Abstract: Actuator control system includes two parallel connected orifices between a pair of fluid passages providing communication between an actuator and a flow control valve. Relief valves in series with the respective orifices block fluid flow through the orifices at low differential pressures between the fluid passages, thereby preserving the original high pressure gain of the control valve in a region about valve null. At higher differential pressures outside the valve null region, the relief valves open to permit restricted flow through the respective orifices to reduce the pressure gain of the control valve in a region outside the valve null region, which effectively reduces the stiffness of the control valve.

Abstract: Flow control valve includes angled metering ports in the valve sleeve for directing the momentum of the fluid flow against the respective valve flow metering edges in a direction producing an opening reaction force on the valve upon initial valve opening in opposition to the usual axial flow forces tending to close the valve to reduce the flow force gain acting on the valve. Preferably, the angled metering ports are disposed at an angle of approximately 45.degree. or greater from a line perpendicular to the valve axis. Also, a single set of circumferentially spaced angled metering ports is desirably provided for each return or high pressure flow path for producing the desired opening reaction force on the valve.