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.