Feedback controlled hydraulic valve system

A system for controlling the flow of hydraulic fluid to hydraulic actuator means, comprising fluid actuator means, a fluid pressure operated four-way main valve having ports, service lines connected to said ports and extending to said actuator means, a supply line and a tank return line, a pilot valve for controlling said main valve, said main valve regulating the flow of fluid to the actuator means, electrical input means for an electrical demand input signal, flow sensing means for producing an electric feedback signal dependent on the rate of fluid flow to the actuator means, and means for comparing the feedback signal with the demand signal and for operating the pilot valve accordingly, in which the flow sensing means comprise a flow sensing variable orifice means located in a port of the main valve to which is connected one of said fluid service lines to said actuator means, to measure fluid flow in said one fluid line by a pressure differential across said flow sensing orifice, and pressure transducer means hydraulically connected to opposite sides of said flow sensing orifice of said flow sensing device to receive and convert the generated pressure differential into the electric feedback signal such that the feedback signal is developed by the pressure differential across the orifice and results in a feedback signal even when the fluid flow is insufficiently high to overcome frictional forces on the movable element and the preload on the flow sensing means.