Manually actuated positioning control system

Claim 1

A POSITION CONTROL SYSTEM COMPRISING A REVERSIBLE HYDRUALIC ACTUATOR HAVING A PAIR OF CONTROL PORTS, A SOURCE OF FLUID UNDER PRESSURE COMPRISING A REVERSIBLE PUMP HAVING TWO FLUID PORTS, A DISTRIBUTOR VALVE INTERPOSED BETWEEN SAID CONTROL PORTS OF SAID ACUATOR AND SAID SOURCE OF FLUID UNDER PRESSURE, SAID DISTRIBUTOR VALVE COMPRISING A CASING HAVING A BORE THERETHROUGH, A VALVE MEMBER SLIDABLY MOUNTED IN SAID BORE, SAID VALVE MEMBER COMPRISING A SUSBTANTIALLY CYLINDRICAL SPOOL HAVING A SUBSTANTIALLY CENTRAL ANNULAR GROOVE DEFINING TWO END PORTIONS, EACH END PORTION HAVING A REDUCED DIAMETER ANNULAR PORTION AT EACH OF ITS ENDS DEFINING A CENTRAL RIB THEREBETWEEN, EACH OF SAID REDUCED DIAMETER PORTIONS DEFINING A CAPILLARY PASSAGE, SAID DISTRIBUTOR CASING HAVING TWO PAIRS OF LONGITUDINALLY POSITIONED CONTROL PORTS, SAID REDUCED DIAMETER PORTIONS ON EACH END PORTION OF SAID SPOOL BEING ALIGNED WITH THE RESPECTIVE PAIRS OF CONTROL PORTS WHEN THE VALVE MEMBER IS IN NEUTRAL POSITION TO CLOSE SAID PORTS, MEANS NORMALLY RETAINING SAID VALVE MEMBER IN NEUTRAL POSITION TO CUT OFF FLOW OF FLUID INTO AND OUT OF THE CONTROL PORTS OF SAID VALVE MEMBER, SAID CASING HAVING A PAIR OF CONTROL CHAMBERS OPERATIVELY CONNECTED RESPECTIVELY TO THE FLUID PORTS OF SAID PUMP AND IN COMMUNICATION WITH OPPOSED ENDS OF SAID VALVE MEMBER TO EFFECT MOVEMENT OF THE LATTER WHEN THE PRESSURE IN ONE OF SAID CHAMBERS EXCEEDS A PREDETERMINED AMOUNT, MEANS CON-