An hydraulic control system is disclosed which comprises a fluid reservoir (14), a variable displacement pump (12) having a fluid input connected to the reservoir and a fluid output, and a fluid pressure actuated displacement of the pump. A control valve (18) is connected to the fluid output of the variable displacement pump and to the reservoir and is adapted to control the flow of fluid to a fluid actuated device. The control valve includes means (44, 50, 52, 54, 56) for regulating flow of a signal fluid provided either by a constant displacement pump (46) or a pressure actuated flow control valve (47). A sensor valve (58) is placed in fluid communication with the signal fluid, the displacement control mechanism, and the reservoir for placing the signal fluid in communication with the displacement control mechanism or for placing the displacement control mechanism in communication with the reservoir, in response to changes in the pressure of the signal fluid, thereby controlling the displacement of the pump in response to the magnitude of the pressure of the signal fluid.