Torque-limiting drive

Claim 1

IN COMBINATION: DRIVING MEANS; ROTARY DRIVEN MEANS; CLUTCH MEANS FLUID-PRESSURIZIBLE TO ENGAGE CONDITION TO INTERCONNECT AND DEPRESSURIZIBLE TO DISCONNECT SAID TWO MEANS; FLUID PRESSURE MEANS INCLUDING AN INLET ADAPTED FOR CONNECTION TO A FLUID PRESSURE SOURCE, A SUPPLY LINE TO THE CLUTCH MEANS, AN EXHAUST PORT AND A FIRST VALVE MOVABLE BETWEEN A FIRST POSITION CONNECTING THE SUPPLY LINE EXCLUSIVELY TO THE INLET AND A SECOND POSITION CONNECTING THE SUPPLY LINE TO BOTH THE INLET AND THE EXHAUST PORT; TORQUE-RESPONSIVE MEANS INCLUDING A CONTROL LINE TO RESERVOIR AND A SECOND VALVE CLOSING SAID CONTROL LINE AT OR BELOW PREDETERMINED TORQUE VALUES AND OPENING SAID CONTROL LINE AT EXCESS TORQUE VALUES; AND VALUE REGULATING MEANS INCLUDING PRESSURE-RECEIVABLE PORTIONS ACTING ON THE FIRST VALVE TO HOLD SAID FIRST VALVE IN ITS FIRST POSITION WHEN THE SECOND VALVE CLOSES THE CONTROL LINE AND TO CAUSE SAID FIRST VALVE TO SHIFT TO ITS SECOND POSITION WHEN THE SECOND VALVE OPENS SAID CONTROL LINE, SAID VALVE REGULATING MEANS CAUSING SAID FIRST VALVE TO REMAIN IN ITS SECOND POSITION UNDER INFLUENCE OF INLET PRESSURE EVEN THROUGH SAID SECOND VALVE RETURNS TO ITS CLOSED POSITION, AND SAID VALVE REGULATING MEANS INCLUDING MEANS FOR MOVING SAID FIRST VALVE TO ITS FIRST POSITION UPON DIUSCONNECTION OF SAID INLET FROM THE FLUID PRESSURE SOURCE.