Abstract: A vehicle with a total power fluid system includes a pair of drive wheels, variable displacement, fluid motors driven by an engine driven, variable displacement, fluid pump. The motor displacements are controlled by operator speed input and speed sensing controls, and the pump displacement is controlled by a pressure sensing pressure control. A vehicle steering control includes an operator steering input control connected to a steerable wheel control for actuating a valve for holding, turning, or castering fluidly steerable wheels which are capable of turning the vehicle. The operator steering input control is further connected to the operator speed input controls to slow the turn-side drive wheel motor during either a steerable wheel controlled or an emergency, drive wheel controlled turn. During either an electrical failure or a hydraulic failure sensed by the inability of the steerable wheels to follow the operator steering input control, the valve will be actuated to caster the steerable wheels.