Valve construction

Claim 1

A ROTARY SERVO VALVE FOR A SEPARATE ROTARY FLUID ACTUATOR HAVING A SHAFT COMPRISING IN COMBINATION: (A) A STATIONARY HOUSING HAVING FLUID INLET AND RETURN PORTS; (B) A FOLLOW-UP VALVE MEMBER ROTATABLY SUPPORTED IN SAID HOUSING AND SAID MEMBER HAVING MEANS ADAPTED TO BE DRIVABLY DETACHABLY COUPLED TO THE SHAFT OF THE ACTUATOR, SAID MEMBER HAVING CIRCULAR PORTS RESPECTIVELY CONNECTED BY BORES TO SAID HOUSING PORTS, AND OTHER PORTS RESPECTIVELY DETACHABLY CONNECTABLE BY OTHER BORES IN SAID COUPLING MEANS OF SAID MEMBER WITH FLUID PASSAGES IN THE ACTUATOR; (C) A CONTROL VALVE MEMBER ROTATABLY SUPPORTED IN SAID HOUSING CONCENTRICALLY WITH SAID FOLLOW-UP MEMBER AND HAVING A SEALING FACE IN SEALING RELATION TO SAID FOLLOW-UP MEMBER ADJACENT TO SAID PORTS THEREOF, SAID CONTROL VALVE MEMBER HAVING A PORTION ACCESSIBLE FROM OUTSIDE SAID HOUSING THROUGH WHICH A CONTROL TORQUE MAY BE APPLIED; (D) CIRCULAR PLUGS DISPOSED IN SAID CONTROL VALVE MEMBER FLUSH WITH SAID SEALING FACE AND CONCENTRIC WITH SAID CIRCULAR PORTS, AND OPERATIVE TO EFFECTIVELY CLOSE THEM, AND HENCE SAID VALVE, WHEN SAID VALVE MEMBERS ARE IN A NEUTRAL POSITION; AND (E) GROOVE-DEFINING MEANS IN SAID SEALING FACE OF SAID CONTROL MEMBER AND INTERCONNECTING ADJACENT PAIRS OF SAID CIRCULAR PLUGS, SAID GROOVE MEANS BEING OPERATIVE TO INTERCONNECT ONE OF SAID CIRCULAR PORTS WITH ONE OF SAID OTHER PORTS WHEN SAID PLUGS ARE DISPLACED FROM SAID CIRCULAR PORTS.