Vehicle Having Twin Transmissions For Driving Respective Wheels

Abstract

A vehicle comprises a vehicle frame, a prime mover mounted on the vehicle frame, a laterally turnable wheel disposed at one side of the vehicle frame, a pair of drive wheels disposed at the other side of the vehicle frame, a steering operation device, a traveling operation device for setting the traveling speed and direction of the vehicle, and a pair of transmissions for controlling the rotary speed and direction of the respective drive wheels. The transmissions are operationally connected with the steering operation device so as to create a difference of rotary speed between the drive wheels according to operation of the steering operation device. The transmissions are operationally connected with the traveling operation device so as to drive the drive wheels in a common rotary direction from their stationary state according to operation of the traveling operation device. A clutch is interposed between the transmissions so as to connect the drive wheels with each other when the steering operation device is set in a straight traveling position. Based on setting of a switching device for switching the traveling direction of the vehicle between forward and rearward, a reverser decides the rotational direction of the drive wheels.

1 . A vehicle comprising: 
 a prime mover;    a pair of left and right steerable wheels;    a steering operation device for steering the pair of left and right steerable wheels;    a pair of left and right gear assemblies interposed between the steering operation device and the respective left and right steerable wheels, wherein, in each of the gear assemblies, a first non-circular gear operatively connected to the steering operation device meshes with a second non-circular gear operatively connected to each of the left and right steerable wheels;    a pair of left and right unsteerable driving wheels;    a speed control operation device for controlling rotational speeds of the unsteerable driving wheels; and    a pair of continuously variable transmissions driven by the prime mover so as to drive the respective unsteerable driving wheels, wherein the speed control operation device is operatively connected to the continuously variable transmissions so as to substantially evenly control output rotational speeds of the continuously variable transmissions, and wherein the steering operation device is operatively connected to the continuously variable transmissions so that a differential rotational speed of the unsteerable driving wheels is increased according to increase of an operation degree of the steering operation device.    
   
   
       2 . The vehicle according to  claim 1 , wherein the speed control operation device is a foot pedal, and wherein the steering operation device is a steering wheel.  
   
   
       3 . The vehicle according to  claim 1 , wherein the continuously variable transmissions are operatively connected to the speed control operation device and the steering operation device so that a turning direction of the vehicle coincides to an operation direction of the steering operation device regardless of whether the speed control operation device is operated for forward traveling of the vehicle or for backward traveling of the vehicle.  
   
   
       4 . A vehicle comprising: 
 a prime mover;    a pair of left and right steerable wheels;    a steering operation device for steering the pair of left and right steerable wheels;    a pair of left and right gear assemblies interposed between the steering operation device and the respective left and right steerable wheels, wherein, in each of the gear assemblies, a first non-circular gear operatively connected to the steering operation device meshes with a second non-circular gear operatively connected to each of the left and right steerable wheels;    a pair of left and right unsteerable driving wheels;    a speed control operation device for controlling rotational speeds of the unsteerable driving wheels; and    a pair of hydrostatic continuously variable transmissions driven by the prime mover so as to drive the respective unsteerable driving wheels, wherein the speed control operation device is operatively connected to the hydrostatic continuously variable transmissions so as to substantially evenly control output rotational speeds of the hydrostatic continuously variable transmissions, and wherein the steering operation device is operatively connected to the hydrostatic continuously variable transmissions so that a differential rotational speed of the unsteerable driving wheels is increased according to increase of an operation degree of the steering operation device.    
   
   
       5 . The vehicle according to  claim 4 , wherein the speed control operation device is a foot pedal, and wherein the steering operation device is a steering wheel.  
   
   
       6 . The vehicle according to  claim 4 , wherein the hydrostatic continuously variable transmissions are operatively connected to the speed control operation device and the steering operation device so that a turning direction of the vehicle coincides to an operation direction of the steering operation device regardless of whether the speed control operation device is operated for forward traveling of the vehicle or for backward traveling of the vehicle.  
   
   
       7 . A vehicle comprising: 
 a prime mover;    a pair of left and right steerable wheels;    a steering operation device for steering the pair of left and right steerable wheels;    a pair of left and right gear assemblies interposed between the steering operation device and the respective left and right steerable wheels, wherein, in each of the gear assemblies, a first non-circular gear operatively connected to the steering operation device meshes with a second non-circular gear operatively connected to each of the left and right steerable wheels;    a pair of left and right unsteerable driving wheels;    a speed control operation device for controlling rotational speeds of the unsteerable driving wheels; and    a pair of hydraulic units for driving the respective unsteerable driving wheels, each of the hydraulic units including a variable displacement hydraulic pump driven by the prime mover and a fixed displacement hydraulic motor fluidly connected to the hydraulic pump so as to drive the corresponding unsteerable driving wheel, wherein the speed control operation device is operatively connected to the hydraulic pumps so as to substantially evenly control output rotational speeds of the hydraulic motors, and wherein the steering operation device is operatively connected to the hydraulic pumps so that, as an operation degree of the steering operation device is increased, a displacement of one hydraulic pump is increased, and simultaneously, a displacement of the other hydraulic pump is reduced, so as to increase a differential rotational speed of the unsteerable driving wheels.    
   
   
       8 . The vehicle according to  claim 7 , wherein the speed control operation device is a foot pedal, and wherein the steering operation device is a steering wheel.  
   
   
       9 . The vehicle according to  claim 7 , wherein the hydraulic pumps are operatively connected to the speed control operation device and the steering operation device so that a turning direction of the vehicle coincides to an operation direction of the steering operation device regardless of whether the speed control operation device is operated for forward traveling of the vehicle or for backward traveling of the vehicle.