Tractor with rear castor wheels

摘要

A hydrostatic agricultural tractor has front ground wheels mounted on the frame at fixed angles parallel to each other and parallel to a center line of the frame and rear ground wheels mounted on a respective castor, with each of the front ground wheels being driven by a respective drive motor which allows variable speed in both the first and second directions such that steering of the tractor is effected by a differential in speed between the front wheels with the rear wheels following the steering in a castoring action. A pair of damper cylinders is provided each connected between a bracket on a rear axle of the frame and a lever in the castor plane of the castor so as to provide a damping force tending to restrict rotation of the respective second wheel about the respective vertical pivot axis with the damping force at a maximum value when the rear wheels are parallel to the center line in either the forward or reverse directions.