Abstract:
A drivetrain for an amphibious vehicle for spacing a transmission apart from a motor to permit the relative positions of the motor and the transmission in the vehicle to be lowered. The drivetrain includes a separator shaft with first and second U-joints attached at its ends, an adaptor plate for coupling one of the U-joints to a motor flywheel, an adaptor hub, an adaptor shaft and a coupler. The drivetrain transfers rotational movement from the motor to the spaced-apart transmission.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     Not Applicable. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not Applicable. 
     BACKGROUND OF THE INVENTION 
     The present invention relates to a drivetrain for an amphibious vehicle and, more particularly, to a drivetrain which is located between a motor and a transmission such that the transmission may be spaced apart from the motor. 
     Amphibious vehicles present unique design challenges. Unlike cars and trucks which are designed specifically to be driven on the land and boats which are designed specifically to be driven on water, amphibious vehicles must be designed to handle both tasks equally well. When driven on land, the body of an amphibious vehicle must ride high enough off the ground to clear standard obstacles faced by all road vehicles. On the other hand, when the amphibious vehicle is driven in water, the vehicle must sit low enough in the water to be stable. The stability of the vehicle in water is increased as it&#39;s center of gravity is lowered. 
     One way to lower the center of gravity of the vehicle is to lower the relative positions of the mechanical items that drive the amphibious vehicle. One of the heaviest mechanical items in an amphibious vehicle is the motor. Another item which is substantially heavy is the transmission, which is connected to the motor. Consequently, it would be beneficial to lower the position of the motor and the transmission in the body of the vehicle. 
     In general, motors in amphibious vehicles are mounted in a front portion of the body or hull, as is common in cars and trucks. This arrangement allows for more room in the body of the vehicle for passengers and cargo than in situations where the engine is mounted towards the middle or rear of the amphibious vehicle. A drawback of this arrangement, however, is the configuration of the hull or body of the vehicle. As the underneath of the body must be watertight and solid to allow the amphibious vehicle to float, the bottom of the body or the hull must be designed to conform to the parts of the vehicle which must remain outside of the hull to allow the vehicle to move on land. In other words, the wheels and the axles of the vehicle must be located on the outside of the water tight body. So that the entire body does not have to be above the wheels, which would result in a vehicle with a extremely high center of gravity, contours are provided in the underneath side of the hull that permit the body to be lowered around and partially encompass portions of the wheels and axles. 
     One of the contours that is provided in the underneath side of the body is a channel which partially encompasses the front axle. This channel, like the axle it surrounds, is perpendicular to the longitudinal axis of the body and is located in a front portion of the vehicle. The motor and transmission combination is generally parallel to the longitude axis of the vehicle as a drive shaft extends from the transmission to the rear axle of the vehicle to supply the rear wheels with power. As the front axle channel protrudes up into the cavity in the front portion of the body where the motor and transmission sit, it presents a barrier to being able to lower the motor and transmission in the hull to lower the vehicle&#39;s center of gravity and increase it&#39;s stability. 
     Therefore, there is a need for a method of lowering the relative positions of the motor and the transmission in an amphibious vehicle while maintaining the presence of a axle channel in the front of the vehicle&#39;s hull. The present invention overcomes the drawbacks of the prior art and fills these and other needs. 
     BRIEF SUMMARY OF THE INVENTION 
     It is a general object of the present invention to lower the center of gravity in an amphibious vehicle, thereby increasing it&#39;s stability when driven in water. 
     It is an object of the present invention to increase the room available for people and cargo in the hull of an amphibious vehicle by lowering the relative position of the transmission. 
     Another object of the present invention is to provide a drivetrain that allows the transmission of a vehicle to be spaced apart from the motor. 
     A further object of the invention is to provide a drivetrain capable of transferring rotational motion from a motor to a transmission. 
     In order to overcome the above-stated problems and limitations, and to achieve the noted objects, there is provided a drivetrain having a separator shaft with first and second ends. The separator shaft is preferably connected to the motor on its first end by a first universal joint (“U-joint”) and an adaptor plate. The separator shaft is preferably connected to the transmission on its second end by a second U-joint, a coupler, an adaptor hub and an adaptor shaft. 
     Further objects, features, and advantages of the present invention over the prior art will become apparent from the detailed description of the drawings which follows, when considered with the attached figures. 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
     The objects and features of the invention noted above are explained in more detail with reference to the preferred embodiments illustrated in the attached drawing figures, in which like reference numerals denote like elements, and in which: 
     FIG. 1 is a side view of an amphibious vehicle having a portion thereof cut-away to show the drivetrain of the present invention; 
     FIG. 2 is a side view of drivetrain of the present invention; 
     FIG. 3 is a side view of a portion of the drivetrain of the present invention adjacent the transmission with portions thereof cut away; 
     FIG. 4 is a cutaway side view of the coupler of the drivetrain taken along line  4 — 4  of FIG. 6; 
     FIG. 5 is a side view of the adaptor shaft of the drivetrain; 
     FIG. 6 is an end view of the coupler of the drivetrain in the direction of line  6 — 6  of FIG. 4; and 
     FIG. 7 is an end view of the adaptor shaft of the drivetrain in the direction of line  7 — 7  of FIG.  5 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the drawings in more detail and initially to FIG. 1, numeral  10  generally designates an amphibious vehicle. The amphibious vehicle  10  has a motor  12  and a transmission  14  which are separated by and connected to each other by a drivetrain  16  of the present invention. 
     Looking now at FIG. 2, in general, the drivetrain  16  includes a separator shaft  18  and preferably also includes a first U-joint  20 , a second U-joint  22 , an adaptor plate  24 , an adaptor hub  26 , an adaptor shaft  27  and a coupler  28 . The shaft  18  has a first end  30  and a second end  32 . The shaft also has a slip joint  34  to permit the shaft  18  to be lengthened and shortened as needed during rotation. 
     The first end  30  of the shaft  18  is coupled with the motor  12  preferably by the use of the first U-joint  20 . The first U-joint is of common construction and includes a flange yoke  36  and a sliding yoke  38 . The two yokes  36 ,  38  are connected by a journal  40 . 
     In the prior art, the motor  12  has a crankshaft which is bolted directly to a flywheel in the transmission. In the present situation, however, the motor  12  has a motor flywheel  42 . The motor flywheel  42  is coupled with the flange yoke  36  of the first U-joint  20  by way of the adaptor plate  24 . 
     The second U-joint  22  is preferably coupled with the second end  32  of the shaft  18 . Like the first U-joint  20 , the second U-joint  22  includes a flange yoke  46  and a journal  48 . The second U-joint  22 , however, has a fixed yoke  50  instead of a sliding yoke like the sliding yoke  38  found in the first U-joint  20  as a second sliding yoke is not necessary. It should be noted at this time that while the first U-joint  20  having the sliding yoke  38  has been placed at the first end  30  of the shaft  18 , the shaft could be flipped end for end or the U-joints  20 ,  22  could be reversed. 
     The adaptor hub  26  is preferably bolted directly to a transmission cover plate  44  has a disk  52  and a body  54 . The disk  52  is coupled with the transmission cover plate  44  via bolts  56 . The body  54  has a first seat  58  for receiving a first set of bearings  60  at a distal end  62  of the hub  26 . The hub  26  also has a second seat  64  for receiving a second set of bearings  66  located at least partially in the disk  52 . The transmission cover plate  44  includes a through bore  68  which cooperates with the second seat  64  of the adaptor hub to retain the second set of bearings  66 . 
     The transmission  14  has a transmission flywheel  70  which is generally bolted directly to the crank shaft of the motor  12 . In the present invention, however, the transmission flywheel  70  is bolted to the adaptor shaft  27  with bolts  71 . The adaptor shaft  27  has a base  72  and a rod member  74  which extends generally perpendicular to the base  72 . The base  72  contains a recess  76  for use as a centering port for a torque convertor in the transmission  14  and a plurality of bolt holes  77  for receiving the bolts  71 . The rod member  74  preferably has four sections of differing diameters. The first section  78  of the rod member  74  abuts the base  72  at a proximal end  80 . The proximal end  80  of the first section also includes a portion of the recess  76 . The first section has a distal end  82  opposite the proximal end  80 . 
     The rod member  74  has a second section  84  with a proximal end  86  and a distal end  88 . The proximal end  86  of the second section  84  abuts the distal end  82  of the first section. The second section  84  also includes a proximal bearing portion  90 , a distal bearing portion  92  and an intermediate portion  94 . The proximal bearing portion  90  is sized to receive the second set of bearings  66  and the distal bearing portion  92  is sized to receive the first set of bearings  60 . While the diameter of the intermediate portion may be slightly less than the diameters of the proximal bearing portion  90  and the distal bearing portion  92 , the diameter of the second section  84  is less than the diameter of the first section  78 . This step down in diameter from the first section  78  to the second section  84  presents a first shoulder  96 . This first shoulder  96  presents a surface upon which the second set of bearings  66  may rest. 
     The rod member  74  has a third section  98  with a proximal end  100  and a distal end  102 . The proximal end  100  of the third section  98  abuts the distal end  88  of the second section  84 . The third section  98  has a treaded surface  104 . The diameter of the third section  98  is less than the diameter of the second section  84  and thus presents a second step down in diameter of the rod member  74  and a second shoulder  106 . 
     The rod member  74  has a fourth section  108  which has a proximal end  110  and a distal end  112 . The proximal end  110  of the fourth section  108  abuts the distal end  102  of the third section  98 . The fourth section also preferably presents a threaded surface  114  and has a diameter which is less than the diameter of the third section  98 . Consequently, the smaller diameter of the fourth section presents a third step down in diameter for the rod member  74  and presents a third shoulder  116 . 
     The coupler  28  has a base  118  and a body  120 . The base  118  preferably has four bolt holes  122  to allow the coupler  28  to be bolted to the flange yoke  46  of the second U-joint  22  via bolts  124 . The coupler  28  includes a through bore  126  along a longitudinal axis of the coupler  28 . The through bore  126  is internally threaded such that the coupler  28  may threadably receive the threaded surface  114  of the fourth section  108  of the adaptor shaft  27 . 
     The body  120  of the coupler  28  preferably has a proximal end  128  and a distal end  130 . The proximal end  128  abuts the base  118  while the distal end  130  abuts the third shoulder  116  of the adaptor shaft  27  when the adaptor shaft  27  is threadably received in the coupler  28 . It should be noted that the threads of the fourth section  108  of the adaptor shaft  27  and the threads of the through bore  126  in the coupler  28  should be arranged such that the rotary motion imparted on the separator shaft  18  by the motor  12  is in a direction that would continue to screw the coupler  28  onto the adaptor shaft  27 . In other words, if the coupler  28  must rotate in a clockwise direction to screw onto the adaptor shaft  27 , the separator shaft  18  must also rotate a clockwise direction. Otherwise, the rotary motion of the separator shaft  18  will attempt to unscrew the coupler  28  from the adaptor shaft  27  during use of the motor  12 . While the rotational motion of the shaft  18  in the same rotational direction required to screw the coupler  28  on to the adaptor shaft  27  works to make sure that the distal end  130  of the body  120  of the coupler  28  stays in contact with the third shoulder  116  of the adaptor shaft  27 , the body  120  of the coupler  28  preferably also includes a bore  132  for receiving a set screw  134 . The set screw  134  helps to lock the coupler  28  onto the fourth section  108  of the adaptor shaft  27 . 
     The drivetrain  16  also includes a locking nut  136 . The locking nut  136  is threadably received on the third section  98  of the adaptor shaft  27  and is used to hold the first set of bearings  60  in the first seat  58  of the adaptor hub  26 . The locking nut  136 , by being threadably received on the adaptor shaft  27 , can be used to adjust the compression pressure applied to the first and second sets of bearings  60 ,  66 . The locking nut  136  preferably includes a set screw  138  which may be tightened once the locking nut has been screwed down far enough to present the desired compression pressure on the first and second sets of bearings  60 ,  66  to cinch the locking nut  136  onto the adaptor shaft  27  to secure the locking nut  136  in position. 
     The amphibious vehicle  10  has a body  140  with a bottom portion or hull  142 . The hull  142  has a channel  144  therein to accommodate a front axle of the vehicle  110 . By inserting the drivetrain  16  between the motor  12  and the transmission  14 , the relative positions of the motor  12  and the transmission  14  in the body  140  of the vehicle  10  may be lowered as the motor  12  may be moved forwardly of the channel  140  and the transmission  14  may be moved rearwardly of the channel  144 . The drivetrain  16 , in turn, spans between the motor  12  and the transmission  14  over the channel  144 . 
     From the foregoing it will be seen that this invention is one well adapted to attain all ends and objects hereinabove set forth together with the other advantages which are obvious and which are inherent to the structure. It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims. 
     Since many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative of applications of the principles of this invention, and not in a limiting sense.