Hydraulic cushion for dies

Claim 1

IN A PRESS HAVING A RAM, A DIE, A HYDRAULIC CUSHION FOR SAID DIE INCLUDING AT LEAST ONE HYDRAULIC CYLINDER PROVIDED WITH A RECIPROCATING PISTON THEREIN ARRANGED TO REACT ON SAID DIE SO AS TO BIAS IT TO ITS EXTENDED POSITION; A TANK OF HYDRAULIC FLUID UNDER REGULATED RELATIVELY LOW PRESSURE, A HYDRAULIC FLUID CONNECTION BETWEEN SAID TANK AND SAID CYLIDER WHEREBY HYDRAULIC FLUID UNDER TANK PRESSURE IS SUPPLIED FROM SAID TANK TO SAID CYLINDER AND PISTON FOR BIASING SAID DIE TO ITS EXTENDED POSITION BUT RETURN FLOW THROUGH SUCH CONNECTION IS PREVENTED, A SECOND HYDRAULIC FLUID CONNECTION BETWEEN SAID TANK AND CYLINDER HAVING NORMALLY CLOSED PRESSURE RELIEF VALVE MEANS THEREIN INCLUDING A PILOT VALVE AND OTHER VALVE MEANS ADAPTED TO PROVIDE A BYPASS IN THE SECOND FLUID CONNECTION AROUND THE PILOT VALVE ON OPENING OF THE OTHER VALVE MEANS WHEREBY A PREDETERMINED RESISTANCE TO DISPLACEMENT OF HYDRAULIC FLUID FROM THE CYLINDER IS PROVIDED SO AS TO FORM A HYDRAULIC CUSHION FOR SAID DIE UPON CLOSING OF THE PRESS RAM, AND MEANS TO REDUCE THE BACK PRESSURE IN SAID SECOND FLUID CONNECTION ON THE CYLINDER SIDE OF SAID PRESSURE RELIEF VALVE MEANS DUE TO RESISTANCE TO OPENING MOVEMENT OF SAID PRESSURE RELIEF VALVE MEANS PRIOR TO THE OPENING OF SAID PRESSURE RELIEF VALVE MEANS INCLUDING AN ACCUMULATOR CHAMBER CYLINDER HAVING A PORTION AT ONE END IN COMMUNICATION WITHSAID PRESSURE RELIEF VALVE MEANS OF SUB-