Valve actuating mechanism

Claim 1

A VALVE ACTUATING MECHANISM COMPRISING A RECIPROCABLE VALVE ACTUATING MEMBER; MEANS DEFINING DIFFERENTIAL AREA CHAMBERS WITH SAID MEMBER HAVING RESTRICTED COMMUNICATION WITH EACH OTHER; A CONTROL VALVE OPERATIVE SELECTIVELY TO ADMIT EXPANSIBLE FLUID UNDER PRESSURE INTO LARGER ONE OF SUCH CHASMBERS TO MOVE SAID MEMBER IN ONE DIRECTION AND TO HOLD SAID MEMBER THEREAT DESPITE BUILDUP OF PRESSURE IN THE SMALLER CHAMBER THROUGH SUCH RESTRICTED COMMUNICATION, AND TO VENT SAID LARGER CHAMBER WHEREBY EXPANSION OF THE FLUID IN THE SMALLER CHAMBER MOVES SAID MEMBER IN THE OPPOSITE DIRECTION; SAID MEANS COMPRISING A CYLINDER; SAID MEMBER COMPRISING A PACKLESS PISTON IN WHICH RADIAL CLEARANCE THEREOF WITH SAID CYLINDER PROVIDES SUCH RESTRICTED COMMUNICATION; AND A DIFFERENTIAL FLOW CONTROL DEVICE DISPOSED TO VENT FLUID UNDER PRESSURE FROM SAID LARGER CHAMBER AT A FASTER RATE THAN WHEN SAID CONTROL VALVE IS OPERATED TO ADMIT FLUID UNDER PRESSURE THEREINTO, SAID DEVICE COMPRISING AN ORIFICE CHECK VALVE WHICH IS CLOSED, EXCEPT FOR THE ORIFICE, WHEN FLUID UNDER PRESSURE IS ADMITTED INTO SAID LARGER CHAMBER AND WHICH IS OPENED FOR RAPID VENTING OF SAID LARGER CHAMBER.