Steering apparatus and method for a tractor

Abstract

A tractor includes a motor, transmission, drive shaft and rear differential for driving the rear axles mounted on a main tubular frame of a variable configuration. Forwardly extendable telescoping tubular frame members are actuated by respective rams to selectively increase the wheel base between the front and rear wheels. The front and rear telescoping tubes supporting each of the wheels are selectively extendable to significantly increase the wheel width of the tractor; the axles for the rear wheels are commensurately extendable. A toolbar dependingly supported from the main frame in front of the cab permits the operator to view the operation of attached implements while driving. The toolbar may include a row guide causing the toolbar to move laterally as necessary to follow a row and the toolbar is connected to the steering mechanism to control the direction of travel of the tractor. The front wheels are pivotally mounted on the corresponding telescoping tubes to provide sufficient clearance to permit near 180° pivotal movement. The steering mechanism is capable of pivoting each front wheel through an angle of about 180° and establishes an appropriate geometric relationship between the front wheels to permit the tractor to turn about any center of rotation intersected by the common axis of rotation of the rear axle, including pivoting about either rear wheel, while maintaining the axis of rotation of each front wheel in intercepting relationship with the center of rotation. Moreover, the turn radius at the end of a row is minimal and can be further reduced by temporarily reducing the length of the frame. Various implements, including a toolbar, can be readily attached directly to the tubular frame at any location intermediate the front and rear axles, as necessary.

1 . An agricultural tractor comprising in combination:
 a) a tubular frame;   b) a support pivotally supported by said frame;   c) a first tube extending from said support for locating a first pivot mechanism associated with a first front wheel a distance from said frame;   d) a second tube extending from said support for locating a second pivot mechanism associated with a second front wheel a distance from said frame; and   e) a steering mechanism for pivoting each of said first and second front wheels from a location adjacent one side of the respective one of said first and second tubes to a location adjacent the other side of the respective one of said first and second tubes.   
   
   
       2 . The agricultural tractor as set forth in  claim 1 , including rear wheels mounted on said tractor and having a common axis of rotation, said first front wheel having a first axis of rotation, said second front wheel having a second axis of rotation, said steering mechanism including a plurality of linkages for causing the first and second axis of rotation to intersect one another along the common axis of rotation upon pivotal movement of said first and second front wheels. 
   
   
       3 . A method for steering an agricultural tractor to reduce plowing of the wheels, said method comprising the steps of:
 a) turning the left front wheel at a first rate for a left turn;   b) turning the right front wheel at a second rate for a left turn to maintain the axis of rotation of the left front wheel intercepted by the axis of rotation of the right front wheel at a location along the common axis of rotation of the rear wheels;   c) turning the left front wheel at the second rate for a right turn; and   d) turning the right front wheel at the first rate for a right turn to maintain the axis of rotation of the right front wheel intercepted by the axis of rotation of the left front wheel at a location along the common axis of rotation of the rear wheels.