Abstract:
A rear end gear box for a racing car has the swivel coupler and the bearing rotatably supporting the swivel coupler mounted within the rear end housing so that oil within the rear end housing will lubricate the swivel coupler and its bearing. The input shaft delivering rotational power from the engine is offset to the right of the driven shaft mounted within the rear end housing so that the center of gravity of the rear end is shifted to the left of the car centerline to increase stability of the car in turns. The recessed swivel coupler has an extended operating life due to increase stability and rigidity provided by the support from the housing structure. The cover for the back end of the rear end structure where the transfer gears are located is provided with an O-ring to facilitate a quick change of the transfer gears.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates generally to a rear end for a racing car used in sprint racing, and, more particularly, to a rear end having offset drive gears for transferring rotational power from the engine to the rear axle of the racing car. 
     Sprint cars and smaller racing cars are powered by an engine supported in a frame and connected to a rear end gear box that transfers rotational power to the rear wheels of the racing car. The rear end gear box has a disconnect mechanism that interrupts the transmission of rotational power to the rear wheels. When the racing car is being operated on the race track, the rear end gear box is engaged to transfer power from the engine. When the operator desires to stop the movement of the racing car, the rear end gear box is operably disconnected from the engine so that rotational power is no longer being transferred. 
     In current state of the art racing car rear ends, the drive shaft connected between the engine and the rear end gear box transfers a substantial amount of power to the rear end. In some sprint cars, the engine can produce 950 horsepower to drive the racing car which may weigh only about 1300 pounds. The torque involved in the transfer of this much power, along with the external forces encountered during the racing of the sprint car, results in a movement of the drive shaft relative to the rear end. This slight “whipping” and vibrational movement of the drive shaft can place substantial wear on the bearings housed within the rear end. To minimize the wear problem, a swivel coupling has been adopted so that the swivel coupling can absorb the movement of the drive shaft without causing substantial wear problems. 
     The placement of a swivel coupling into the engine end of the rear end gear box causes spatial problems. Because of the ring gear contained within the rear end gear box to drive the rear axle of the racing car, the swivel coupling and a bearing for rotationally supporting the swivel coupling are located on the outside of the rear end housing. As a result, the bearing has to be a sealed bearing that contains its own lubricant, since the bearing is not in flow communication with the oil flow within the rear end housing. If the swivel coupling were located inside the conventional gear box, the interior portion of the swivel coupling would interfere with the ring gear. Accordingly, the swivel coupling is positioned outside the rear end housing where stability and rigidity of the swivel coupling is compromised. Furthermore, the swivel coupling is not lubricated from the oil within the rear end housing. 
     Sprint racing cars only turn to the left when racing around the track. Manufacturers have employed different strategies for shifting the center of gravity of the racing car to the left of the car centerline. One concept was to shift the engine to the left of the car centerline; however, the resulting coupling of the drive shaft between the engine and the rear end placed too much stress on the swivel coupler, reducing the life of the swivel coupler. Extending the life of the bearings and the swivel coupler is important to successful operation of the racing cars. If the swivel coupler or the bearings fail during a race, the race car is finished for the night. 
     Therefore, it would be desirable to provide a rear end structure for a racing car that would be operable to recess the swivel coupler and the associated bearing internal of the rear end housing so that the swivel coupler and the bearing would be lubricated by the oil within the rear end housing. It would also be desirable to provide a rear end structure for a racing car that results in a shifting of the center of gravity of the racing car to the left to increase the stability of the racing car while make turns on the race track. 
     SUMMARY OF THE INVENTION 
     It is an object of this invention to provide a rear end gear box for a racing car in which the swivel coupling connecting the drive shaft from the engine to the rear end drive mechanism is mounted within the rear end housing. 
     It is another object of this invention to provide a rear end structure that shifts the center of gravity of the racing car to the left of the centerline of the car. 
     It is still another object of this invention to offset the drive shaft relative to the driven shaft within the rear end gear box structure. 
     It is a feature of this invention that the swivel coupler is supported internally of the rear end housing. 
     It is another feature of this invention that the bearing associated with supporting the swivel coupler is also mounted internally of the rear end housing. 
     It is an advantage of this invention that the swivel coupler and the bearing rotatably supporting the swivel coupler are lubricated by the oil within the rear end gear box housing. 
     It is another advantage of this invention that the supporting of the swivel coupler within the rear end housing increase the stability and the rigidity of the swivel coupler. 
     It is still another advantage of this invention that the operative life of the swivel coupler is increased by supporting the swivel coupler within the rear end gear box housing. 
     It is still another feature of this invention that the drive shaft is located in the rear end housing at an offset from a vertical plane extending through the center of the rear end housing in alignment with the driven shaft mounted within the rear end gear box housing. 
     It is yet another feature of this invention that the positioning of the drive shaft of the rear end gear box on the centerline of the racing car in alignment with the engine drive shaft places the center of gravity of the rear end structure to the left of the centerline of the racing car. 
     It is yet another advantage of this invention that rear end gear box shifts the center of gravity of the racing car to the left of the car centerline. 
     It is still another advantage of this invention that the rear end housing increases the stability of the racing car while turning around the race track. 
     It is still another feature of this invention that the cover over the transfer gears at the back end of the rear end gear box structure incorporates an O-ring to seal the cover against the rear end gear box housing. 
     It is still another advantage of this invention that the use of the O-ring allows for the cover to be closed quickly for a quick change of the transfer gears. 
     It is yet another object of this invention to provide a rear end gear box for a sprint racing car which is durable in construction, inexpensive of manufacture, carefree of maintenance, facile in assemblage, and simple and effective in use. 
     These and other objects, features and advantages are accomplished according to the instant invention by providing a rear end gear box for a racing car in which the swivel coupler and the bearing rotatably supporting the swivel coupler are mounted within the rear end housing so that oil within the rear end housing will lubricate the swivel coupler and its bearing. The input shaft delivering rotational power from the engine is offset to the right of the driven shaft within the rear end housing so that the center of gravity of the rear end is shifted to the left of the car centerline to increase stability of the car in turns. The recessed swivel coupler has an extended operating life due to increase stability and rigidity provided by the support from the housing structure. The cover for the back end of the rear end structure where the transfer gears are located is provided with an O-ring to facilitate a quick change of the transfer gears. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The advantages of this invention will be apparent upon consideration of the following detailed disclosure of the invention, especially when taken in conjunction with the accompanying drawings wherein: 
         FIG. 1  is a side elevational view of a rear end gear box housing incorporating the principles of the instant invention, the front or engine end of the rear end gear box being to the right side of the figure and the back end on the left side, the movement of the external shift lever being depicted in phantom; 
         FIG. 2  is a top plan view of the rear end gear box housing depicted in  FIG. 1 ; 
         FIG. 3  is an end elevational view of the engine end of the rear end gear box housing shown in  FIGS. 1 and 2 ; 
         FIG. 4  is a end elevational view of the back end of the rear end gear box housing opposite to the view of  FIG. 3 ; 
         FIG. 5  is a cross sectional view through the rear end gear box taken along lines  5 - 5  of  FIG. 3 , the drive components being depicted for transferring the rotational power from the engine of the racing car to the rear axle; 
         FIG. 6  is an enlarged partial cross-sectional view of the input driveline to depict the swivel coupling recessed into the input cowling of the housing; 
         FIG. 7  is an enlarged partial cross-sectional view of the input driveline to depict the shift coupler; 
         FIG. 8  is an enlarged elevational view of the shift coupler apparatus with the shift coupler in the “on” position; 
         FIG. 9  is an enlarged elevational view of the shift coupler apparatus similar to that of  FIG. 9 , but showing the shift coupler in the “off” position; 
         FIG. 10  is a plan view of the interior side of the cover for the transfer cowling to show the O-ring disposed within the cover; and 
         FIG. 11  is a cross-sectional view of the cover for the transfer cowling taken along lines  11 - 11 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings, a rear end gear box forming part of a racing car and incorporating the principles of the instant invention can best be seen. The rear end gear box  10  is deployed at the rear axle of a racing car, such as a sprint car, in which the engine (not shown) is connected directly to the rear end gear box  10  which is operable to transfer the rotational power from the engine to the rear axle to drive the racing car around the race track. Such racing cars do not utilize a multiple gear transmission between the engine and the rear end gear box  10 , as these racing cars only have two operating conditions, on and off. Accordingly, the rear end gear box  10  includes a shifter  19  that is operable to operatively connect the input from the engine to the rear axle, or to disconnect the input from the engine to the rear axle. 
     The rear end gear box  10  includes a housing  12  that includes a front input cowling  13 , a rear transfer cowling  14  and a central ring gear cowling  15 . The rear axle  16  of the racing car passes through the center of the ring gear cowling  15  and extends transversely therethrough to drive the rear wheels (not shown) on opposing sides of the rear end gear box  10 . The shifter  19  is mounted on the housing  12  near the transfer cowling  14 . The shifter  19  is operatively connected, such as via a push/pull cable (not shown) to a shift lever (not shown) deployed in the operator&#39;s cockpit to control the on/off operative function of the racing car. The rotative movement of the shifter  19  causes a linear movement of the shift mechanism ** within the rear end gear box  10 , as will be described in greater detail below. 
     The operation of the rear end gear box  10  is best seen in  FIG. 5 . The power input shaft  21  is part of the input driveline  20  connected directly to the engine (not shown) and delivers rotational power from the engine into the rear end gear box  10 . Because of the amount of power delivered from the engine and the operational loads associated with the movement of the racing car around a race track, the power input shaft  21  is subject to a substantial amount of vibration and movement. As depicted in  FIG. 6 , to minimize the damage caused for an oscillating power input shaft  21 , the power input shaft  21  is connected to a swivel coupler  25  that includes a coupling sleeve  26  mounted on the splines  22  at the end of the power input shaft  21 . The coupling sleeve  26  is formed with rounded crown splines  27  that accommodate slight movements of the input shaft  21  relative to the rear end  10  while engaged with the transfer coupler  28  that is rotatably supported within the front input cowling  13  by bearings  28   a  mounting in the housing  12 . A snap ring  29   a  retains the transfer coupler  28  against the bearing  29  and retains the swivel coupler  25  within the front input cowling  13 . The coupling sleeve  26  is secured within the transfer coupler  28  by a seal  26   a  secured by a snap ring to allow the movement of the coupling sleeve  26  relative to the transfer coupler  28 . 
     Thus, the power input shaft  21  rotatably drives the coupling sleeve  26 , through interengaged splines, and the coupling sleeve  26  drives the transfer coupler  28  which has an enlarged front end  28   a  to accommodate the movement of the rounded crown splines  27  of the coupling sleeve  26  and a smaller rearward end  28   b  projecting rearwardly of the bearing  29 . A transfer shaft  31  has a forward portion  32  received within the rearward end  28   b  of the transfer coupler  28  so that the rotation of the transfer coupler  28  drives the rotation of the transfer shaft  31 . 
     As best seen in  FIGS. 5 and 7 , the rearward end  33  of the transfer shaft  31  drives a shift coupler  35  which has a forward portion  36  supported by the bearings  36   a  and engaged with the rearward end  33  of the transfer shaft  31 . The shift coupler  35  also includes a linearly movable shift collar  37  having splines  37   a  engagable with the rearward splines  36   b  and being slidable over the stub shaft  39  rotatably supported by bearings  39   a . The shift collar  37  captures the internal shift lever  38  connected to the shifter  19  so that when the shifter  19  is pivoted the internal shift lever  38  slides the shift collar  37  on the stub shaft  39  to move the splines  37   a  on the shift collar into or out of engagement with the splines  36   b  on the forward portion  36  of the shift coupler  35 . 
     In operation, which is best seen in FIGS.  5  and  7 - 9 , the transfer shaft  31  rotatably drives the forward portion  35  of the shift coupler  35 . The stub shaft  39 , which carries the shift collar  37  thereon for sliding movement relative to the stub shaft  39  along splines formed on the stub shaft  39  so that the shift collar  37  transfers rotational power from the forward portion  36  of the shift coupler  35  to the stub shaft  39  when the shift collar  37  is slid into engagement with the rearward splines  37   b  of the forward portion  37  of the shift coupler  35 . When the shift collar  37  is moved out of engagement with the forward portion  36  of the shift coupler  35 , the driveline  20  is disconnected and rotational power cannot be transferred from the engine to the rear axle  16 . 
     Referring again to  FIG. 5 , the transfer cowling  14  houses the bearing  39   a  rotatably supporting the stub shaft  39  and also a second bearing  39   b  that also rotatably supports the stub shaft  39 . A drive gear  41  is mounted on the stub shaft  39  between the two stub shaft bearings  39   a ,  39   b  within the transfer cowling  14  for rotation with the stub shaft  39 . The drive gear is operatively engaged with a driven gear  42  mounted on a second stub shaft  43 , forming the output driveline  40 , which is supported by three bearings  43   a ,  43   b  and  43   c . The first bearing  43   a  is located in the transfer cowling  14  above the bearing  39   b  for the first stub shaft  39 . The second bearing  43   b  is located at the central portion of the stub shaft  43 , and the third bearing  43   c  is located at the inner distal end of the stub shaft  43 . 
     The second stub shaft  43  has the driven gear  42  supported within the transfer cowling  14  along with the drive gear  41  so that both the drive gear  41  and the driven gear  42  can be accessed quickly and easily by removing the cover  45  that is bolted to and sealed against the transfer cowling  14 . Preferably, as depicted in  FIGS. 10 and 11 , the cover  45  carries an O-ring  46  that seals the cover  45  when compressed against the peripheral ring of the transfer cowling  14 . The O-ring  46  provides an effective seal to prevent leakage of lubricating oil from the housing  12 , but is carried by the cover  45  so that the replacement of the cover  45  on the transfer cowling  14  does not require the manipulation of a conventional gasket that is placed between the cover  45  and the transfer cowling  14 . 
     Referring again to  FIG. 5 , the second stub shaft  43  also carries at the inner distal end a pinion  48  that is engagable with a ring gear  49  mounted within the ring rear cowling  15 . The ring gear  49  is affixed to the rear axle  16  to transfer rotational power thereto and affect a driving of the rear axle  16 . Accordingly, the driveline  20  transfers rotational power from the engine through the swivel coupling  25 , the shift coupler  35 , the interengaged transfer gears  41 ,  42  and the pinion  48  to drive the ring gear  49  and the rear axle  49 . 
     Placement of the swivel coupling  25  internally of the housing  12  would normally interfere with the rotation of the ring gear  49 . To allow the recessing of the swivel coupling  25  into the housing  12  to allow the housing  12  to provide a stable and rigid support of the swivel coupling  25 , the power input shaft  21  is offset to the right of the line of the second stub shaft  43  carrying the pinion  48 . Specifically, the center of the power input shaft  21 , as well as the transfer shaft  31  and the first stub shaft  39 , were rotated approximately 16 degrees about the centerline of the second stub shaft  43 , as is represented in  FIG. 4 . Accordingly, a vertical plane passing through the center of the first stub shaft  39  is offset to the right of a vertical plane passing through the center of the second stub shaft  43 . 
     Since the power input shaft  21  is properly mounted in direct longitudinal alignment with the engine, particularly due to the amount of power being transferred through the power input shaft  21 , the entire remaining mass of the rear end gear box  10  has the center of gravity shifted to the left, as compared to a conventional rear end gear box structure with the first and second stub shafts  39 ,  43  being vertically aligned. The shift in the center of gravity of the rear end gear box  10  has a resulting shift in the center of gravity of the entire racing car to the left of the longitudinal centerline of the racing car. As a consequence, the racing car has more stability in turns around the race track. 
     Recessing the swivel coupling  25  and the bearing  29  associated with the swivel coupling  25  into the housing  12  allows both the swivel coupling  25  and the bearing  29  to be lubricated by the oil within the housing  12 . This direct lubrication of the swivel coupling  25  and the bearing  29 , along with the more rigid support of the swivel coupling  25 , results in a longer operating life of the swivel coupling  25  and the bearing  29  compared to the conventional mounting of the swivel coupling externally of the housing  12 . 
     It will be understood that changes in the details, materials, steps and arrangements of parts which have been described and illustrated to explain the nature of the invention will occur to and may be made by those skilled in the art upon a reading of this disclosure within the principles and scope of the invention. The foregoing description illustrates the preferred embodiment of the invention; however, concepts, as based upon the description, may be employed in other embodiments without departing from the scope of the invention.