Patent Publication Number: US-2009239690-A1

Title: In-series two chain continuously variable transmission

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 11/032,924, filed Jan. 11, 2005, the entirety of which is hereby incorporated by reference herein. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention generally relates to endless belt power transmission systems or components. More particularly, the present invention relates to such systems or components in which there are plural belts in series that are joined via a countershaft. 
     2. Description of the Related Art 
     One type of continuously variable transmission (CVT) uses a belt/chain and pulley configuration. Such transmissions vary the input to output shaft ratio by changing the effective diameter of the pulleys. In effect, the output speed can be varied even while the input speed remains constant. Thus, the CVT allows the engine to operate in a fuel economy sweet spot even while the associated vehicle accelerates and decelerates along the freeway. 
     SUMMARY OF THE INVENTION 
     While CVT vehicles offer an upside of improved fuel economy, several perceived drawbacks have greatly limited the number of vehicles featuring such transmissions. In particular, belt/chain drives have found limited application in larger passenger vehicles and medium size trucks. These types of vehicles commonly require drive ratios that make single belt CVT technology not feasible. For instance, larger vehicles require a large high to low ratio spread in order to begin moving at one end of the ratio spread while maintaining adequate on-road speeds at the other end of the ratio spread. While large ranges can be created with large pulleys, such an approach increases the size and weight of the CVT. 
     Thus, one aspect of the present invention involves providing a continuously variable transmission in which two belts are arranged in series. By arranging the belts in series, a larger ratio spread can be employed while using smaller diameter pulleys. In addition, the input and output shafts can be coaxially positioned. 
     Another difficulty that is associated with prior continuously variable transmission designs in general is the large number of parts and the complicated assembly resulting from the large number of parts. Both the number of parts and the specialized nature of the parts drive up the manufacturing cost of the transmissions. Moreover, the complicated assembly increases required assembly man hours, which further increases the cost of the transmissions. Thus, another aspect of the present invention provides a simplified construction for the transmission by integrating components and duplicating other components. 
     A further aspect of the present invention involves a continuously variable transmission comprising a two-piece housing that defines a belt chamber. An input pulley assembly and an output pulley assembly are positioned within the belt chamber. A first transfer pulley assembly and a second transfer pulley assembly are mounted to a countershaft. A first chain extends between the input pulley assembly and the first transfer pulley assembly. A second chain extends between the second transfer pulley assembly and the output pulley assembly. The input pulley assembly comprises a first end and a second end. The first end is supported by the housing and the second end is supported by a bearing holder. The output pulley assembly comprises a first end and a second end. The first end is supported by the housing and the second end is supported by the bearing holder. The countershaft comprises a first end and a second end. The first end is supported by the housing and the second end is supported by the housing. The input pulley assembly comprises a shaft portion and a fixed disk portion. The shaft portion and the disk portion are integrally formed. The input pulley assembly also comprises a bulkhead that is axially fixed along the shaft portion and a moveable disk that is positioned between the bulkhead and the fixed disk portion. The bulkhead is secured to the shaft portion against substantial rotation relative to the shaft portion and the moveable disk portion is coupled to the bulkhead for rotation while remaining axially movable along the shaft portion relative to the bulkhead. The output pulley assembly comprises a shaft portion and a fixed disk portion. The shaft portion and the disk portion are integrally formed. The output pulley assembly also comprises a bulkhead that is axially fixed along the shaft portion and a moveable disk that is positioned between the bulkhead and the fixed disk portion. The bulkhead is secured to the shaft portion against substantial rotation relating to the shaft portion and the moveable disk portion is coupled to the bulkhead against substantial rotation while remaining axially movable along the shaft portion relative to the bulkhead. The first transfer pulley assembly comprises a fixed disk portion and a moveable disk portion. The fixed disk portion is axially and rotationally secured to the countershaft. The second transfer pulley assembly comprises a fixed disk portion and a moveable disk portion. The fixed disk portion is axially and rotationally secured to the countershaft. The moveable disk portion of the first transfer pulley assembly and the moveable disk portion of the second transfer pulley assembly are defined in a single shuttle disk member. The shuttle disk member is positioned along the countershaft between the fixed disk portion of the first transfer pulley assembly and the fixed disk portion of the second transfer pulley assembly. The shuttle disk member is adapted for axial translation along the countershaft. The shuttle disk member comprises a first bearing portion and a second bearing portion that are separated by a recessed portion. The first and second bearing portions abut the countershaft. The shuttle disc member moves back and forth along the shaft in response to the changes in the effective radii experienced by the belts and dictated by movement of the input and output shaft moveable disc portions. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
       These and other features, aspects and advantages of the present invention will now be described with reference to the drawings of a preferred embodiment, which embodiment is intended to illustrate and not to limit the invention. The drawings comprise seven figures. 
         FIG. 1  is a sectioned view of a transmission that is arranged and configured in accordance with certain features, aspects and advantages of the present invention. 
         FIG. 2  is a side view of a bearing holder employed in the transmission of  FIG. 1 . 
         FIG. 3  is a sectioned view of the bearing holder taken along the line  3 - 3  in  FIG. 2 . 
         FIG. 4  is an outside view of an assembled transmission housing used to enclose the mechanical components of the transmission of  FIG. 1 . 
         FIG. 5  is an inside view of the housing member of  FIG. 4 . 
         FIG. 6  is a sectioned view of a tube alignment fixture that can be used to mount high pressure fluid tubes in shafts for use in the transmission of  FIG. 1 . 
         FIG. 7  is an enlarged view of a portion of  FIG. 1  indicated by the circle labeled  7 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       FIG. 1  illustrates an embodiment of a transmission  10  that is arranged and configured in accordance with certain features, aspects and advantages of the present invention. While shown in the context of a dual belt transmission, some of the features, aspects and advantages can be used in single belt transmission, such as that shown in copending U.S. patent application Ser. No. 11/033,206, filed on Jan. 11, 2005, entitled SINGLE CHAIN CONTINUOUSLY VARIABLE TRANSMISSION, and having attorney docket number BROWA.037A, which is hereby incorporated by reference in its entirety. 
     The illustrated transmission  10  generally comprises an input pulley assembly  12  and an output pulley assembly  14 . A first chain  16  connects the input pulley assembly  12  to a first transfer pulley assembly  20  and a second chain  22  connects a second transfer pulley assembly  24  to the output pulley assembly  14 . The two transfer pulley assemblies  20 ,  24  are mounted on a common countershaft  26 . 
     Thus, the illustrated transmission  10  comprises a pair of chains  16 ,  22  that are mounted in series where power is transferred from an input shaft  30  to an output shaft  32  via the countershaft  26 . As used herein, the term “chain” means belt, chain or other suitable forms of endless loops that can be used to transfer power from one pulley to another pulley. “Chain” also means a series of usually metal links or rings connected to or fitted into one another and used for transmission of mechanical power. One advantage to positioning the chains  16 ,  22  in series is that the overall ratio change in the transmission  10  can be multiplied to a desirable value while maintaining relatively smaller pulley diameters and relatively smaller axial movement of the pulley when compared to a single chain transmission. While the illustrated embodiment features input and output shafts that are generally axially aligned, other configurations are possible. The axially aligned or concentric shafts, however, provide a more compact and easy to install assembly. 
     A portion of an outer housing  34  and a bearing holder  36  support the input shaft  30 . The input shaft  30  and the output shaft  32 , together with the components both supporting the respective shafts and supported by the respective shafts, are substantially identical in the illustrated arrangement. As such a description of either shaft in the illustrated embodiment can apply to the other shaft. Thus, for simplicity of description, the description of the input shaft  30  and its related components can equally apply to the output shaft  32  and its related components. Thus, reference numerals through the following description may be placed on either shaft  30 ,  32  and the components related to that shaft to simplify review of the figures and to simplify location of reference numerals. 
     The input shaft  30  comprises a first end  40  and a second end  42 . The first end  40  comprises a bore  44  that extends inward along a rotational axis  46  of the input shaft  30 . The bore  44  can have any suitable configuration. In the illustrated arrangement, the bore  44  comprises splines  50  that can be used to couple the transmission to any suitable input system. For example, an output shaft from the engine can be coupled to the transmission by the splines  50 . Other suitable coupling structures can be used. 
     Externally, the first end  40  of the input shaft  30  comprises a threaded region  52 , a journal region  54  and a spline region  56 . The threaded region  52  preferably is positioned somewhat inboard of the extreme end of the first end  40 . In other words, between the extreme end and the threaded region  52 , a smooth region preferably is provided against which a seal  60  abuts. A lock nut  62  engages the threaded region  52 . The illustrated lock nut  62  secures an inner race  64  of a bearing  66  while a retaining ring  72  secures an outer race  70  of the bearing  66  in position. Any suitable arrangement can be used to secure the retaining ring  72  in position. In the illustrated arrangement, bolts  74  secure the ring in position. Thus, in the illustrated arrangement, the retaining ring  72  and the nut  62  capture the bearing  66  in position along the journal region  54  of the input shaft  30  such that the bearing  66  can resist thrust loads in both directions. 
     A bulkhead  80  comprises internal splines that engage the spline region  56  of the input shaft  30 . The bulkhead  80  can be formed by casting, forging or any other suitable technique. In some arrangements, such as the illustrated arrangement, the bulkhead  80  and the input shaft  30  can comprise a locating step  82 , which acts to properly position the bulkhead  80  relative to the input shaft  30  during assembly. The spline coupling of the bulkhead  80  to the input shaft  30  rotationally secures the bulkhead  80  and the input shaft  30  with minimal backlash. Thus, the input shaft  30  transfers input torque to the bulkhead  80  through the spline connection. 
     The illustrated bulkhead  80  also comprises an outer skirt  84 . An outer surface of the skirt  84  preferably comprises a spline region  86  and a bearing region  90 . In the illustrated arrangement, a small gap is provided between the spline region  86  and the bearing region  90 . Moreover, the outer surface of the skirt  84  also comprises a ring groove  92 . The ring groove  92  accommodates an o-ring that is positioned to seal or substantially seal a sliding connection between the skirt  84  and a cylinder wall  94 . The cylinder wall  94  slides along the skirt  84  during operation of the pulley assembly  12 , as will be described in greater detail below. 
     With continued reference to  FIG. 1 , the second end  42  of the input shaft  30  comprises a disk portion  100  and a journal portion  102 . At its extreme second end, the illustrated input shaft  30  comprises a stepped bore  104 . The stepped bore  104  preferably has a larger diameter portion that extends inward through the disk portion  100  of the illustrated shaft  30 . A smaller diameter portion then extends a short distance beyond the disk portion  100  toward the first end  40  of the shaft  30 . 
     Adjacent to the extreme second end, the journal portion  102  defines an inner race of a bearing  110 . As such, the journal portion preferably replaces an inner race of the bearing  110  and reduces the number of components that must be assembled when building the transmission  10 . In some embodiments, however, the bearing  110  can include an inner race that is secured to or positioned on the shaft  30  in any suitable manner. 
     Adjacent to the journal portion  102  of the illustrated shaft  30 , the disk portion  100  extends outward from the main body of the shaft  30 . The illustrated disk portion  100  is integrally formed with the shaft  30  in the illustrated arrangement. In the illustrated arrangement, the shaft  30  can be made from a simple forging. In other configurations, the disk portion  100  can be separately formed and secured to the shaft  30  in any suitable manner. The disk portion  100  forms one side of the cone shaped opening in which the chain  16  is positioned. 
     The cylinder wall  94  described above forms a portion of a moveable disk  112  that translates along a portion of the input shaft  30 . The cylinder wall  94  preferably is integrally formed with the main portion of the moveable disk. As such, the moveable disk  112  preferably is formed as a near net size forging. In other arrangements, the cylinder wall  94  can be formed separately and secured to the moveable disk  112  in any suitable manner. The illustrated arrangement, however, advantageously reduces manufacturing and assembly costs. 
     In the illustrated embodiment, the main portion of the moveable disk  112  is interposed between the disk portion  100  of the input shaft  30  and the bulkhead  80 . The moveable disk  112  advantageously comprises a slight step  114  where the cylinder wall  94  joins the main body of the disk. The step  114  allows the cylinder wall  94  to have an enlarged diameter while the main body of the disk is less likely to interfere with rotation of the first transfer pulley assembly  20 . 
     The cylinder wall  94  also comprises a spline region  116 . The spline region  116  engages the spline region  86  formed on the skirt  84  of the bulkhead  80 . Because the cylinder wall  94  moves axially relative to the bulkhead  80 , the spline region  116  of the cylinder wall can be substantially shorter in length than the spline region  86  of the skirt  84  of the bulkhead  80 . In some arrangements, the spline region  86  of the skirt  84  can be shorter in length than the spline region  116  of the cylinder wall  94 . 
     A cylinder chamber  118  is defined within a region generally bounded by the bulkhead  80 , the cylinder wall  94  and the disk portion of the moveable disk  112 . This cylinder chamber  118  comprises a pressure chamber into which fluid can be introduced and from which fluid can be evacuated to cause movement of the moveable disk  112  relative to the bulkhead  80 . As discussed above, the sliding connection between the skirt  84  and the cylinder wall  94  is sealed by an o-ring or any other suitable sealing component. 
     The inside diameter of the cylinder wall  94  forms a close tolerance large bearing surface with the bearing region  90  of the bulkhead skirt  84 . In addition, a bore defined through an axial center of the moveable disk  112  is sized to form another close tolerance bearing surface relative to the input shaft  30 . With reference to  FIG. 7 , the bore comprises a very slight step such that the portion of the bore positioned closest to the disk portion  100  of the input shaft  30  forms the bearing surface while the portion disposed closer to the bulkhead  80  has a slightly larger diameter. Thus, the interface between the input shaft  30  and the smaller diameter portion of the bore through the moveable disk  112  forms a first bearing and the interface between the inner surface of the cylinder wall and the outer surface of the skirt  84  of the bulkhead  80  forms a second bearing. 
     The two bearings are spaced with the larger diameter portion being positioned away from the chain  16 . Together, the two bearings define an ample length to diameter ratio such that the face of the moveable disk  112  that bears against the chain  16  can remain substantially square and concentric without substantial binding or overloading during movement. In most embodiments, this arrangement facilitates movement of the moveable disk  112  even though the disk  112  is subjected to large asymmetric loads by the interface with the chain  16 . 
     Hydraulic pressure changes within the chamber  118  during ratio changes causes the disk  112  to move relative to the bulkhead  80 . The movement causes relative movement at the spline regions  86 ,  116 . Because the large diameter bearing is positioned generally adjacent the spline regions  86 ,  116  in the illustrated arrangement, a tendency for the moveable disk  112  to wobble relative to the axis  46  during combined axial movement and rotational movement is greatly reduced or eliminated. Thus, the large diameter bearing surface forms a dominant alignment feature in the illustrated arrangement. 
     As described above, the second end  42  of the shaft  30  defines the inner race of the bearing  110  that supports that end of the shaft. Preferably, the bearing  110  is positioned within the bearing holder  36 .  FIGS. 2 and 3  illustrate one configuration of the bearing holder  36 . The bearing holder  36  preferably is designed to be secured generally centrally within the housing  34 . In the illustrated arrangement, threaded fasteners  120  secure the bearing holder  36  in position relative to the housing  34 . In particular, the housing comprises a first portion  122  and a second portion  124  with the bearing holder  36  interposed between the first portion  122  and the second portion  124 . The housing portions have been designed for manufacture with a single aluminum permanent mold but other manufacturing techniques, and corresponding design changes, can be used. For instance, given high enough production quantities, aluminum die casting can be used and the design can incorporate differing wall thicknesses and support ribs. 
     As illustrated in  FIG. 2 , the bearing holder  36  comprises internally threaded apertures  126  positioned about its peripheral surface. As illustrated in  FIG. 3 , the apertures  126  preferably are arranged in pairs with one of each pair of apertures  126  being used to secure the bearing holder  36  to the respective portion  122 ,  124  of the housing  36 . The bearing holder  36  also can be formed by die casting aluminum. 
     With reference to  FIGS. 1 and 3 , the bearing holder  36  comprises a pair of generally annular grooves  130 . The grooves  130  preferably define a bearing mounting location. In the illustrated arrangement, an outer race  132  of each bearing  110  can be pressed into place within the respective groove  130 . As such, the bearing holder  36  is positioned between the second ends of the input shaft  30  and the output shaft  32  in the illustrated arrangement. Thus, the bearing holder  36  advantageously can support both the input shaft  30  and the output shaft  32 . The bearings  110  advantageously can contain what can be termed a full complement of rollers for maximum radial load carrying capability. The bearings  110  also preferably require no cage. Instead, the rollers can be held in place during assembly with high-viscosity grease. Moreover, as discussed above, the shafts  30 ,  32  define the inner race for the bearings  110  and no separate inner race is required. In some embodiments, other types and constructions of bearings, with or without inner races, can be used. 
     With reference now to  FIGS. 1-3 , the bearing holder  36  also comprises a pair of entry passages  134  for a fluid source. Preferably, the passages  134  are entry passages for a high pressure fluid system that is used to feed oil, lubricant or other suitable fluids to the chambers  118  and that is used to supply oil, lubricant or other suitable fluids for lubrication of many of the moving components of the transmission  10 . The passages  134  preferably comprise an enlarged opening that can comprise internal threads such that tubing (not shown) can be connected to the passages  134  with suitable fittings. The tubing can be used to deliver the high pressure fluid from any suitable source. 
     The passages  134  extend to axial passages  136  that extend toward the shafts  30 ,  32 . The axial passages  136  preferably also comprise an enlarged opening that can comprise internal threads. The enlarged opening can accommodate a threaded compression fitting  140 . Other suitable configurations also can be used. 
     With reference to  FIG. 1 , a tube  142  can be secured to the bearing holder  36  by the compression fitting  140 . The tube  142  advantageously defines a backbone of a supply gallery  144 . The tube  142  preferably is axially positioned in the respective shaft  30 ,  32 . Thus, the tube  142  preferably is positioned along the axial centerline of the respective shaft  30 ,  32 . 
     It is noted that during assembly of the transmission  10 , the tubes  142  preferably are secured to the bearing holder  36  prior to being inserted into the shafts. The compression fittings  140  are used to grasp the outside diameters of the tubes  142  and secure them to the bearing holder  36 . This mounting arrangement results in the tubes  142  being restrained against any substantial axial or rotational movement relative to the bearing holder. Any other suitable technique can be used to secure the tubes  142  against rotation and axial movement. For instance, a pin can be used to secure the tubes  142  in position in the bearing holder  36 . Such an arrangement is shown and described in copending U.S. patent application Ser. No. 11/033,206, filed on Jan. 11, 2005, entitled SINGLE CHAIN CONTINUOUSLY VARIABLE TRANSMISSION, and having attorney docket number BROWA.037A, which is hereby incorporated by reference in its entirety. 
     Any desired centering adjustments to the tubes can be made once they have been secured to the bearing holder  36  by bending the tubes and a fixture can be designed to verify that the tubes  142  have been inserted generally coaxially within the shafts. Such a fixture will be described below. In any event, as illustrated, the tubes  142  are somewhat cantilevered between the shaft bore ends  42  and the bearing holder  36  such that some flexing of the tubes  142  is permitted to accommodate small misalignments. 
     During operation of the transmission  10 , the tubes  142  may drag against portions of the bore in which they are inserted and the tubes  142  therefore are expected to wear to some degree over time. Thus, the clearance between the tubes  142  and the bore in which they are inserted is expected to be on the order of between about 0.001 and 0.002 inches in the illustrated arrangement. Given the relatively close tolerance, the interaction between the tube  142  and the bore create a structure that can function similar to a labyrinth seal that allows a low leakage rate without the need for sealing rings or other sealing structures. Such structures as a labyrinth seal can be used and/or the tolerances can be altered if desired to manipulate the leakage rate. 
     A distal end  146  of the tube  142  carries a plug  150 . The plug closes off the distal end of the tube  142  and the tube  142  is not secured to the respective shaft  30 ,  32 . Thus, the tube carries the thrust loading created by the high pressure fluid supply system. As such, no, or very minimal, thrust load is transferred to the shafts from the high pressure fluid supply system in the illustrated arrangement. 
     Fluid is transmitted from the tube  142  to the chamber  118  via cross holes  152  that are positioned within a region of the respective shaft  30 ,  32  that contains a radial fluid passage  154 . The fluid pressure variations that are fed into the chambers  118  via the tubes  142  are used to maintain chain clamping forces and to actuate the moveable disks  112 . The radial fluid passage  154  preferably extends between the bore that contains the tube  142  and an outer diameter of the respective shaft  30 ,  32 . The radial fluid passage  154  is axially positioned in a location that generally corresponds to the chamber  118 . In the illustrated arrangement, the dimension of the passage  154  in the axial direction of the shaft  30 ,  32 , which preferably is the diameter of the passage  154 , is generally defined by the stroke limits of the moveable disk  112 . In the illustrated arrangement, a slot  156  provides a fluid connection between the chamber  118  and the passage  154  when the moveable pulley assembly  112  is in its position closest to the bulkhead  80  because illustrated moveable disk  112  otherwise closes off the passage. In the illustrated arrangement, as best shown in  FIG. 7 , a stop  157  can be positioned between the bulkhead  80  and the moveable disk  112 . The stop  157  can be configured as a washer or a similar annular member and preferably spaces the moveable disk  112  from the bulkhead  80  to maintain the cylinder chamber  118  with at least a minimum volume. The slot  156  preferably intersects a chamfered edge  160  of the disk  112  such that the fluid communication can be maintained regardless of the angular orientation of the shaft  30 ,  32 . 
     With continued reference to  FIG. 1 , a small amount of fluid leakage travels down the bore along the tube  142  to lubricate the interface between the bore and the tube  142 . Of this small amount of leakage, some portion exits the shaft  30 ,  32  via a small radial passage  162 . The fluid passing through the passage  162  lubricates the bearing  66 . Another portion of the leakage flows in the opposite direction to lubricate the bearing holder  36  and the associated roller bearings. 
     The housing  34  supports the illustrated countershaft  26  at each end. As shown in  FIG. 1 , the countershaft supports both of the first and second transfer pulleys  20 ,  24 . Each of these pulleys  20 ,  24  comprises a fixed disk  170 . The fixed disks  170  form half of the pulleys  20 ,  24 . The other half of the pulleys  20 ,  24  is defined by a shuttle disk  172 . The shuttle disk  172  is adapted to move axially along the countershaft  26  between the two fixed disks  170 . 
     As shown in  FIG. 1 , the countershaft  26  has a first end  174  and a second end  176 . Each end contains a large bore  180  and the two large bores  180  are connected by a gallery bore  182 . 
     The countershaft  26  also comprises an exterior threaded region  184  at each end  174 ,  176 . A locknut  186  engages the threaded region. Each locknut  186  axially secures the respective fixed disk  170  in position on the countershaft  26 . Moreover, a plurality of spring pins  190  or other suitable components secure the fixed disk  170  in rotational position on the countershaft  26  such that the connections between the fixed disks  170  and the countershaft  26  form substantially zero backlash connections. In the illustrated arrangement, the pins  190  extend into a shoulder formed on the countershaft  26 . Other suitable arrangements can be used to mount the fixed disks  170  to the countershaft  26 . 
     The fixed disks  170  can be formed by forging or any other suitable technique. The fixed disks  170  preferably comprise a journal portion  192  and a disk portion  194 . The journal portion  192  defines an inner race for a bearing  196 . The bearing  196  can be secured in a recess formed in the outer housing  34 . Other arrangements, including using a bearing with an inner race that is mounted on the fixed disk  170 , also can be used. The disk portion  194  can comprise an outer contour that enables compact packaging of the transmission  10 . For instance, the outer contour of each disk portion  194  can have a recessed portion that accommodates a portion of the moveable disk  112  of the input and output shafts  30 ,  32  respectively. 
     The illustrated shuttle disk  172  comprises a pair of disk portions  200  and can be manufactured by forging or any other suitable technique. The disk portions  200  are connected by a sleeve portion  202 . In some configurations, a key  204  or other suitable construction can be used to rotationally secure the shuttle disk  172  to the countershaft  26 . In other configurations, the shuttle disk  172  is not rotationally secured to the countershaft  26 . The shuttle disk  172  advantageously is capable of sliding movement along an axial direction of the countershaft  26 . As the shuttle disk  172  moves between the fixed disks  170 , the effective diameter of the transfer pulleys  20 ,  24  vary. Preferably, the shuttle disk  172  floats on the countershaft  26  as a bearing. More preferably, a slightly larger diameter bore is positioned between two smaller diameter bores such that the smaller diameter bores define bearing surfaces relative to the countershaft  26  and the slightly larger diameter bore defines a cavity and reduces the surface contact between the shuttle disk  172  and the countershaft  26 . 
     Similar to the fluid supply system described above, a tube  210  extends into the gallery bore  184 . In the illustrated arrangement, a pair of tubes  210  is provided and the tubes extend only partway into the gallery bore  184 . The outer ends of the tubes  210  are secured with threaded compression fittings  211  into supply ports  213 . Between the inner ends of the tubes  210 , three radial passages  212 ,  214 ,  216  are provided. The radial passages  212 ,  214 ,  216  extend from the gallery bore  184  to the outer diameter of the countershaft  26 . Two of the passages  212 ,  214  define chain lubrication and cooling ports while the third passage  216  supplies fluid to the interface between the shuttle disk  172  and the countershaft  26 . Other fluid supply arrangements can be used but the illustrated arrangement is advantageously simple and generally provides an axially balanced thrust loading. 
     During operation, a portion of the fluid supplied to the countershaft  26  passes out of the gallery bore  182  in the space defined between the tubes  210  and the bore  182 . The portion that passes from the gallery bore  182  in this manner leaks to supply fluid to the bearings  196  and/or passes to the inside surfaces of the housing. Moreover, fluid from the assemblies relating to the input and output shafts  30 ,  32  leaks downward within the housing. This leakage collects within a groove  220  formed in each portion  122 ,  124  of the housing and drops through a passage  222  formed in each portion  122 ,  124  of the housing. This leakage then lubricates the bearings  196  of the countershaft  26 . As illustrated, a lower portion of the housing contains a baffle plate  224  that defines, in part, a collection chamber  226 , reservoir or the like. Pick-up passages  230  extend into the collection chamber  226 . The pick-up passages  230  can be used to draw used fluid from within the transmission  10  to a reservoir (not shown) or the like such that the fluid can be filtered and returned to the transmission through the appropriate pressure feed conduits. 
     With reference to  FIGS. 1 ,  4  and  5 , the housing portions  122 ,  124  preferably are substantially identical to each other. In the illustrated arrangement, the difference between the two housings consists in a groove  300  that accommodates an o-ring or suitable sealing member. The groove  300  can be manufactured in one side after identical castings are used to manufacture both portions  122 ,  124 . Moreover, the housing portions  122 ,  124  provide multiple possible port locations and such locations can be used in only one or in both portions  122 ,  124 . In the illustrated construction, two of the port locations in one portion are used for high pressure supply ports  302 . These ports  302  are connected with hoses to the ports that are connected to the passages  134  formed in the bearing holder  36 . A pick-up port  304  also extends through at least one of the housing portions  122 ,  124 . Moreover, a series of bosses  310  allow the use of threaded fasteners  312  to secure the two housing portions  122 ,  124  together to enclose the working mechanisms of the transmission  10 . 
     As discussed above, tubing is inserted into bores formed in the input shaft  30 , the countershaft  26  and the output shaft  32 . The tubes have a close fit within the bores and thus an alignment fixture  400  has been designed to help properly position the tubes within the bores to reduce the likelihood of extreme wear caused by contact between the bore and the tube. With reference now to  FIG. 6 , a fixture  400  is shown therein. The fixture  400  comprises a short collar  402  and a bushing  404 . The collar  402  has a through hole  406 . In the illustrated arrangement, the hole  406  has a conical portion and a cylindrical portion. The bushing  404  is sized for a close sliding fit within at least the cylindrical portion of the hole  406 . 
     The collar  402  is inserted along the inside diameter of the bearing outer race, which will have been embedded into the bearing holder  36 . By insertion of the collar  402 , the fixture will be generally concentric to the bearing holder axis and the fixture will be generally square relative to the bearing holder&#39;s face. The tube  142  will then protrude through the hole  406 . The bushing  404  is then threaded over the tube  142  and slid toward the collar  402 . If the bushing  404  slides into the hole  406 , then the tube  142  is properly aligned. If the bushing  404  does not slide into the hole  406 , then the tube  142  is not properly aligned and the tubing can be bent to achieve a proper alignment. 
     Although the present invention has been described in terms of a certain embodiment, other embodiments apparent to those of ordinary skill in the art also are within the scope of this invention. Thus, various changes and modifications may be made without departing from the spirit and scope of the invention. For instance, various components may be repositioned as desired. Moreover, not all of the features, aspects and advantages are necessarily required to practice the present invention. Accordingly, the scope of the present invention is intended to be defined only by the claims that follow.