Abstract:
A vehicle drive system includes a housing, a sun gear, a planet gear carrier, and planetary gears supported by the planet gear carrier and engaged with the sun gear. An output gear includes a ring gear engaged with the plurality of planetary gears, connected to and forming a part of a differential having a rotatable differential case. An interlock is configured to affix the planetary gear carrier to the housing in a first position, and to affix the sun gear to the planet gear carrier in a second position, the axles rotating in a first direction in a first position, and a second direction in a second position. An actuating system moves the planet gear carrier between the first and second positions. A kit includes the transmission and adapts a two wheeled motorcycle to a three wheeled motorcycle.

Description:
FIELD OF THE INVENTION 
       [0001]    The invention relates to a differential for a three wheeled motor vehicle, and particularly a final drive or gear system for adapting a two wheeled motorcycle to a three wheeled motorcycle, including a reverse gear set. 
       BACKGROUND OF THE INVENTION 
       [0002]    Commercially retailed motorcycles are commonly sold with a forward-only operating transmission. Providing a reverse gear is often deemed unnecessary, because many motorcycles are small enough that a rider can physically push the motorcycle in reverse, using the rider&#39;s legs while sitting for example. Some motorcycles are very large, however, and it is difficult, particularly for a smaller rider, to physically push the vehicle in reverse. Should a motorcycle be converted into a tricycle, or “trike”, having an extended rear axle for supporting two wheels instead of just one, it becomes further unfeasible for a rider to physically push the vehicle in reverse. 
         [0003]    Methods for converting motorcycles to tricycles are known, and kits providing for the conversion are commercially available. At least in part because converting a motorcycle to a tricycle will substantially increase the weight and bulk of the vehicle, a conversion may further modify the motorcycle with a means to reverse the vehicle. 
         [0004]    The art described in this section is not intended to constitute an admission that any patent, publication or other information referred to herein is “prior art” with respect to this invention, unless specifically designated as such. In addition, this section should not be construed to mean that a search has been made or that no other pertinent information as defined in 37 CFR §1.56(a) exists. 
       SUMMARY OF THE INVENTION 
       [0005]    The disclosure provides for a vehicle final drive system and a kit for converting a two wheeled motorcycle to a three wheeled motorcycle, as described herein. 
         [0006]    In accordance with an embodiment of the disclosure, a vehicle transmission or drive system comprises a housing; a sun gear driven by a motor of the vehicle; —a planet gear carrier; —a plurality of planetary gears rotatably mounted to the planet gear carrier and engaged with the sun gear; —an output gear including a ring gear engaged with the plurality of planetary gears, a rotatable differential case connected to the ring gear, one or more spider gears rotatable in connection with the differential case, and two side gears each connected to an axle; and an interlock configured to affix the planet gear carrier to the housing in a first position, whereby the axles rotate in a first direction when the sun gear is rotated in a first direction, the interlock further configured to affix the sun gear to the planet gear carrier in a second position, whereby the axles rotate in a second direction when the sun gear is rotated in a first direction. 
         [0007]    In embodiments thereof, the sun gear is a shaft extending into the housing and, in some embodiments, may further comprise a first end plate and a second end plate affixed to the housing, the axle extending through an aperture in the first end plate, the shaft extending through an aperture in the second end plate. 
         [0008]    Additional embodiments include, a housing cover attachable to the housing, the attached housing cover enveloping the planet gear carrier and the output gear. 
         [0009]    It should be understood that, in some embodiments, the planet gear carrier is configured to move between a first position and a second position in a direction substantially parallel to the axle. The disclosure thus serves to switch axle rotation between a first direction and a second direction where, in some embodiments, the first direction of axle rotation is associated with the vehicle moving in reverse, and the second direction of axle rotation is associated with the vehicle moving forward. 
         [0010]    In a yet further embodiment, the final drive system includes a first set of dogs provided on a first end of the planet gear carrier to be coupled with the output gear in a first position, and a second set of dogs provided on a second end of the planet gear carrier to affix the planet gear carrier to the housing in a second position. Other embodiments include a first set of teeth provided on a first end of the planet gear carrier to be coupled to mating teeth of the output gear in a first position, and a second set of teeth provided on a second end of the planet gear carrier to affix the planet gear carrier to mating teeth of the housing in a second position. 
         [0011]    In another embodiment of the disclosure, a vehicle final drive system comprises a housing; a sun gear driven by a motor of the vehicle, the sun gear including an internal bore; a planet gear carrier; a plurality of planetary gears rotatably mounted to the planet gear carrier and engaged with the sun gear; an output gear including a ring gear engaged with the plurality of planetary gears, a rotatable differential case connected to the ring gear, one or more spider gears rotatable in connection with the differential case, and two side gears each connected to an axle; an actuating system for moving the planet gear carrier between a first position and a second position, the actuating system including at least one actuator member connected to the planet gear carrier, and an actuator and a biasing element associated with each at least one actuator, the actuator configured to exert an actuating force against the actuator member, the biasing element configured to exert a resisting force against the actuator member in a direction substantially opposing the actuating force; and—an interlock configured to affix the planet gear carrier to the housing in the first position, whereby the axles rotate in a first direction when the sun gear is rotated in a first direction, the interlock further configured to affix the sun gear to the planet gear carrier in the second position, whereby the axles rotate in a second direction when the sun gear is rotated in a first direction. 
         [0012]    In an embodiments where an actuating system is provided, the actuating system may include, in some embodiments, an inner plate, the at least one actuator member connected to the inner plate, the inner plate affixed to the planet gear carrier and movable between the first and second positions. In additional embodiments, the at least one actuator member is an actuator pin extending through an aperture in the inner plate, and the associated actuator and biasing element are provided proximate to opposing sides of the inner plate. In further embodiments, the vehicle final drive system includes at least one thrust bearing provided proximate to the inner plate and the planet gear carrier configured to rotatably bear the planet gear carrier against the actuating force and the resisting force. 
         [0013]    The disclosure also provides for a kit for converting a two wheeled motorcycle to a three wheeled motorcycle, the kit comprising: a housing mountable to a swing arm of the motorcycle; a sun gear supported within the housing and driven by a motor of the vehicle; a planet gear carrier; a plurality of planetary gears rotatably mounted to the planet gear carrier and engaged with the sun gear; an output gear including a rotatable differential case having a ring gear engaged with the plurality of planetary gears at a first end, and one or more spider gears rotatably mounted at a second, opposite end, and two side gears matingly engaged with the one or more spider gears, each side gear connected to a rear axle; an actuating system for moving the planet gear carrier between a first position and a second position, the actuating system including at least one actuator member connected to the planet gear carrier, and an actuator and a biasing element associated with each at least one actuator, the actuator configured to exert an actuating force against the actuator member, the biasing element configured to exert a resisting force against the actuator member in a direction substantially opposing the actuating force; and an interlock configured to affix the planet gear carrier to the housing in the first position, whereby the axles rotate in a first direction when the sun gear is rotated in a first direction, the interlock further configured to affix the sun gear to the planet gear carrier in the second position, whereby the axles rotate in a second direction when the sun gear is rotated in a first direction. 
         [0014]    In some embodiments, the kit further comprises user control means for activating and deactivating the actuator of the actuating system. In additional embodiments, the actuating system includes an inner plate, the at least one actuator member connected to the inner plate, the inner plate affixed to the planet gear carrier and movable between the first and second positions. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    A more complete understanding of the present invention, and the attendant advantages and features thereof, will be more readily understood by reference to the following detailed description when considered in conjunction with the accompanying drawings wherein: 
           [0016]      FIG. 1  depicts a top view of a swing arm and final drive as presently known in the art; 
           [0017]      FIG. 2  depicts a top view of a reversible gear system in accordance with the disclosure engaged with the swing arm and final drive as shown in  FIG. 1 ; 
           [0018]      FIG. 3  depicts a top view of the reversible gear system as shown in  FIG. 2  installed to a support frame; 
           [0019]      FIG. 4  depicts an exploded view of the internal plates of the housing of the reversible gear system as shown in  FIG. 2 ; 
           [0020]      FIG. 5  depicts an exploded view of the internal components of the housing of the reversible gear system as shown in  FIG. 2 ; 
           [0021]      FIG. 6  depicts a front view of the installed reversible gear system as shown in  FIG. 3  with the bottom of the housing removed to illustrate the internal features; 
           [0022]      FIG. 7A  depicts a schematic view of a final drive of the disclosure, including a first gear set and a second gear set in a first position, for forward rotation of wheel axles; 
           [0023]      FIG. 7B  depicts the schematic view of  FIG. 7A , the second gear set in a second position, for reverse rotation of the wheel axles; 
           [0024]      FIG. 8  depicts a cross-section of the installed reversible gear system as shown in  FIG. 3  from a bottom view; 
           [0025]      FIG. 9  depicts the gears of the reversible gear system rotating in a forward direction while in first position; and 
           [0026]      FIG. 10  depicts the gears of the reversible gear system rotating in reverse direction while in a second position. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0027]    In the description which follows, any reference to direction or orientation is intended primarily and solely for purposes of illustration and is not intended in any way as a limitation to the scope of the present invention. Also, the particular embodiments described herein are not to be considered as limiting of the present invention. 
         [0028]      FIG. 1  depicts the rear portion of a shaft driven motorcycle, as may be found in the prior art. A swing arm  110 , also referred to as a swing fork or a pivot fork, extends towards the rear of the vehicle and is coupled to a final drive  120 .  FIG. 1  illustrates a two sided swing arm, however a single sided swing arm is contemplated as modifiable within the disclosure. Conversion of a two sided swing arm  110  is advantageously resistant to the additional torquing forces attributed to a conversion from a single wheel axis  114  to a double wheel axis  114 A, such as when converting the vehicle from a motorcycle to a motorized tricycle. Contained in the final drive  120  is a final drive gear (not shown) connected to a drive shaft (not shown), typically within the swing arm. Attachment points  122  for the suspension, as well as a pin  124  for attaching suspension elements, are additionally shown, as commonly found in commercially sold motorcycles. Coupled to the final drive  120  is a rear wheel axle  114 , which supports rotation of a wheel mounted to the axle. 
         [0029]    In reference now to  FIGS. 2 and 3 , a drive assembly  100  includes a reversing gear housing  200 , in accordance with the disclosure, is mounted to the rear of the vehicle. A housing cover  230  is provided for enveloping, protecting, and/or at least partially containing the contents of housing  200 . An O-ring  282  is provided proximate to each end of cover  230  in order to seal cover  230  to housing  200 . Cover  230  may further include a sealable opening, such as a hinged window, to provide access to the components within housing  200  without requiring removal of the cover, thereby facilitating more cost and time efficient maintenance, including for example lubrication. As shown, the dimensions of a back cover  254  of first gear set  250  can be adjusted in accordance to the dimensions of swing arm  110  being used, particularly the width of the swing arm. Housing  200  may be advantageously positioned in connection with frame  210 , on the rear of the vehicle, in order to facilitate access to the inside of housing  200 , for ease of replacing parts, and for other maintenance, including adjustment. As will be evident from the disclosure, while contents, gears, and gear sets within housing  200  rotate with respect to a wheel axis extending along wheel axle  114 / 114 A, housing  200  is rotationally fixed with respect to rotation about the wheel axis by securing means disclosed herein, such as fastening to frame  210 . 
         [0030]    In one embodiment, the support frame  210  is attached to housing  200  by ⅜″ grade eight bolts, although other bolts and fasteners may be utilized in accordance with the disclosure. A permanent attachment, such as by welding or spot welding housing  200  to frame  210 , is also contemplated within the disclosure. In one embodiment frame  210  is advantageously constructed from chromoly steel and end plates  210  are constructed from cold rolled steel, however other materials of sufficient strength, durability, and performance are contemplated within the disclosure. 
         [0031]    The dimensions of cover  230  may be advantageously adjustable, either before or after manufacturing, to accommodate the dimensional specifications of the original components of the vehicle. For example, different models of motorcycles have different dimensions for their swing arms  110 . By advantageously bolting, or removably fastening by other means known or to be developed, cover  230  to housing  200 , the housing  200  may be modified to conform for use in a variety of vehicles with a variety of dimensions. Although any known method of fastening may be used for securing housing  200  and cover  230 , it is advantageous for housing  200  to attach to final drive  120  using the same bolts provided from the factory production of the drive shaft model vehicle. As will be evident throughout the disclosure, the ease of use and installation of housing  200 , as well as the simplicity of several elements in the various embodiments of the disclosure, advantageously reduce installation and maintenance time, as well as reduce installation and maintenance costs. 
         [0032]    In order to aide alignment of housing  200 , a two-piece clamp  204  advantageously secures cover  230  with swing arm  110 . Clamp  204  secures and aligns housing  200  along wheel axle  114 A and with respect to final drive  120 . Although clamp  204  is illustrated on the opposite side of final drive  120 , it is contemplated within the disclosure to provide clamp  204  on the final drive side in some embodiments, or to provide a plurality of clamps  204  on each one or both sides of housing  200  in alternative embodiments. An oil seal  202  may be further provided on one or both sides of swing arm  110  where axle  114  exits from housing  200 . 
         [0033]    In accordance with the disclosure, drive assembly  100  advantageously includes support for a variety of safety features that may be provided with commercially sold motorcycles and other motor vehicles contemplated within the disclosure. On some vehicles, for example, a pin  124  is provided on each side of swing arm  110  for supporting a brake caliper (not shown), thereby restricting rotation when the brakes are applied. Although the dimensions of pin  124  vary from model to model, a 14 mm threaded pin is a common dimensional example. Pins  124 , for example, may be advantageously used to help maintain alignment of housing  200 , as best illustrated in  FIG. 2 . 
         [0034]    The original suspension system of the vehicle may also be advantageously utilized, although it is contemplated that a variety of suspension systems may be utilized with drive assembly  100  in accordance with the disclosure. As illustrated, a double sided swing arm  110  is utilized which provides significantly greater twisting torque support than a single sided swing arm, although both embodiments are contemplated within the disclosure. 
         [0035]    Referring now to  FIGS. 4-10 , a reverse drive assembly  100  includes a reversing differential housing  200  having a rotatable differential case or first gear set  250  that is positioned proximate a planet gear carrier or second rotatable gear set  260 , and a motor driven shaft  280  rotatably driven by final drive  120 . Throughout the disclosure, differential case  250  may also be referred to as a first or output gear set  250 , and planet gear carrier  260  may also be referred to as the second or input gear set  260 . Shaft  280 , as depicted in the illustrated embodiment, includes a spiral cut gear configured for meshing with planetary gears  262  as described herein, on a first end, and having a pinion, for engaging a final drive gear, thereby transmitting power as described herein, on a second end. Shaft  280  further includes an internal bore for accommodating the wheel axle  114 / 114 A. A set of differential gears  252 , including spider gears and a side gear connected to each wheel axle  114 / 114 A connected to the differential case  250 , are provided in first gear set  250  and function, in an embodiment of the disclosure, as a differential for wheel axles  114 / 114 A. In some embodiments, such as a two wheel hub  130  embodiment, wheel axle  114 / 114 A may be divided into a first part and a second part, each part connected to a respective wheel hub  130 . In this embodiment, a first part of axle  114 A may extend through a first end plate  232 , while a second part of axle  114 A extends through an internal bore of shaft  280 . A variety of differential mechanisms, known or to be developed, are contemplated to be used in place of or together with spider gear  252 , in accordance with the disclosure, including, but not limited to, limited slip, locking, automatic torque biasing, sliding pin, sliding cam, spool, epicyclic, and spur-gear differentials, as well as electronically aided differentials, such as those found in anti-lock braking systems. 
         [0036]    At least one planetary gear  262  is housed in planet gear carrier  260 , each planetary gear  262  advantageously including spiral cut gears for quietness and reliability. In the embodiment illustrated, there are six (6) equally spaced planetary gears, provided in a casing of the second gear set  260 , although other numbers of gears may be used. Each planetary gear  262  is externally splined or grooved to cooperate or mesh with an internal ring gear  256  provided on a second end of first gear set  250 . Each planetary gear is also splined to mesh with the external splines of locking motor output shaft  280 . Integrally situated and extending from a first end of the second gear set casing  260  is a port or interlock member  268 A, comprising a set of locking dogs, teeth, or similar locking extrusions, which can lock a port  258 , comprising a set of matable extrusions, provided on a second end of first gear set  250 . Projecting from a second end of gear set casing  260  is a port or interlock member  268 B, which is interlockable with extrusions on a planetary gear port  278 . In one embodiment, second gear set  260  is sleeved with a bronze bushing. As a result of shifting planet gear carrier  260  between a first and second position, an interlock  268  including interlock members  268 A/ 268 B provided on carrier  260  permits the axle  114 / 114 A to rotate in either a first or second direction, as described herein. 
         [0037]    Shifting between a forward direction, associated with a first rotation direction of wheel axle  114 / 114 A, and a reverse direction, associated with a second rotation direction of wheel axle  114 / 114 A, is advantageously achieved by linearly displacing planetary gear carrier  260  between a first position, thereby rotatably coupling or locking ports  258  and  268 A, and a second position, thereby rotatably coupling or locking ports  268 B and  278 . In reference to  FIGS. 7-9 , it should be noted that first positions and first ends are associated with the left direction of the drawing, and second positions and second ends are associated with the right direction of the drawing. Second gear set  260  may be aligned by sliding over an output shaft  248 . 
         [0038]    Linear displacement of second gear set  260  is achieved through an actuating system including actuation of at least one solenoid  242  held in alignment by inner plate  238 . The solenoids  242  illustrated are push-type and mounted substantially parallel to axle  114 / 114 A, however other known or to be developed pumps or actuators in place of push-type solenoids  242  may also be used, so long as the actuating component may actuate a force as described. Additional embodiments contemplate the actuators situated at an angle relative to the wheel axis, so long as the force of the actuator results in substantially linear displacement in the direction of the wheel axis. Using user control means not illustrated, such as an electrical switch at the handlebar of the vehicle, solenoids  242  are actuated to force an associated actuator member  244 , a solenoid plunger in the embodiment illustrated, from a first position to a second position along a substantially linear path in association with the wheel axis. In the embodiment illustrated, the substantially linear path is substantially parallel to the wheel axle, however other linear and nonlinear directions between the first and second positions are contemplated within the disclosure. Each plunger  244  is coupled to a thrust bearing plate  270  such that an actuation of solenoids  242  results in a displacement of plate  270  from the first position to the second position. It should be understood that certain safety interlocks may be provided, for example in cooperation with an onboard computer, to prevent shifting when the vehicle is in motion, or when an operating speed (RPM) of the motor is excessively high. 
         [0039]    Second gear set  260  is seated in a central aperture of plate  270  and is freely rotatable about the wheel axis, while plate  270  is rotationally fixed by a plurality of pins  272 , although plungers  244  may also act to rotationally fix plate  270  on their own or with the assistance of one or more pins  272 . A thrust bearing  276  is advantageously provided on each side of plate  270  to permit rotation of gear set  260  while advantageously resisting high and repetitive axial loadings that may be exerted during shifting between first and second positions, as well as natural forces exerted during operation of the vehicle; however other bearing types are contemplated within the disclosure. A spacer  266  may also be provided to maintain alignment of second gear set  260  with plate  270 . 
         [0040]    In order to shift from the second position back to the first position, solenoids  242  are deactuated, or depressurized in some embodiments, and biasing members or springs  274  exert their stored energy, acquired during displacement from first to second position, thereby pushing plate  270 , and thus second gear set  260 , back to the first position. Springs  274  may be provided at various points along the second side of plate  270 , including proximate to plungers  244 , pins  272 , a combination thereof, or other positions reasonably determined by a person of ordinary skill sufficient to force plate  270  from the second position to the first position. Where the springs are provided in a position opposite to plungers  244 , a pin  246  may be provided to restrict slippage or misalignment of spring  274 . In the embodiment illustrated, two (2) pins  272  and two (2) plungers  244  are illustrated, with a biasing member  244  associated with each. 
         [0041]    Two support frames  210  are provided on each end of gear set  200 , with inner plate  238  connected in between by a plurality of interlocking support spacers or pins  236 . In some embodiments, a screw  234  associated with each spacer  236  is used to secure or lock spacer  236  to end plates  210 . Frames  210  and plate  238  are rotationally fixed within housing  200 . The housing frame or shell  230  extends between frames  210 , situated or seated in a lip or groove at the edge of each frame  210 , however in some embodiments housing  230  envelops and extends over frames  210  as well. 
         [0042]    Frames  210  and inner plate  238  are rotationally stationary, with respect to rotation in a first or second direction about wheel axle  114 / 114   a , while other components rotate as described herein. First gear set  250  is rotatable by passing plate  238  through bore  290 . A bore bearing  294  is provided externally about first gear set  250  to help hold and maintain concentricity, and a thrust bearing  292  provided, along with a biased washer, to remove clearance. Rotatably coupled on a first end of first gear set  250  is a back cover  254 , a portion of which extends through frame  210  and is rotatable by means of boring  240 . As discussed above, second gear set  260  is rotatably passed through thrust bearings  276 , and planetary gears  262  are individually rotatable about their individual axis within second gear set  260 . Shaft  280  is rotatably driven by final drive  120 , and freely rotates while projecting through frame  210  by means of bearing  284 . 
         [0043]    Specifically in reference now to  FIGS. 7-9 , wheel axle  114   a  is rotatable, with respect to a wheel axis longitudinally extending through the wheel axle  114   a , in a forward direction when second gear set  260  is positioned in first position, and wheel axle  114   a  is rotatable in a reverse direction when second gear set  260  is in a second position. In an embodiment of the disclosure, locking shaft  280  is rotatably driven in a first direction, associated with the forward direction of rotation. Externally provided on shaft  280  is a series of grooves or splines in meshed communication with planetary gears  262 . The splines associated with shaft  280  extend over a sufficient length of the shaft to permit rotatable engagement between shaft  280  and planetary gears  262  in both first and second positions. 
         [0044]    In a first position, shaft  280  is rotated by final drive  120  in a first angular direction, illustrated as counter-clockwise. Shaft  280  applies an angular momentum thereby rotating gear set  260  and internally splined ring gear  256 , which are rotationally locked with each other with respect to rotation about the wheel axis through engagement between ports  258  and  268 A. In a second or reverse position, gear set  260  is rotationally fixed with respect to the wheel axis through engagement between ports  268 B and  278 . Accordingly, shaft  280  functions as a sun gear and rotates planetary gears  262  in a second direction, illustrated as clockwise, which in turn rotate internal ring gear  256  is a second direction. Thus, in first position ring gear  256  is rotated in a first direction and in second position ring gear  256  is rotated in a second direction. 
         [0045]    In both positions, the rotation of ring gear  256  results in rotation of first gear set  250  with respect to the wheel axis. Gear set  250  remains fixed in rotation to wheel axle  114 A in either the first or second position, thereby providing output rotation to wheel hubs  130 . In another embodiment, gear set  250  is coupled to an output shaft which rotates in connection with wheel axle  114 A. A series of spider gears  252 , advantageously functioning as a differential, are shown in the illustrated embodiment, however it should be understood that gear set  250  may be directly connected to an output shaft or wheel axle  114 / 114 A. 
         [0046]    In the reverse or second position, the gear ratio resulting in power transmitted to the output shaft  248  or wheel axle  114 A is advantageously lower than the gear ratio provided in the forward or first position. This reduced gear ratio is advantageously accomplished through utilization of planetary gears  262  in the second position. The gear ratio between an input rotation along shaft  280  and the output rotation to the axle  114 / 114 A may be calculated by means known to a person of ordinary skill in the art, however it should be clear that the lowered ratio in the second position permits more power to be transmitted to wheel axle  114 / 114 A and wheel hubs  130 . The advantageously enhanced gear ratio permits the vehicle to be driven in reverse over a ramped incline, such as backing the vehicle into a trailer bed, without difficulty. 
         [0047]    It is advantageous that reversing transmission  200  is applicable to standard or commonly obtained automobile wheel hubs  130 , bearings, and other components associated with the rear portion of the vehicle. Wheel axle  114 / 114 A may be advantageously custom made from 4140 pre-hardened steel in order to accommodate the wheel hubs  130  designated by the customer, however the original axle  114  may be utilized as well in some embodiments. As such, the embodiments disclosed may be adapted to a variety of commercially sold motorcycles, including motorcycles based upon the metric system. 
         [0048]    The simplicity of the design permits the present embodiments of the disclosure to be installed substantially more quickly and readily than “trike” conversions of the prior art. For example, trike builders typically estimate eight (8) to fourteen (14) hours of installation time, while the embodiments of the present disclosure can be installed in less than one hour. An installation of the reverse system  200  is accomplished by replacing the bolts supporting the frame  210  and swing arm  110  as described herein, and adjusting or extending of the brake line (not shown), if needed. 
         [0049]    The advantageous simplicity of the embodiments disclosed is further apparent in that shifting may be accomplished through a single switch actuating and deactuating the solenoids  242 . The design is thus an improvement over lever operated reversing transmissions associated with gear modifications to the actual transmission of the automobile. The embodiments disclosed are also an improvement over designs including external starter motors which turn a ring gear, providing limited power in a reverse gear, as opposed to the lower gear ratio and enhanced power provided in the present disclosure, as described herein. 
         [0050]    All references cited herein are expressly incorporated by reference in their entirety. In addition, unless mention was made above to the contrary, it should be noted that all of the accompanying drawings are not to scale. There are many different features to the present invention and it is contemplated that these features may be used together or separately. Thus, the invention should not be limited to any particular combination of features or to a particular application of the invention. Further, it should be understood that variations and modifications within the spirit and scope of the invention might occur to those skilled in the art to which the invention pertains. Accordingly, all expedient modifications readily attainable by one versed in the art from the disclosure set forth herein that are within the scope and spirit of the present invention are to be included as further embodiments of the present invention. 
       REFERENCE LIST 
       [0000]    
       
         
           
               110  swing arm 
               112  pin 
               114  single wheel axle 
               114 A double wheel axle 
               120  final drive 
               122  suspension attachment point 
               124  pin 
               130  wheel hubs 
               150  support frame 
               200  reversible final drive 
               202  oil seal 
               204  clamp 
               210  support frame 
               220  constant velocity joint 
               230  housing shell 
               232  end plate 
               234  bolt 
               236  support spacer 
               238  inner plate 
               240  bearing 
               242  solenoid 
               244  solenoid plunger 
               246  pin 
               248  output shaft 
               250  first gear set 
               252  spider gears 
               254  back cover 
               256  internal ring gear 
               260  second gear set 
               262  planetary gears 
               264  snap ring 
               266  spacer 
               268 A port 
               268 B port 
               270  thrust bearing plate 
               272  pin 
               274  spring 
               276  thrust bearing 
               278  planetary gear port 
               280  locking shaft 
               282  o-ring 
               284  bearing 
               286  fastener 
               288  fastener 
               290  bore 
               292  thrust bearing 
               294  bore bearing