips with a first orifice in the first tip and a second orifice in the second tip. The axes of the orifices are parallel to a central axis of the journal. 
         [0007]    First and second orifices are defined in each of the first and second pushrods with a first orifice located near a first end of the concave surface and a second orifice located near a second end of the concave surface. The orifices in the pushrods are parallel to a central axis of the journal. The assembly further includes a pin inserted through each of the first and second orifices in each of the first and second retainers wherein each pin is also inserted into the associated orifice in the associated pushrod. The pin is a substantially straight pin with a snap ring to prevent the pin from sliding longitudinally or a pin with a head at one end and threads on an end away from the head. 
         [0008]    Also disclosed in an assembly that includes a crankshaft having three cylindrical journals. The crankshaft is a single piece in contrast to a built-up crankshaft used in some forked connecting rod configurations. First and second bearing shell portions are placed on one of the journals away from an end of the crankshaft. First and second bearing shell portions are fastened together. The assembly further includes: a first pushrod placed over the first bearing shell portion, a second pushrod placed over the second bearing shell portion, a first retainer coupled to the first pushrod, and a second retainer coupled to the second pushrod. The first and second retainers are U-shaped and each pushrod forms a portion of a cylinder at an end of the pushrod proximate the journal. Each pushrod includes a shoulder. A concave portion of the U of the first retainer couples with the shoulder associated with the second pushrod. A concave portion of the U of the second retainer couples with the shoulder associated with the first pushrod. 
         [0009]    The first and second retainers have orifices defined in each tip of the U; two orifices defined in each of the pushrods, one located in each end of the cylinder; the orifices are parallel to a central axis of the journal; and one of the orifices of the retainers aligned with one of the orifices of the pushrod, the assembly further comprising: a pin inserted through each of the pairs of aligned orifices. The orifices in the pushrods are threaded, the pins are screws, and the threads of the screws engage with the threads in the associated pushrod. 
         [0010]    The assembly further includes a pilot hole in a concave surface of the first bearing shell portion, an axis of the pilot hole being approximately perpendicular with a central axis of the journal, a dowel pin placed in the pilot hole and extending outwardly from the first bearing shell portion, and an orifice in the first pushrod, the orifice being approximately perpendicular with the central axis of the journal wherein the orifice engages with the dowel pin. Relative rotational motion of the first bearing shell portion with respect to the first pushrod is substantially prevented by the pin engaging with the pilot hole in the first bearing shell portion and the orifice in the first pushrod. 
         [0011]    The assembly further includes first and second through-hole orifices defined in the first bearing shell portion near an end of the first bearing shell portion; first and second threaded orifices defined in the second bearing shell portion near an end of the second bearing shell portion; a first screw inserted through the first through-hole orifice of the first bearing shell portion and threads of the first screw engaged with the first threaded orifice of the second bearing shell portion; and a second screw inserted through the second through-hole orifice of the first bearing shell portion and threads of the second screw engaged with the second threaded orifice of the second bearing shell portion. 
         [0012]    In some embodiments, the first bearing shell portion and the second bearing shell portion have fingers extending outwardly from at least one end of each the first and second bearing shell portions, an orifice is defined in the fingers with an axis of the orifice being substantially parallel to a central axis of the journal, the fingers of the first and second bearing shell portions are enmeshed to form a box joint, and a dowel pin inserted through the orifices in the enmeshed fingers. 
         [0013]    In some embodiments, the outer surfaces of the bearing shell portions are substantially convex and sit away from the journal a predetermined amount except in the region proximate where the first and second bearing shell portions fasten together in which at least one of the bearing shell portions has an outward protrusion and the outward protrusion indexes with a gap between the first and second pushrods. 
         [0014]    In an alternative embodiment, a first through-hole orifice is defined in the first bearing shell portion near a first end of the first bearing shell portion; a second through-hole orifice is defined in the second bearing shell portion near a first end of the second bearing shell portion; a first U-shaped clip define an orifice at one tip and has a threaded portion at the other tip; and a first bolt passes through the orifice at one tip of the first clip, through the first through-hole orifice, through the second through-hole orifice, and threads into the threaded portion of the first clip. 
         [0015]    Some embodiments further include: a third through-hole orifice defined in the first bearing shell portion near a second end of the first bearing shell portion; a fourth through-hole orifice defined in the second bearing shell portion near a second end of the second bearing shell portion; a first U-shaped clip defining an orifice at one tip and having a threaded portion at the other tip; and a first bolt. The second bolt passes through the orifice at one tip of the second clip, through the third through-hole orifice, through the fourth through-hole orifice, and threads into the threaded portion of the second clip. 
         [0016]    Yet other embodiments further include: a fifth through-hole orifice defined in the first bearing shell portion near a first end of the first bearing shell portion; a sixth through-hole orifice defined in the second bearing shell portion near a first end of the second bearing shell portion; a seventh through-hole orifice defined in the first bearing shell portion near a second end of the first bearing shell portion; a eighth through-hole orifice defined in the first bearing shell portion near a second end of the first bearing shell portion; third and fourth U-shaped clips each clip defining an orifice at one tip and having a threaded portion at the other tip; and third and fourth bolts. The third bolt passes through the orifice at one tip of the third clip, through the fifth through-hole orifice, through the sixth through-hole orifice, and threads into the threaded portion of the third clip. The fourth both passes through the orifice at one tip of the fourth clip, through the seventh through-hole orifice, through the eighth through-hole orifice, and threads into the threaded portion of the fourth clip. 
         [0017]    Also disclosed is a method to assemble the connecting rods onto a journal of the crankshaft. First and second portions of a bearing shell onto the journal are placed on the journal and the two bearing shell portions are fastened together. A first pushrod is placed over the first bearing shell portion. In embodiments in which the first pushrod and the first bearing shell are pinned together, a pin is press fit into the orifice in the pushrod and the pin is engaged with a pilot hole in the bearing shell portion. Alternatively, the pin is pressed into the pilot hole in the bearing shell portion and engages with the orifice in the pushrod during assembly. A second pushrod is placed over the second bearing shell portion. Screws, or other retainer, couple tips of the first and second retainers to the first and second pushrods, respectively. 
         [0018]    One advantage of the embodiments disclosed herein is that the width of the journal associated with the two pushrods is approximately one-half the width of the situation as shown in  FIG. 1  in which pushrods  16  couple to with crankshaft  20  in a side-by-side arrangement. The crankshaft, according to embodiments in the present disclosure, may be shorter than crankshaft  20 . Or, alternatively, the radius of the journal may be reduced in diameter, which also has many benefits. In yet another alternative, the width of the journal is reduced to some extent and the diameter is also reduced. In any of these alternatives, friction in the pushrod-to-bearing connection is reduced. 
         [0019]    Various embodiments of the disclosure allow for the two cylinders to be collinear, which allows the engine to be narrower and for the torque by the offset nature of the connecting rods to be eliminated. Also, in such a configuration, the two inner pistons may be identical (either both intake or both exhausts). Similarly, the two outer pistons are identical. This reduces the number of unique parts in the engine assembly. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]      FIG. 1  illustrates an example configuration of an opposed-piston, opposed-cylinder engine in an isometric view; 
           [0021]      FIG. 2  is an exploded view of a pushrod assembly according to an embodiment of the present disclosure; 
           [0022]      FIG. 3  illustrates a cross section of the pushrod-to-crankshaft assembly of  FIG. 2  as assembled; 
           [0023]      FIG. 4  illustrates the bearing shell portions of  FIG. 2 ; 
           [0024]      FIG. 5  illustrates an alternative embodiment to secure the bearing shell portions; 
           [0025]      FIG. 6  illustrates a cross section of the pushrod-to-crankshaft assembly; 
           [0026]      FIG. 7  is an embodiment of the bearing shell portions in an exploded view; 
           [0027]      FIGS. 8 and 9  are a perspective view and a side view of the embodiment of  FIG. 7  as assembled; 
           [0028]      FIG. 10  is a pushrod according to one embodiment of the disclosure; 
           [0029]      FIG. 11  is the pushrod of  FIG. 10 , the bearing shell potions of  FIGS. 7-9 , and retainers; 
           [0030]      FIG. 12  is an embodiment of a pushrod to journal connection according to an embodiment of the present disclosure; 
           [0031]      FIG. 13  is a perspective view of the bearing shell portions of  FIG. 12 ; and 
           [0032]      FIG. 14  is a flowchart indicating a method to assemble the connecting rods with the crankshaft. 
       
    
    
     DETAILED DESCRIPTION 
       [0033]    As those of ordinary skill in the art will understand, various features of the embodiments illustrated and described with reference to any one of the Figures may be combined with features illustrated in one or more other Figures to produce alternative embodiments that are not explicitly illustrated or described. The combinations of features illustrated provide representative embodiments for typical applications. However, various combinations and modifications of the features consistent with the teachings of the present disclosure may be desired for particular applications or implementations. Those of ordinary skill in the art may recognize similar applications or implementations whether or not explicitly described or illustrated. 
         [0034]    An exploded view of a configuration a pushrod assembly  30  in which two pushrods are capable of being coupled to one journal is shown in  FIG. 2 . Bearing shell portions  32   a  and  32   b  couple together around a journal (not shown). Concave surfaces  40   a  and  40   b  of pushrods  34   a  and  34   b  nest with convex surfaces  42   a  and  42   b  of bearing shell portions  32   a  and  32   b . Pushrods  34   a  and  34   b  are held in place by retainers  36   a  and  36   b  with retainer  36   a  coupling with pushrod  34   a  via screws  38  coupling through orifices  44  of pushrod  34   a  and orifices  46  of retainer  36   a . Retainer  36   a  is horse-shoe shaped with the ends coupling with pushrod  34   a  and the circular portion nesting with a shoulder  37   b  on pushrod  34   b . Similarly, retainer  36   b  nests with a shoulder  37   a  on pushrod  34   a . The width, W, of pushrod  34   b  along the length of the pushrod is wider than the width, Y, near the tips of the concave surface  40   b . The narrower width, Y, accommodates the installation of the retainers, one of which is affixed with pushrod  34   b  and one of which engages on shoulder  37   b  of pushrod  34   b.    
         [0035]    In an alternative embodiment, both retainers  36   a  and  36   b  are screwed to one of the pushrods, e.g.,  34   b . In such embodiment, the U-shaped portions of the retainers  36   a  and  36   b  ride on the two shoulders  37   a  and  37   b  associated with the other of the pushrods  34   a . An exploded view of such an embodiment would appear nearly identical as that shown in  FIG. 2  except that retainer  36   a  is rotated with the opening of the horse-shoe shape pointing in the same direction as retainer  36   b.    
         [0036]    Each of pushrods  34   a  and  34   b , as shown in  FIG. 2 , have two shoulders  37   a  and  37   b , respectively., i.e., one facing toward the front of  FIG. 2  and one on the back side with respect to the view in  FIG. 2 . An alternative pushrod arrangement is to have only one shoulder on each of the pushrods, i.e., to cooperate with one retainer each. In such a configuration, pushrod  34   a  would have only the shoulder on the back side and pushrod  34   b  would have only the one shoulder on the front side as viewed in  FIG. 2 . Such a configuration reduces the number of machining operations. 
         [0037]    In one embodiment, an orifice  54  is formed in pushrod  34   a  that can align with a pilot hole  50  provided in bearing shell portion  32   a  when the two are nested. A pin  52  or dowel is press fit into orifice  54  and indexed with pilot hole  50 , upon assembly, to prevent relative movement of bearing shell portion  32   a  and pushrod  34   a . In such an embodiment, pushrod  34   b  moves relative to bearing shell portion  32   b . So that pushrods  34   a  and  34   b  are identical, orifice  54  can be formed in both; however, no dowel or other pin is inserted in orifice  54  associated with pushrod  34   b.    
         [0038]    Oil grooves  56  are provided on concave surfaces of bearing shell portions  32   a  and  32   b . Orifices  58  are provided through bearing shell portions  32   a  and  32   b  to provide lubrication to the convex side of the bearing shell portions  32   a  and  32   b . Oil grooves  60  are provided on the concave surfaces  40   a  and  40   b  of pushrods  34   a  and  34   b . Oil grooves  56  and  60  extend circumferentially along the surfaces, but for only a portion of the circumference. 
         [0039]    In  FIG. 3 , an assembled, inner connecting rod arrangement is shown in cross section. Bearing shell portions  32   a  and  32   b  encircle journal  70  having a central axis  72 ; journal  70  is a portion of crankshaft  20 . Concave surfaces of pushrods  34   a  and  34   b  nest with convex surfaces of bearing shell portions  32   a  and  32   b . Pushrods  34   a  and  34   b  connect on one end to pistons  112  and  114 , respectively. During operation of the engine, pushrods  34   a  and  34   b  are almost exclusively pushed toward journal  70 . However, to protect for the unusual event of the pushrods  34   a  and  34   b  being pulled, retainers  36   a  (not shown in this cross section) and  36   b  are provided and secured via screws  38 . 
         [0040]    Pushrod  34   a  is pinned to bearing shell portion  32   a  via a pin  52  inserted in pilot hole  50  in bearing shell portion  32   a  and orifice  54  in pushrod  34   a.    
         [0041]    Lubrication for the inner connecting rod assembly is provided through the crankshaft  20 . A cross section through journal  70  of crankshaft  20  shows there are two drillings forming oil passages  74  and  76 . Oil is provided to the bearing shell to journal interface and is carried to the pushrod to bearing shell interface through orifices  58  to grooves  60 . Oil is further provided to the end of the pushrods proximate the pistons through drillings  62 . 
         [0042]    An isometric drawing of bearing shell portions  32   a  and  32   b  in an exploded view is shown in  FIG. 4 . Bearing shell portions  32   a  and  32   b  are fastened by screws  72  that pass into through holes  76  which are large enough to accommodate heads of screws  72  and into threaded holes  74 . Oil grooves  56  are provided in concave surfaces  40   a  and  40   b . Oil supply to lubrication grooves  60  is provided through orifices  58 . Oil supplied to oil grooves  60  passes through oil holes  58  to the convex surfaces  80  of the bearing shell portions  32   a  and  32   b.    
         [0043]    In alternative embodiment illustrated in  FIG. 5 , bearing shell portions  81   a  and  81   b  have interlocking fingers at one end with holes  84  through fingers so that a pin  82  may be inserted through the holes. In one embodiment, bearing shell portions  81   a  and  81   b  are installed on a journal of a crankshaft with the crankshaft having material on either side of the journal so that pin  82  cannot slide out. In other embodiments without features holding the pin in place, the pin may have a head on one end and a snap ring on the other end. Alternatively, the pin may be secured by snap rings in an internal fashion. Any suitable way of securing the pin can be used. 
         [0044]      FIGS. 4 and 5  illustrate bearing shell portions that are fixed together. This ensures that the lubrication passes through the lubrication grooves, as described below. If the pushrod is always in compression then there is no need to secure the bearing shell portions to each other as forces in the system cause the bearing shell portions to remain pressed against the journal. Thus, in one embodiment, there are no screws or pins holding the two together. In assembly, the bearing shell portions can be held onto the journal by a thicker oil or grease until pushrods and retainers are installed. Even in a system with momentary instances of a loss of the pressure, it may be possible to withstand such short durations with a momentary loss of oil flow thereby also allowing the bearing shell portions to be installed without the screws or pins. 
         [0045]    In  FIG. 6 , an alternative embodiment is shown in which the bearing shell portions  132   a  and  132   b  are allowed to float. In such embodiment, bearing shell portions  132   a  and  132   b  have tabs  138  that extend outwardly. Bearing shell portions  132   a  and  132   b  cannot float completely freely as they are kept between pushrods  134   a  and  134   b . In  FIG. 6 , pushrods  134   a  and  134   b  are shown at a position at which the pushrods are the farthest away from being aligned. Above journal  70 , a large gap between pushrods  134   a  and  134   b  is open. A significant section of retainer  36   b  can be seen. Tabs  138  that are above journal  70  (in the configuration illustrated in  FIG. 6 ) are not restrained by the pushrods. However, tabs  138  that are below journal  70  are restrained by the pushrods. As crankshaft  20  rotates the upper portions of the pushrods close up until they restrain tabs  138  located above the journal. 
         [0046]    An alternative embodiment of bearing shell portions  232   a  and  232   b  is shown in  FIG. 7  in an exploded view. Bearing shell portions  232   a  and  232   b  are provided with orifices  234  and grooves  236 . Bolts  240  engage with clips  238  and are aligned with orifices  234  to secure bearing shell portions  232   a  and  232   b  together. In this embodiment, clips  238  are U shaped with one side of the U having a through hole that aligns with one of the orifices  234  of one of the bearing shell portions. The other end of clip  238  has a threaded portion with which threads of bolt  240  engage as shown in an assembled view in  FIG. 8 . An end view of the assembled bearing shell portions in  FIG. 9  show that clips  238  extend outwardly from bearing shell portions  232   a  (not visible in  FIG. 28) and 232   b.    
         [0047]    A pushrod  250  is shown in  FIG. 10 . A first end  251  couples to a piston (not shown). A concave surface  252  of pushrod  250  nests with a convex surface of one of the bearing shell portions. On either end of concave surface  252  recesses  256  are formed on either side of a protrusion  254 . Recesses  256  are provided to allow space for clips  238 , as can be seen in  FIG. 11 . In  FIG. 11 , portions of pushrods  250   a  and  250   b  are shown coupled onto bearing shell portions  232   a  and  232   b . Pushrods  250   a  and  250   b  are held together via retainers  260 . Pushrods  250   a  and  250   b  are shown in one extreme position where the U portion of the lower of the two clips  238  fits between the ends of pushrods  250   a  and  250   b , i.e., the space opened up by recesses  256 . The protrusions  254  of the two pushrods nearly touch in this position. As pushrods  250   a  and  250   b  move toward the other extreme position, bearing shell portions are allowed to float, although constrained between the recess surfaces  256 . 
         [0048]    The embodiment of the pushrod illustrated in  FIG. 10  has a protrusion  254  between recesses  256 . Alternatively, there is no such protrusion and the ends are at the height of the recesses  256 . Such an embodiment is easier to machine at the expense of a portion of the bearing surface. In applications in which bearing surface area is important the embodiment in  FIG. 10  or similar to such embodiment may be used. In other applications, the simpler shape without the protrusion may be used. 
         [0049]    The embodiment shown in  FIGS. 7-9  utilizes four clips  238 . In an alternative embodiment, two clips are provided at one end of the bearing shell portions with the other end of the bearing shell portions coupled such as is shown in  FIG. 4  or  5 . In another alternative embodiment, one clip is provided at each end of the bearing shell portions with the recesses provided accordingly. In yet another embodiment, only one clip is provided at one end of the bearing shell portions. 
         [0050]    In  FIG. 12 , a journal  300  has bearing shell portions  302   a  and  302   b  coupled thereto. Pushrods  304   a  and  304   b  nest with bearing shell portions  302   a  and  302   b . Retainers  306  are attached to pushrods  304   a  and  304   b . Bearing shell portions  302   a  and  302   b  have oil holes  308  to provide oil to the back side. Pushrods  302   a  and  302   b  have oil passages  310  that are provided oil via holes  308 . At the end of the oil passages proximate journal  300 , the passage may be greater in diameter and a hollow pin  312  is placed in oil passage  310  of one of the pushrods,  304   a  in  FIG. 12 . Pin  312  engages with pilot hole  314  in the back side of bearing shell portion  302   a . Such a pilot hole is provided also in bearing shell portion  302   b  to maintain consistent parts. A groove  316  is provided in bearing shell portion  302   a  to ensure that oil flows through pin  312  and into passage  310 . Again, such a groove  316  is provided in bearing shell portion  302   b  even though not strictly necessary. 
         [0051]    In  FIG. 13 , bearing shell portions  302   a  and  302   b  are shown assembled and in a perspective view. Groove  316  is narrower than pilot hole  314 . Pin  312 , of  FIG. 12 , remains fixed by pilot hole  314  and cannot move into groove  316 . 
         [0052]    A flowchart indicating a method to assemble the configuration of  FIG. 3  is shown in  FIG. 14 . In block  200 , pin  52  is press fit into orifice  54  of the first pushrod. In block  202  first and second bearing shell portions are placed onto the journal. In  204 , the bearing shell portions are fastened together. The first and second pushrods are placed onto first and second bearing shell portions in  206  with pin  52  engaging with pilot hole  50  in the first bearing shell portion. A rounded portion of a first of the two retainers is engaged with a shoulder on the second pushrod in  208 . Orifices in the tips of the first retainer are aligned with orifices in the first pushrod in  210 ; screws are installed in the aligned orifices. Similarly, a rounded portion of the second retainer is engaged with a shoulder of the first pushrod in  212 . In  214 , orifices in the second retainer are aligned with orifices in the second pushrod so that screws can be installed in the aligned orifices. 
         [0053]    In embodiments in which both bearing shell portions are allowed to float with respect to the pushrods, the portions of the flowchart in  FIG. 14  in which pin is press fit into the pushrod, block  200 , and the pin is engaged with the orifice in the bearing shell portion, i.e. part of block  206 , are obviated. 
         [0054]    While the best mode has been described in detail with respect to particular embodiments, those familiar with the art will recognize various alternative designs and embodiments within the scope of the following claims. While various embodiments may have been described as providing advantages or being preferred over other embodiments with respect to one or more desired characteristics, as one skilled in the art is aware, one or more characteristics may be compromised to achieve desired system attributes, which depend on the specific application and implementation. These attributes include, but are not limited to: cost, strength, durability, life cycle cost, marketability, appearance, packaging, size, serviceability, weight, manufacturability, ease of assembly, etc. The embodiments described herein that are characterized as less desirable than other embodiments or prior art implementations with respect to one or more characteristics are not outside the scope of the disclosure and may be desirable for particular applications.