Friction clutch control

Claim 1

IN A CLUTCH AND CLUTCH CONTROL ASSEMBLY, A FRICTION CLUTCH HAVING SPRING MEANS NORMALLY URGING IT INTO ENGAGED CONDITION AND AT LEAST ONE MOVABLE CLUTCH RELEASE LEVER BIASED IN ONE DIRECTION BY SAID SPRING MEANS, A FLUID PRESSURE MOTOR FOR ACTUATING SAID CLUTCH HAVING AN ELEMENT ADAPTED TO BE DISPLACED UNDER FLUID PRESSURE TO MOVE SAID LEVER AGAINST THE FORCE OF SAID SPRING MEANS TO DISENGAGE THE CLUTCH, A FLUID PRESSURE SYSTEM FOR OPERATING SAID MOTOR COMPRISING A SOURCE OF PRESSURE AND CONDUIT MEANS CONTAINING A METERING VALVE ASSEMBLY COMPRISING AN INLET PORT AND A VALVE ELEMENT NORMALLY BIASED TO CLOSE SAID PORT TO PREVENT TRANSMISSION OF FLUID PRESSURE TO SAID MOTOR, PISTON MEANS FOR OPERATING SAID VALVE ELEMENT AND HAVING ONE SIDE EXPOSED TO FLUID PRESSURE ENTERING SAID INLET PORT, A MANUALLY OPERATED CONTROL MEMBER FOR SAID VALVE ASSEMBLY, AND RESILIENT MEANS OPERATIVELY CONNECTING SAID MEMBER AND THE OTHER SIDE OF SAID PISTON MEANS, WHEREBY WHEN SAID MANUAL CONTROL MEMBER IS OPERATED TO DISENGAGE THE CLUTCH, SAID PISTON MEANS IS DISPLACED SUBJECT TO THE OPPOSED CONTROL FORCES OF SAID RESILIENT MEANS AND SAID FLUID PRESSURE ENTERING THE VALVE ASSEMBLY, AND WHEN SAID MANUAL CONTROL MEMBER IS RELEASED ENGAGEMENT OF SAID CLUTCH BY SAID SPRING MEANS IS EFFECTIVELY CONTROLLED BY SAID PISTON MEANS OF THE METERING VALVE ASSEMBLY, SAID METERING VALVE ASSEMBLY COMPRISING A CYLINDER SLIDABLY MOUNTING SAID PISTON MEANS AND DEFINING AN INLET CHAMBER AT SAID ONE SIDE THEREOF, SAID INLET PORT BEING PROVIDED BETWEEN THE SOURCE OF PRESSURE AND SAID INLET CHAMBER AND SAID CONDUIT MEANS CONNECTING SAID INLET CHAMBER DIRECTLY TO SAID FLUID MOTOR, MEANS DEFINING AN EXHAUST PORT FOR SAID CHAMBER AND MEANS FOR CLOSING SAID EXHAUST PORT WHEN SAID INLET PORT IS OPENED AND WHEN SAID MANUAL CONTROL MEMBER IS OPERATED TO DISENGAGE THE CLUTCH, AND MEANS FOR APPLYING FLUID PRESSURE ENTERING SAID INLET PORT TO OPPOSE THE FORCE EXERTED BY SAID RESILIENT MEANS ON SAID PISTON MEANS SEPARATELY OF THE FLUID PRESSURE ACTING ON SAID PISTON MEANS IN SAID INLET CHAMBER.