Dual capacity fluid pressure operated clutch servo

Claim 1

A FLUID PRESSURE OPERATED FRICTION CLUTCH COMPRISING A ROTARY ANNULAR CLUTCH CYLINDER, MEANS FOR DIVIDING SAID ANNULAR CYLINDER INTO A RADIALLY OUTWARD PORTION AND A RADIALLY INWARD PORTION, AN ANNULAR PISTON HAVING FIRST AND SECOND STEPPED DIAMETER PORTIONS SITUATED RESPECTIVELY IN SAID RADIALLY INWARD AND RADIALLY OUTWARD CYLINDER PORTIONS, EACH CYLINDER PORTION AND ITS COOPERATING PISTON PORTION DEFINING A SEPARATE PRESSURE CAVITY, FIRST CLUTCH DISCS CARRIED BY SAID CYLINDER PORTION, OTHER CLUTCH DISCS CARRIED BY ANOTHER TORQUE DELIVERY ELEMENT OF SAID CLUTCH IN REGISTRY WITH SAID FIRST CLUTCH DISCS, SAID PISTON ENGAGING SAID DISCS TO ESTABLISH FRICTIONAL DRIVING RELATIONSHIP BETWEEN SAID CYLINDER PORTION AND SAID OTHER ELEMENT, A VALVE CHAMBER IN FLUID COMMUNICATION WITH THE RADIALLY INWARD PRESSURE CAVITY, A VALVE ELEMENT IN SAID VALVE CHAMBER ADAPTED TO MOVE THEREIN FROM ONE AXIAL POSITION TO ANOTHER, A VALVE ORIFICE ESZTABLISHING COMMUNICATION BETWEEN THE RADIALLY INWARD CAVITY AND ONE END OF SAID VALVE CHAMBER, A FLUID PRESSURE DISTRIBUTOR PASSAGE ESTABLISHING COMMUNICATION BETWEEN THE RADIALLY OUTWARD CAVITY AND SAID ONE END OF SAID VALVE CHAMBER, MEANS FOR APPLYING A VALVE ACTUATING FORCE TO SAID VALVE ELEMENT URGE IT INTO REGISTRY WITH SAID VALVE ORIFICE AND INTERRUPTING COMMUNICATION BETWEEN SAID PRESSURE CHAMBERS, AND MEANS FOR CHANGING THE VALVE ACTUATING FORCE TO APPROPRIATELY CHANGE THE CLUTCH TORGUE CAPACITY, THE MAGNITUDE OF THE VALVE ACTUATING FORCE ACTING UPON SAID VALVE ELEMENT TO URGE IT TO AN ORIFICE CLOSING POSITION BEING REDUCED WHEN SAID RADIALLY OUTWARD CAVITY AND SAID RADIALLY INWARD CAVITY ARE IN FLUID COMMUNICATION.