Off road vehicle apparatus and method

Abstract

A ground engaged vehicle includes a front portion and a rear portion joined by an articulation. The articulation rotates around a longitudinal axis. An engine drives a hydrostatic pump which drives four hydrostatic motors, each of the hydrostatic motors in operative engagement with one of four wheels. The wheels are on wheel mounts, each of the wheel mounts having a vertical axis around which one of the four wheels with one of the hydrostatic motors is turnable. A steering system turns the two wheels of the front portion in a first direction and the two wheels of the rear portion in an opposite direction. The steering system is powered by the hydrostatic pump. A pedal control system has a first pedal controlling driving the vehicle in a forward direction and a second pedal controlling driving the vehicle in a rearward direction.

1 . A ground engaged vehicle comprising: 
 a front portion;    a rear portion; said front and rear portion being joined by an articulation, said articulation rotating around a longitudinal axis;    an engine, said engine being mounted in one of said front or said rear portions, said engine being in operative engagement with a hydrostatic pump;    four wheels;    four hydrostatic motors, each of said hydrostatic motors in operative engagement with one of said four wheels;    four wheel mounts, each of said wheel mounts having a vertical axis around which one of said four wheels with one of said hydrostatic motors is turnable;    two of said wheel mounts mounting two of said four wheels and two of said four hydrostatic motors on said front portion and two of said wheel mounts mounting two of said four wheels and two of said four hydrostatic motors on said rear portion;    a hydrostatic drive system in operative engagement with said hydrostatic pump and with each of said hydrostatic motors;    a steering system to turn said two wheels of said front portion in a first direction and said two wheels of said rear portion in an opposite direction, said steering system being powered by said hydrostatic pump; and    a pedal control system having a first pedal controlling driving the vehicle in a forward direction and a second pedal controlling driving the vehicle in a rearward direction.    
   
   
       2 . A ground engaged vehicle comprising: 
 a wheeled front portion;    a wheeled rear portion;    a hydrostatic drive system driving at least one of said wheeled front and rear portions; and    an articulation between said wheeled front portion and said wheeled rear portion, said articulation allowing said wheeled front portion and said wheeled rear portion to roll relative to one another around a longitudinal axis of the vehicle, wherein said articulation is comprised of a first collar attached to said front wheeled portion and a second collar attached to said wheeled rear portion in a center tube operatively engaged with each of said collars.    
   
   
       3 . The vehicle of  claim 2  wherein said center tube has a sufficiently large diameter for at least one hydrostatic drive hose to travel between said wheeled front portion and said wheeled rear portion.  
   
   
       4 . The vehicle of  claim 2  wherein said center tube is threaded and fixed to one of said first or second collars wherein said rolling is by threaded engagement and rotation around said threaded engagement between the other of said first or second collars and said center tube.  
   
   
       5 . The vehicle of  claim 2  further comprising a plastic spacer between said wheeled front portion and said wheeled rear portion.  
   
   
       6 . The vehicle of  claim 5  wherein said wheeled front portion has a rear hull plate engaged in close cooperation with a front surface of said plastic spacer and said wheeled rear portion has a front hull plate engaged in close cooperation with a rear surface of said plastic spacer.  
   
   
       7 . The vehicle of  claim 6  wherein said close cooperation defines a space of less than 0.1 inches.  
   
   
       8 . The vehicle of  claim 2  wherein said roll is limited to about 90 degrees.  
   
   
       9 . The vehicle of  claim 8  wherein said range of motion for said articulation is between about 45 degrees of vertical on both sides.  
   
   
       10 . The vehicle of  claim 4  wherein said threaded engagement is comprised of truncated threads.  
   
   
       11 . The vehicle of  claim 2  wherein an alignment of said first collar, said second collar and said center tube is aligned with the use of a first timing mark and a second timing mark, said first timing mark being on said first collar and said second timing mark being on said second collar.  
   
   
       12 . A ground engaged vehicle comprising: 
 a front portion,    a rear portion, said front and rear portion being joined by an articulation, said articulation rotating around a longitudinal axis of said vehicle;    a hydrostatic drive system driving at least two wheels;    at least two wheels being mounted on one of said front portion or said rear portion and at least one other wheel being mounted on the other of said front portion or said rear portion; and    each of said wheels being mounted without suspension.    
   
   
       13 . The vehicle of  claim 12  wherein each of said wheel mounts is comprised of: 
 a vertical cylinder fixedly mounted to one of said front portion or said rear portion;    a vertical rod journaled into said cylinder such that said rod may rotate within said cylinder around a vertical axis; and    a wheel mounting bracket fixedly attached to said vertical rod and adapted for receiving a wheel mounting.    
   
   
       14 . The vehicle of  claim 12  wherein said wheel mount includes a bracket, said bracket being adapted for mounting a hydrostatic drive motor such that said hydrostatic drive motor is in driving operative engagement with a wheel mounted on said wheel mount.  
   
   
       15 . The vehicle of  claim 12  wherein said wheel mounts are further adapted for mounting disc brakes.  
   
   
       16 . The vehicle of  claim 12  wherein said mount includes a vertical rod mounted to rotate around a vertical axis, and a lever arm fixedly attached to a top end of said vertical rod and adapted for pivoting engagement with a steering linkage.  
   
   
       17 . The vehicle of  claim 12  further comprising 15 inch wheels being mounted on said wheel brackets.  
   
   
       18 . The vehicle of  claim 12  further comprising tires mounted on wheels mounted on said wheel mounts, said tires being adapted to operate with less than 10 pounds psi of pressure therein.  
   
   
       19 . A ground engaged vehicle comprising: 
 a front portion said front portion having two wheels;    a rear portion, said rear portion having two wheels;    an articulation connecting said front portion and said rear portion, said articulation allowing said front and rear portions to rotate relative to one another around a longitudinal axis of the vehicle;    a hydrostatic drive system, said hydrostatic drive system driving each of four hydrostatic motors being operatively engaged with each of said four wheels.    
   
   
       20 . The vehicle of  claim 19  wherein said hydrostatic drive system is driven through hydraulic hoses, said hoses operatively connecting a pump with said hydrostatic motors, said pump being driven by an engine, wherein said pump and engine are in one of said front or rear portions and said hoses precede to the other of said front or rear portions through said articulation.  
   
   
       21 . The vehicle of  claim 19  wherein said hydrostatic drive system powers four wheels in diagonal pairs.  
   
   
       22 . The vehicle of  claim 19  wherein said hydrostatic drive system has a low gear and a high gear.  
   
   
       23 . The vehicle of  claim 19  wherein said hydrostatic drive system has a high gear and a low gear in each of a forward and a reverse direction.  
   
   
       24 . The vehicle of  claim 19  wherein said hydrostatic drive system has a low gear and a high gear, said hydrostatic drive system driving each of said hydrostatic motors in diagonal pairs in said low gear and said hydrostatic drive system driving all four hydrostatic motors in said high gear.  
   
   
       25 . The vehicle of  claim 19  wherein said hydrostatic drive system drives a first diagonal pair of said four hydrostatic motors with a first fluid volume, thereafter returning the first fluid volume to a hydrostatic pump and simultaneously drives the opposite diagonal pair of hydrostatic motors with a second fluid volume, thereafter returning said second fluid volume to said hydrostatic pump.  
   
   
       26 . The vehicle of  claim 19  wherein when in a low gear, said hydrostatic drive system drives a first diagonal pair of said four hydrostatic motors with a first fluid volume, thereafter returning the first fluid volume to a hydrostatic pump and simultaneously drives the opposite diagonal pair of hydrostatic motors with a second fluid volume, thereafter returning said second fluid volume to said hydrostatic pump; and when in a high gear a single volume of fluid drives all four hydrostatic motors before being returned to pump.  
   
   
       27 . The vehicle of  claim 19  further comprising a valve assembly, said valve assembly having two intake ports and four output ports, said valve assembly having a first position and a second position, said first position directing hydrostatic fluid out of a first pair of output ports and said second position driving a hydrostatic fluid out of a second pair of output ports.  
   
   
       28 . The vehicle of  claim 27  wherein when said valve assembly is in said first position a first volume of hydrostatic fluid is directed to a first diagonal pair of said hydrostatic motors and then returned to the pump and a second volume of hydrostatic fluid is directed to an opposite diagonal pair of hydrostatic motors and then returned to the pump.  
   
   
       29 . The vehicle of  claim 27  wherein when said valve assembly is in a second position a single fluid volume is directed to all four hydrostatic motors before being returned to the pump.  
   
   
       30 . The vehicle of  claim 19  further comprising a flow divider in operative communication to receive pressurized fluid from a pump and in operative communication to direct fluid to diagonal pairs of hydrostatic motors.  
   
   
       31 . The vehicle of  claim 30  wherein said valve assembly divides fluid when said vehicle is moving in a forward direction and said flow divider combines fluid when said vehicle is moving in a reverse direction.  
   
   
       32 . A ground engaged vehicle comprising: 
 a front portion having two wheels; a rear portion having two wheels;    an articulation between said front portion and said rear portion, said articulation allowing said front portion and said rear portion to rotate relative to one another around an axis longitudinal to the vehicle;    a hydrostatic drive system; and    each of said four wheels being steerable.    
   
   
       33 . The vehicle of  claim 32  wherein said two wheels on said front portion are steerable by a front steering linkage and said second two wheels on said rear portion are steerable by a rear steering linkage; wherein said front steering linkage and said rear steering linkage are coordinated by a hydrostatic powering steering system.  
   
   
       34 . The vehicle of  claim 32  wherein when said front two wheels on said front portion turn in a first direction, said rear two wheels on said rear portion turn in an opposite direction.  
   
   
       35 . The vehicle of  claim 32  wherein said front steering linkage for said two wheels on said front portion is coordinated with said rear steering linkage for said two wheels on said rear portion by a trapped a fluid volume.  
   
   
       36 . The vehicle of  claim 32  wherein said two wheels on said front portion are connected to each other by a front tie rod, said front tie rod having a first end and second end, each of said first and second ends of said front tie rod being pivotably attached to a front lever arm, each of said lever arms being operatively engaged to turn each of said two wheels of said front portion, said front tie rod being driven by a front two way piston and cylinder assembly; 
 said two wheels on said rear portion are connected to each other by a rear tie rod, said rear tie rod having a first end and second end, each of said first and second ends of said rear tie rod being pivotably attached to a front lever arm, each of said lever arms being operatively engaged to turn each of said two wheels of said rear portion, said rear tie rod being driven by a rear two way piston and cylinder assembly;    said each of said front and rear two way cylinder and piston assemblies having an active chamber, one of said active chambers receiving pressurized fluid from said power steering system while the other of said front or rear active portions exhausts fluid to return to said power steering system;    each of said front and rear piston and cylinder assemblies having a passive portion each of said front and rear passive portions being connected by a hydrostatic hose, and said first and second passive portions and said hose being in operative communication to trap a volume of fluid such that pressurization of a first active portion of a first piston cylinder assembly drives said trapped fluid volume into said second passive portion of said second piston cylinder assembly such that when a first piston cylinder assembly is driven to turn a first pair of wheels in a first direction, said second piston cylinder assembly is driven to drive a second pair of wheels in an opposite direction.    
   
   
       37 . The vehicle of  claim 32  wherein said hydrostatic hose connected to said first and second passive sections travels through said articulation.  
   
   
       38 . The vehicle of  claim 32  wherein said power steering system is driven through a charge pump.  
   
   
       39 . A ground engaged vehicle comprising: 
 a front portion;    a rear portion;    an articulation between said front portion and said rear portion, said articulation allowing said front portion and said rear portion to rotate relative to one another around an axis longitudinal to said vehicle;    a hydrostatic drive system powering at least two wheels on one of said front or rear portion and at least one wheel on the other of said front or rear portion;    said hydrostatic drive system having a forward direction and a rear direction, each of said forward and rear directions being powered by said hydrostatic drive system; and    a pedal assembly having a first pedal and a second pedal wherein depression of said first pedal drives said vehicle in a forward direction and depression of a second pedal drives said vehicle in a rearward direction.    
   
   
       40 . The vehicle of  claim 39  wherein said pedal assembly includes a lever, a first side of said lever being operatively connected to a forward drive control of said hydrostatic drive system and a second end of said lever being operatively connected to a rearward drive of said hydrostatic drive system.  
   
   
       41 . The vehicle of  claim 39  wherein said lever arm of said pedal assembly is a disc rotating around an axis, said disc having a first ear and a second ear, said ears also rotating around said axis, said rotation of said ears around said axis comprising said lever.  
   
   
       42 . The vehicle of  claim 39  wherein said pedal assembly is comprised of teeth on one of said pedals or said disc and slots on the other of said pedals or said disc.  
   
   
       43 . The vehicle of  claim 42  wherein said teeth of each of said pedals are on an arched surface.  
   
   
       44 . The vehicle of  claim 39  wherein said pedal assembly is configured such that said pedals rotate around an axis that is perpendicular to an axis of rotation of said lever.  
   
   
       45 . The vehicle of  claim 42  wherein said teeth on said pedals engage said slots in said disc, each of said slots being configured such that the sides of said slots receiving pressure from said teeth of said pedals are convex inwards.  
   
   
       46 . The vehicle of  claim 39  wherein said pedal assembly further comprises a locking pin.  
   
   
       47 . The vehicle of  claim 1  further comprises at least two cooling ports for an engine compartment, said engine compartment housing an internal combustion engine in operative engagement with a pump for said hydrostatic drive system.