Patent Publication Number: US-2005143213-A1

Title: Differential transaxle assembly

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
      This application claims the benefit of U.S. Provisional Patent Application No. 60/533,087, entitled “Differential Transaxle Assembly”, filed Dec. 29, 2003, which is incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION  
      The present invention relates generally to differential transaxle assemblies and, more particularly, to a differential transaxle assembly having a tube separate therefrom for attachment to a long shaft end of the differential transaxle assembly.  
      In conventional differential transaxle assembly designs, the long shaft end of the transaxle is either firmly supported in bearings at a mounting sleeve supported by a cast structure integral with a gear case of the transaxle, or the long shaft is left exposed to the elements with a separate casting at the end of the long shaft supporting the shaft bearing. A problem with the first alternative is that changes in mounting lengths are somewhat expensive to effect, and machining of the housing can be complicated. A problem with the second alternative is that leaving the shaft exposed to the elements not only increases the possibility of corrosion of the shaft but also increases the possibility of physical injury. An additional problem with the second alternative is that, by having no structural connection between the gear case and the bearing support, no reaction torque can be transferred to and carried by the bearing support.  
      It would therefore be desirable to have a differential transaxle assembly that overcomes these problems. Specifically, it would be desirable to have a differential transaxle assembly that can be manufactured for a cost that is reduced from that of the conventional designs. Additionally, it would be desirable to have a differential transaxle assembly with mounting distances that can be easily changed to accommodate a variety of chassis. Lastly, it would be desirable to provide for the tight enclosure of both rotating axle shafts to reduce the possibilities of corrosion and physical injury.  
     BRIEF SUMMARY OF THE INVENTION  
      Briefly stated, the present invention is a differential transaxle assembly for use with any one of a plurality of different chassis. Each chassis has a pair of mounting locations spaced apart a predetermined distance. Each of the different chassis has a different distance between the mounting locations. The differential transaxle assembly comprises a gear case having a predetermined configuration with a pair of opposed apertures therein. Each of the apertures is aligned along a longitudinal axis of the gear case. The gear case has a gear case length measured along the longitudinal axis between the apertures. The gear case length is less than the distances between the mounting location of the different chassis. A first output shaft is rotatably positioned in one of the apertures and is at least substantially aligned with the longitudinal axis of the gear case. The first output shaft has a first outboard end disposed outside of the gear case. A second output shaft is rotatably positioned in the other of the apertures and is at least substantially aligned with the longitudinal axis of the gear case. The second output shaft has a second outboard end disposed outside of the gear case. First and second supports connect the differential transaxle assembly to the mounting locations of the chassis. The first support is located proximate the first outboard end of the first output shaft. The second support is located proximate the second outboard end of the second output shaft. A tube separate from the gear case has a first end and an oppositely disposed second end and defines a tube length measured between the first and second ends. The first end of the tube is secured to one of the first and second supports. The second end of the tube is secured to the gear case. The tube surrounds at least one of the first and second output shafts. The tube length is such to enable the first and second supports to be appropriately spaced to correspond to the mounting locations of the particular chassis with which the differential transaxle assembly is being used.  
      In another aspect, the present invention is a differential transaxle assembly for use with any one of a plurality of different chassis. Each chassis has a pair of mounting locations spaced apart a predetermined distance. Each of the different chassis has a different distance between the mounting locations. The differential transaxle assembly comprises a gear case having a predetermined configuration with a pair of opposed apertures therein. Each of the apertures is aligned along a longitudinal axis of the gear case. The gear case has a gear case length measured along the longitudinal axis between the apertures. The gear case length is less than the distances between the mounting locations of the different chassis. A first output shaft is rotatably positioned in one of the apertures and is at least substantially aligned with the longitudinal axis of the gear case. The first output shaft has a first outboard end disposed outside of the gear case. A second output shaft is rotatably positioned in the other of the apertures and is at least substantially aligned with the longitudinal axis of the gear case. The second output shaft has a second outboard end disposed outside of the gear case. First and second supports connect the differential transaxle assembly to the mounting locations of the chassis. The first support is located proximate the first outboard end of the first output shaft, and the second support is located proximate the second outboard end of the second output shaft. A tube separate from the gear case has a first end and an oppositely disposed second end and defines a tube length measured between the first and second ends. The first end of the tube is integrally molded with one of the first and second supports, and the second end of the tube is secured to the gear case. The tube surrounds at least one of the first and second output shafts. The tube length is such to enable the first and second supports to be appropriately spaced to correspond to the mounting locations of the particular chassis with which the differential transaxle assembly is being used.  
      In another aspect, the present invention is a method for assembling a differential transaxle assembly for use with a chassis having a pair of mounting locations spaced apart a predetermined distance. The method comprises the steps of forming a gear case having a cavity and a pair of opposed apertures in communication with the cavity, such that each of the apertures are aligned along a longitudinal axis of the gear case. The gear case has a predetermined length measured between the apertures. The gear case length is less than the distance between the mounting locations of the chassis. A first output shaft is positioned in one of the apertures, such that the first output shaft is at least substantially aligned with the longitudinal axis of the gear case. The first output shaft has a first inboard end within the cavity and a first outboard end disposed outside of the gear case. A second output shaft is positioned in the other of the apertures, such that the second output shaft is at least substantially aligned with the longitudinal axis of the gear case. The second output shaft has a second inboard end within the cavity and a second outboard end disposed outside of the gear case. A gear assembly is positioned within the cavity in operative engagement with the first and second inboard ends of the first and second output shafts for transferring torque to the first and second output shafts. A tube is formed having a first end and an oppositely disposed second end defining a tube length measured therebetween. The second end of the tube is secured to one of the apertures of the gear case so that the tube is at least substantially aligned with the longitudinal axis of the gear case, with one of the first and second output shafts disposed within the tube. A first support is located at the first end of the tube. A second support is located proximate the other of the apertures of the gear case. The tube length is determined according to the distance between the mounting locations of the chassis so that the first and second supports correspond and align with the mounting locations of the chassis. 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS  
      The foregoing summary, as well as the following detailed description of preferred embodiments of the invention, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there is shown in the drawings embodiments which are presently preferred. It should be understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown.  
      In the drawings:  
       FIG. 1  is a bottom rear partially exploded perspective view of a differential transaxle assembly in accordance with a first preferred embodiment of the present invention shown in relation to a chassis with which the differential transaxle assembly can be used;  
       FIG. 2  is a rear elevational view of the differential transaxle assembly of  FIG. 1 ;  
       FIG. 3  is a right-side elevational view of the differential transaxle assembly of  FIG. 1 ;  
       FIG. 4  is an enlarged cross-sectional view of the differential transaxle assembly of  FIG. 1 , taken along the line  4 - 4  of  FIG. 3 ;  
       FIG. 5  is a rear elevational view of a differential transaxle assembly in accordance with a second preferred embodiment of the present invention;  
       FIG. 6  is a right-side elevational view of the differential transaxle assembly of  FIG. 5 ;  
       FIG. 7  is an enlarged cross-sectional view of the differential transaxle assembly of  FIG. 5 , taken along the line  7 - 7  of  FIG. 6 ; and  
       FIG. 8  is an exploded perspective view of the differential transaxle assembly of  FIG. 5 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
      Certain terminology is used in the following description for convenience only and is not limiting. The words “right,”. “left,” “upper,” and “lower” designate directions in the drawings to which reference is made. The terminology includes the words above specifically mentioned, derivatives thereof, and words of similar import.  
      Referring to the drawings in details, wherein like numerals indicate like elements throughout, there is shown in  FIGS. 1-4  a differential transaxle assembly, indicated generally at  10 , in accordance with a first preferred embodiment of the present invention.  
      Referring to  FIG. 1 , the differential transaxle assembly  10  is intended for use with any one of a plurality of different chassis, the plurality of different chassis being associated with various powered vehicles and machines. Although  FIG. 1  and the description below describe the use of the differential transaxle assembly  10  with a chassis  92  of an electric scooter  90  for use by elderly and/or otherwise at least slightly incapacitated people, it is within the spirit and scope of the present invention that the differential transaxle assembly  10  be used with chassis of other types of machines, automobiles and vehicles, such as, but not limited to, golf carts, floor cleaning machines and shopping cart pulling machines. Also, although described in the context of electrically-powered devices, it is within the spirit and scope of the present invention that the differential transaxle assembly  10  be used with vehicles and machines powered by alternate means, such as gasoline or natural gas motors, for instance.  
      The chassis  92  has a pair of mounting locations  94  spaced apart a predetermined distance W. The distance W between the mounting locations  94  varies according to the vehicle or machine with which it is being used. Even with respect to the scooter  90 , depending on the size and type of the scooter  90 , the distance W between the mounting locations  94  of the chassis  92  will vary. As will be described below, a mounting length L of the differential transaxle assembly  10  can be relatively easily altered in order to attach the differential transaxle assembly  10  to the mounting locations  94  of the chassis  92 , regardless of the distance W therebetween. That is, the differential transaxle assembly  10  can be readily sized to fit different size vehicles. Once attached to the chassis  92 , the differential transaxle assembly  10  functions to power wheels  96  rotatably attached thereto in order to drive the scooter  90  along a surface.  
      Referring to  FIGS. 2-4 , the differential transaxle assembly  10  includes a housing or gear case  20  having a predetermined configuration with a pair of opposed apertures  20   a ,  20   b  therein. Preferably, the gear case  20  is die cast aluminum, although it is within the spirit and scope of the present invention that the gear case  20  be made from a different material, provided it is still capable of functioning as described below. Each of the apertures  20   a ,  20   b  is preferably aligned along a longitudinal axis X of the gear case  20 . The gear case  20  has a gear case length G measured along the longitudinal axis X between the apertures  20   a ,  20   b . Preferably, the gear case length G is less than the distance W between the mounting locations  94  of the chassis  92 .  
      It is preferable that the gear case length G be a standard length so that multiple differently-sized molds for the gear case  20  are unnecessary, thereby reducing costs associated with the manufacture of the differential transaxle assembly  10 . In this way, the length G and shape of the gear case  20  remains generally constant, regardless of the mounting length L of the differential transaxle assembly  10 .  
      Preferably, the gear case  20  is a generally closed structure defining a cavity  21  therein. The apertures  20   a ,  20   b  are in communication with the cavity  21  to form openings between the cavity  21  and the outside. The gear case  20  preferably has a removable cover  20   c  to allow access to the cavity  21  within the gear case  20 .  
      A first output shaft  22  is rotatably positioned in one of the apertures  20   a  of the gear case  20 . The first output shaft  22  is at least substantially aligned with the longitudinal axis X of the gear case  20 . The first output shaft  22  has a first outboard end  22   a  disposed outside of the gear case  20  and a first inboard end  22   b  disposed within the cavity  21 . A second output shaft  24  is rotatably positioned in the other of the apertures  20   b  of the gear case  20  and is at least substantially aligned with the longitudinal axis X of the gear case  20 . The second output shaft  24  has a second outboard end  24   a  disposed outside of the gear case  20  and a second inboard end  24   b  disposed within the cavity  21 . It is preferable that the first output shaft  22  is longer than the second output shaft  24 , although it is within the spirit and scope of the present invention that the first output shaft  22  is shorter than the second output shaft  24  or that the first and second output shafts  22 ,  24  are the same size. Preferably, the first and second output shafts  22 ,  24  are made of steel alloy, although it is within the spirit and scope of the present invention that another material be used, provided the alternate material is capable of functioning as described below.  
      Conventional bearings  30  are preferably disposed around the first and second output shafts  22 ,  24 , within the apertures  20   a ,  20   b  between the gear case  20  and the first and second output shafts  22 ,  24 , in order to allow the first and second output shafts  22 ,  24  to rotate with respect to the gear case  20 . Preferably, the first and second output shafts  22 ,  24  include splines  22   c ,  24   c  proximate the outboard ends  22   a ,  24   a  thereof in order to rotationally fix the wheels  96  of the scooter  90  thereto once the differential transaxle assembly  10  is mounted to the chassis  92 .  
      An electric motor  12  or other propulsion device is preferably fixed to the outside of the gear case  20  and is oriented so that an output shaft  13  of the motor  12  is directed toward an opening  20   d  in the gear case  20 . The motor  12  is preferably powered by a conventional rechargeable battery.  
      Referring to  FIG. 4 , a drive pinion  16  is affixed to an end of the output shaft  13  via a motor coupling  14 . Preferably, the drive pinion  16  is disposed substantially within the cavity  21  of the gear case  20 . The drive pinion  16  preferably engages with and drives a differential gear assembly  50  within the cavity  21  of the gear case  20 . The gear assembly  50  is preferably in operative engagement with the first and second inboard ends  22   b ,  24   b  of the first and second output shafts  22 ,  24  for transferring torque to the first and second output shafts  22 ,  24 . The gear assembly  50  generally includes a drive gear  52 , which is driven by the drive pinion  16 , and four differential bevel gears  54  for operatively engaging the drive gear  52  to the first and second output shafts  22 ,  24 . In this way, torque generated by the motor  12  is transferred to the first and second output shafts  22 ,  24  in order to ultimately drive the wheels  96  of the scooter  90 . Additional details and description of the gear assembly  50  and other features of the gear case  20  are set forth in U.S. Pat. No. 6,626,788 B2, which is incorporated by reference herein.  
      Referring again to  FIGS. 2-4 , first and second supports  26 ,  28  are used for connecting the differential transaxle assembly  10  to the mounting locations  94  of the chassis  92 . Preferably, the first support  26  is located proximate the first outboard end  22   a  of the first output shaft  22 , and the second support  28  is located proximate the second outboard end  24   a  of the second output shaft  24 . The first and second supports  26 ,  28  are preferably die cast aluminum with a generally rectangular outer surface (see  FIG. 3 ) and a generally circular hole therethrough for accommodating one of the first and second output shafts  22 ,  24  therein. Preferably, conventional bearings  30  are disposed between the first and second output shafts  22 ,  24  and their respective first and second supports  26 ,  28  to allow the first and second output shafts  22 ,  24  to rotate with respect to the first and second supports  26 ,  28 . A rubber sleeve  32  is preferably disposed around the outer, generally rectangular surfaces of the first and second supports  26 ,  28 . The second support  28  is preferably integrally molded with the gear case  20  so that the hole through the second support  28  corresponds with the second aperture  20   b  of the gear case. Although this is preferred, it is within the spirit and scope of the present invention that the second support  28  be formed separately from the gear case  20 .  
      The differential transaxle assembly  10  further includes a tube  40  formed separately from the gear case  20 . The tube  40  has a first end  40   a  and a second end  40   b  oppositely disposed from the first end  40   a . The tube  40  has a tube length T measured between the first and second ends  40   a ,  40   b . The first end  40   a  of the tube  40  is secured to one of the first and second supports  26 ,  28 , and the second end  40   b  of the tube  40  is secured to the gear case  20 . The tube  40  surrounds at least one of the first and second output shafts  22 ,  24 . The tube  40  is preferably die cast aluminum, although it is within the spirit and scope of the present invention that the tube  40  be formed from a different material using a different process provided the tube  40  is still capable of functioning as described herein.  
      Preferably, the tube  40  is disposed between the first support  26  and the gear case  20  to substantially cover the first output shaft  22 . Although this is preferred, it is within the spirit and scope of the present invention that the tube  40  be used to cover the second output shaft  24  or that separate tubes  40  be used to cover both the first and second output shafts  22 ,  24 . Preferably, the tube  40  has a substantially circular cross-section with the first and second ends  40   a ,  40   b  of the tube  40  having diameters that are sufficiently small to fit within at least the first aperture  20   a  of the gear case  20  and the hole through the first support  26  to enable the insertion of the first and second ends  40   a ,  40   b  of the tube  40  therein. It is preferred that a wall thickness of the tube  40  is decreased proximate the first and second ends  40   a ,  40   b  in order to allow the tube  40  to fit within the holes of the first support  26  and the first  20   a  of the gear case  20 . Although this is preferred, it is within the spirit and scope of the present invention that the tube  40  has a uniform wall thickness along the entire tube length T and a uniform diameter of the tube  40  that is sufficiently sized to fit within the first aperture  20   a  and the hole of the first support  26 .  
      Referring to  FIGS. 1-4 , preferably, the first and second ends  40   a ,  40   b  of the tube  40  are secured within the first aperture  20   a  of the gear case  20  and the hole of the first support  26 , respectively, using press fitting and/or locking fluids. The tube  40  is additionally secured within the differential transaxle assembly  10  due to the mounting of the differential transaxle assembly  10  to the chassis  92 . That is, once the first and second supports  26 ,  28  are attached to the mounting locations  94  of the chassis  92 , the first and second supports  26 ,  28  are basically fixed with respect to the differential transaxle assembly  10 , restraining the components of the differential transaxle assembly  10  from moving along the longitudinal axis X and essentially trapping the tube  40  between the first support  26  and the gear case  20 .  
      The tube length T is determined to enable the first and second supports  26 ,  28  of the assembled differential transaxle assembly  10  to be appropriately spaced to correspond to the mounting locations  94  of the particular chassis  92  with which the differential transaxle assembly  10  is being used. That is, the mounting length L of the differential transaxle assembly  10 , measured between the first and second supports  26 ,  28 , is essentially equal to the gear case length G plus the tube length T. In order to properly mount the differential transaxle assembly  10  to the chassis  92 , the mounting length L of the differential transaxle assembly  10  must correspond to the distance W between the mounting locations  94  of the chassis  92  so that the first and second supports  26 ,  28  align with the mounting locations  94 .  
      As stated above, the gear case length G is generally standard. Although the gear case length G could be changed by using a different mold, doing so would increase the manufacturing cost and time of the gear case  20 , which, in most instances, would not be practical from a business standpoint. However, the tube length T of the tube  40  can be relatively easily and inexpensively formed to an appropriate size using various methods, including, but not limited to, machining at least one of the first and second ends  40   a ,  40   b  of the tube  40  to size. In this way, the length L of the differential transaxle assembly  10  can be varied to correspond with the distance W between the mounting locations  94  of the chassis  92  by varying the tube length T of the tube  40 . This allows the first and second supports  26 ,  28  of the differential transaxle assembly  10  to correspond and align with the mounting locations  94  of the chassis  92  so that the differential transaxle assembly  10  can be mounted to the chassis  92 .  
      It is preferred that the mounting locations  94  each have a top and a bottom surface defining a space therebetween. It is within these spaces that the first and second supports  26 ,  28  of the differential transaxle assembly  10  are inserted. The bottom surfaces of the mounting locations  94  are then bolted or otherwise affixed to the top surfaces in order to compress the first and second supports  26 ,  28  therebetween and retain the differential transaxle assembly  10  on the chassis  92 . Although this method of mounting is preferred, it is within the spirit and scope of the present invention that the differential transaxle assembly  10  be mounted in other ways, such as, for instance, bolting or otherwise affixing the first and second supports  26 ,  28  directly to the chassis  92 .  
      When the differential transaxle assembly  10  is fully assembled, the second support  28  is preferably integrally molded with the gear case  20  and the tube  40  is secured between the gear case  20  and the first support  26 , as stated above. In this way, the differential transaxle assembly  10  forms a relatively rigid structure between the first and second supports  26 ,  28 . During operation of the differential transaxle assembly  10 , a torque is produced. When mounted to the chassis  92 , this torque translates to a reaction torque experienced at the first and second supports  26 ,  28  and the corresponding mounting locations  94 . Because the differential transaxle assembly  10  forms a relatively rigid structure, the reaction torque is substantially equally distributed between the first and second supports  26 ,  28 . This situation is more favorable than having only one of the first and second supports  26 ,  28  experience the majority of the reaction torque, which would be the case if no tube  40  or other structure were rigidly connected between the gear case  20  and the first or second support  26 ,  28 .  
      By substantially covering one of the first and second output shafts  22 ,  24 , the tube  40  is able to help protect the first or second output shaft  22 ,  24  from water and/or dirt to decrease the possibility of corrosion of the first or second output shaft  22 ,  24 . Additionally, by at least partially shielding at least one of the first and second output shafts  22 ,  24  from being contacted, the tube  40  acts to help protect people and animals in the vicinity of the differential transaxle assembly  10  from being injured by at least one of the first and second output shafts  22 ,  24 , which can rotate at relatively high speeds during operation of the differential transaxle assembly  10 .  
      Referring to  FIGS. 5-8 , there is shown a differential transaxle assembly  110  of a second preferred embodiment which is generally similar to the differential transaxle assembly  10  of the first preferred embodiment with the main differences being in the shape and configuration of a tube  140 . As such, only the differences between the first and second preferred embodiments will be discussed.  
      Referring to  FIGS. 5 and 8 , the tube  140  has a side wall having a rounded portion  140   c  and a flat portion  140   d , rather than having a circular cross-section like the tube  40  of the first preferred embodiment. It is intended that the flat portion  140   d  of the tube  140  abuts or is otherwise proximate a corresponding flat surface  112   a  of a motor  112 , which is located proximate the tube  140  when the differential transaxle assembly  110  is assembled. The flat portion  140   d  of the tube  140  provides additional clearance so that a larger motor  112  can be used with the differential transaxle assembly  110  than would otherwise be able to be used if the tube  140  had a different shape, such as being circular in cross-section, for instance.  
      The tube  140  further includes at least one indentation  142  in the side wall thereof proximate a second end  140   b . The at least one indentation  142  is sufficiently sized and shaped for interaction with at least one corresponding protrusion  120   e  of a gear case  120 . When the second end  140   b  of the tube  140  is inserted within an aperture  120   a  of the gear case  120 , the at least one protrusion  120   e  is disposed within the at least one indentation  142  of the tube  140  to restrain the tube  140  from rotating with respect to the gear case  120  during operation of the differential transaxle assembly  110 . Preferably, there are two diametrically opposed indentations  142  in the tube  140  and two corresponding protrusions  120   e  of the gear case  120 . Although this is preferred, it is within the spirit and scope of the present invention that there be more or less than two indentations  142  and corresponding protrusions  120   e.    
      Lastly, the tube  140  of the second preferred embodiment has a first support  126  at a first end  140   a  of the tube  140 . However, rather than being secured thereto using a press fitting and/or locking fluids like in the first preferred embodiment, the first support  126  of the second preferred embodiment is integrally molded or formed with the tube  140 . In this way, a rigid connection is formed between the tube and the first support  126  to ensure that the two components do not become separated during operation of the differential transaxle assembly  110 , short of a catastrophic failure of the tube  140 .  
      The remaining structure and operation of the differential transaxle assembly  110  is essentially similar to that described above with respect to the differential transaxle assembly  10  of the first preferred embodiment.  
      In another aspect, the present invention is a method for assembling the differential transaxle assembly  10 ,  110  for use with the chassis  92  having a pair of mounting locations  94  spaced apart a predetermined distance W. Initially, the gear case  20 ,  120  is formed having a cavity  21 ,  121  and opposed apertures  20   a ,  20   b ,  120   a ,  120   b  aligned along a longitudinal axis X of the gear case  20 . The apertures  20   a ,  20   b ,  120   a ,  120   b  are in communication with the cavity  21 ,  121 . The gear case  20 ,  120  has a predetermined length G measured between the apertures  20   a ,  20   b ,  120   a ,  120   b . The gear case length G is less than the distance W between the mounting locations  94  of the chassis  92 .  
      Next, the first output shaft  22  is positioned in one of the apertures  20   a ,  20   b ,  120   a ,  120   b , such that the first output shaft  22  is at least substantially aligned with the longitudinal axis X of the gear case  20 ,  120 . The first output shaft is positioned so that the first inboard end  22   b  is located within the cavity  21 ,  121  and the first outboard end  22   a  is disposed outside of the gear case  20 ,  120 .  
      The second output shaft  24  is then positioned in the other of the apertures  20   b ,  20   a ,  120   b ,  120   a , such that the second output shaft  24  is at least substantially aligned with the longitudinal axis X of the gear case  20 ,  120 . The second output shaft  24  is positioned within the aperture  20   b ,  20   a ,  120   b ,  120   a , such that the second inboard end  24   b  is disposed within the cavity  21 ,  121  and the second outboard end  24   a  is disposed outside of the gear case  20 ,  120 .  
      The gear assembly  50  is now positioned within the cavity  21 ,  121  in operative engagement with the first and second inboard ends  22   b ,  24   b  of the first and second output shafts  22 ,  24  for transferring torque to the first and second output shafts  22 ,  24 .  
      The tube  40 ,  140  is then formed or selected with a particular tube length T, as measured between the first end  40   a ,  140   a  and the oppositely disposed second end  40   b ,  140   b . The second end  40   b ,  140   b  of the tube  40 ,  140  is secured to one of the apertures  20   a ,  20   b ,  120   a ,  120   b  of the gear case  20 ,  120  so that the tube  40 ,  140  is at least substantially aligned with the longitudinal axis X of the gear case  20 ,  120 , with one of the first and second output shafts  22 ,  24  disposed within the tube  40 ,  140 . The first support  26 ,  126  is located at the first end  40   a ,  140   a  of the tube  40 ,  140 . The second support  28 ,  128  is then located proximate the other of the apertures  20   b ,  20   a ,  120   b ,  120   a  of the gear case  20 ,  120 .  
      During manufacture and assembly of the differential transaxle assembly  10 ,  110 , the tube length T is determined according to the distance W between the mounting locations  94  of the chassis  92  so that the first and second supports  26 ,  28 ,  126 ,  128  correspond and align with the mounting locations  94  of the chassis  92 . In this way, the differential transaxle assembly  10 ,  110  can be used with chassis of different vehicles or machines, which have different distances between the mounting locations of the respective vehicles or machines.  
      When assembling the differential transaxle assembly  10  of the first preferred embodiment, the first end  40   a  of the tube  40  is secured to the first support  26 , and the second end  40   b  of the tube  40  is secured to the gear case  20  using a press fitting and/or locking fluids. When assembling the differential transaxle assembly  110  of the second preferred embodiment, the first support  126  is integrally molded with the first end  140   a  of the tube  140 , and the second end  140   b  of the tube  140  is secured to the gear case  120  using press fitting and/or locking fluids.  
      The differential transaxle assembly  10 ,  110  described above improves upon the prior art in that it can be manufactured for a cost that is reduced from that of the conventional designs. By separately forming the tube  40 ,  140  from the gear case  20 ,  120 , less complicated molds and molding techniques can be used, thereby resulting in a reduced manufacturing cost. Additionally, because the length L of the differential transaxle assembly  10 ,  110  can be relatively easily changed by changing the tube length T of the tube  40 ,  140 , the differential transaxle assembly  10 ,  110  is capable of being mounted on a variety of different chassis. Moreover, because only the tube length T need be altered to change the mounting length L of the differential transaxle assembly  10 ,  110 , the gear case  20 ,  120  can be manufactured with a standard gear case length G to eliminate the need for differently-shaped molds for the gear case  20 ,  120 , thereby further reducing the manufacturing cost. Lastly, because the tube  40 ,  140  substantially completely encloses at least one of the first and second output shafts  22 ,  24 , the tube  40 ,  140  protects at least one of the first and second output shafts  22 ,  24  from dirt and/or water to reduce the possibility of corrosion of at least one of the first and second output shafts  22 ,  24 . Moreover, because the tube  40 ,  140  shields at least one of the first and second output shafts  22 ,  24 , the likelihood of physical injury from contacting at least one of the rotating first and second output shafts  22 ,  24  is drastically reduced from that of an uncovered rotating shaft.  
      It will be appreciated by those skilled in the art that changes could be made to the embodiments described above without departing from the broad inventive concepts thereof. It is understood, therefore, that this invention is not limited to the particular embodiments disclosed, but it is intended to cover modifications within the spirit and scope of the present invention as defined by the appended claims.