Electrohydraulic actuator

Claim 1

AN ELECTROHYDRAULIC SERVO SYSTEM COMPRISING, IN COMBINATION, A SINGLE HYDRAULIC MOTOR HAVING A MECHANICAL OUTPUT MEMBER; THREE POSITION PICKOFF MEANS IN COMMON COOPERATION WITH SAID MOTOR FOR PROVIDING SIGNALS INDICATIVE OF THE DRIVEN POSITION OF SAID OUTPUT MEMBER RELATIVE TO SAID MOTOR; THREE SUMMING AMPLIFIERS, A FIRST INPUT TERMINAL OF EACH BEING COMMONLY CONTINOUSLY CONNECTED TO AN INPUT TERMINALS, A SECOND INPUT TERMINAL OF EACH BEING CONTINUOUSLY CONNECTED TO THE OUTPUT OF A MUTUALLY EXCLUSIVE ONE OF SAID POSITION PICKOFF MEANS; THREE LIKE PROPORTIONAL TYPE FLUID CONTROL VALVES, EACH CONTINUOUSLY RESPONSIVELY CONNECTED IN ELECTRICAL CIRCUIT TO THE OUTPUT OF A MUTUALLY EXCLUSIVE ONE OF SAID AMPLIFIERS; AND A MANIFOLD BLOCK MOUNTING SAID CONTROL VALVES AND COMMONLY CONNECTING CORREPONDING PORTS OF SAID CONTROL VALVES IN FLUID CIRCUIT FOR PROPORTIONAL CONTROL OF SAID HYDRAULIC MOTOR IN ACCORDANCE WITH THE COMBINED FLUID FLOW FROM SAID VALVES, SAID MANIFOLD BLOCK HAVING A TERMINAL FACE WHICH SEALINGLY ABUTS A MAIN HOUSING OF SAID MOTOR AND HAVING CAVITIES FOR SEALINGLY INSTALLING SAID VALVES IN A MUTUALLY-SPACED SIDE-BY-SIDE AND PARALLEL RELATIONSHIP, WITH CORRESPONDING PORTS OF SAID VALVES LYING IN A COMMON TRANSVERSE PLANE OF SAID MANIFOLD BLOCK; SAID BLOCK FURTHER HAVING AN ANNULAR GROOVE IN EACH CAVITY AT EACH OF SAID TRANSVERSE PLANES, AND PASSAGES THEREIN RADIALLY-EXTENDING FROM SAID GROOVES, THE PASSAGES IN A GIVEN TRANSVERSE PLANE TERMINATING AT AN INTERSECTION THEREOF AS A SET OF PASSAGES FOR ALLOWING FLUID COMMUNICATION BETWEEN SAID GROOVES OF SAID PLANE; SAID BLOCK FURTHER HAVING A LIKE NUMBER OF SPACED APART APERTURES LOCATED IN SAID TERMINALS FACE OF SAID BLOCK AND EXTENDING PERPENDICULAR TO SAID FACE, EACH APERTURE TERMINATING AT AN INTERSECTION WITH A MUTUALLY EXCLUSIVE ONE OF SAID SETS OF INTERSECTING PASSAGES.