Shock modulating device for a hydraulically driven gas compressor

Claim 1

IN A HYDRAULICALLY OPERATED SYSTEM FOR PUMPING COMPRESSIBLE FLUIDS, HYDRAULICALLY DRIVEN PUMP INCLUDING A RECIPCROCATORY PISTON HAVING HYDRAULICALLY ACUTATED OPPOSED PISTON FACES, AND A DRIVEN FLUID COMPRESSING PISTON FACE, A SOURCE OF HYDRAULIC PRESSURE MEDIUM, A SUPPLY LINE FOR SUPPLYING SAID HYDRAULIC MEDIUM UNDER PRESSURE FROM SAID SOURCE TO SAID HYDRAULICALLY ACTUATED FACES INCLUDING A THROTTLE VALVE IN SAID LINE PROVIDING DIFFERENTIAL UPSTREAM AND DOWNSTREAM PRESSURES AT OPPOSITE SIDES OF SAID THROTTLE VALVE, A REVERSING VALVE IN SAID SUPPLY LINE BETWEEN SAID THROTLE VALVE AND PUMP HAVING HYDRAULIC FLUID SUPPLY AND EXHAUST CONNECTIONS TO SAID HYDRAULICALLY ACTUATED FACES, EXHAUST CONNECTIONS FROM SAID REVERSING VALVE INCLUDING A FLOW SHUT-OFF VALVE HAVING A VALVE ELEMENT SHIFTABLE BETWEEN EXHAUST OPEN AND SHUT-OFF POSITIONS, A COMPENSATING VALVE PROVIDING A CONNECTION FROM THE UPSTREAM SIDE OF SAID THROTTLLE VALVE TO EXHAUST, AND HAVING A VALVE ELEMENT SHIFTABLE BETWEEN EXHAUST SHUT-OFF AND OPEN POSITIONS, AND UPSTREAM AND DOWNSTREAM CONNECTIONS RESPONSIVE TO AN INCREASE UPSTREAM, DOWNSTREAM PRESSURE DIFFERENTIAL TO MOVE SAID COMPENSATING VALVE ELEMENT TO OPEN POSITION TO DISCHARGE SAID UPSTREAM PRESSURE TO EXHAUST, SAID FLOW SHUT-OFF VALVE HAVING CONNECTIONS CHANNELLING PRESSURE FROM THE UPSTREAM AND DOWNSTREAM SIDES OF SAID THROTTLE VALVE AGAINST SAID FLOW SHUT-OFF VALVE ELEMENT RESPONSIVE TO A SAID INCREASED UPSTREAM, DOWNSTREAM DIFFERNETIAL TO MOVE SAID FLOW SHUT-OFF VALVE ELEMENT TO THE SHUT-OFF POSITION.