Shut-off valve and associated pressure relief means

Claim 1

IN COMBINATION, A SPOOL VALVE HAVING A BODY WITH A FIRST BORE HAVING AN INLET ADAPTED TO BE CONNECTED TO A HIGH PRESSURE SOURCE OF FLUID AND AN OUTLET ADAPTED TO COMMUNICATE WITH A FLUID OPERABLE DEVICE; AN INDEPENDENTLY OPERABLE SPOOL MEMBER IN SAID BORE HAVING A NEUTRAL POSITION AND CONSTRUCTED AND ARRANGED TO STOP FLOW THROUGH SAID INLET TO SAID OUTLET WHEN IN AID NEUTAL POSITION; A FLUID PRESSURE OPERATED SAFETY VALVE IN COMMUNICATION ON OPPOSITE SIDES THEREOF WITH SAID INLET AND A REGION OF LOW PRESSURE AND ADAPTED TO ESTABLISH COMMUNICATION BETWEEN SAID INLET AND REGION OF LOW PRESSURE WHEN PRESSURE IN SAID INLET EXCEEDS A PREDETERMINED AMOUNT; A SECOND BORE IN SAID BODY ADAPTED TO COMMUNICATE WITH SAID REGION OF LOW PRESSURE AND WITH SAID INLET; AND MEANS ASSOCIATED WITH SAID SECOND BORE TO CONTROL FLOW THROUGH SAID SECOND BORE; SAID MEANS COMPRISING, A FLUID PRESSURE OPERATED PRESSURE VALVE INCLUDING A PASSAGE CONNECTED AT ONE END TO SAID INLET AND AT THE OTHER END TO AN ENLARGED DIAMETER CHAMBER IN COMMUNICATION WITH SAID REGION OF LOW PRESSURE; A VALVE SEAT IN SAID CHAMBER ADJACENT SAID PASSAGE; A PISTON IN SAID CHAMBER HAVING A VALVE THEREIN ADAPTED TO COOPERATE WITH SAID VALVE SEAT, SAID PISTON BEING BIASED TO MOVE SIAD VALVE TO OPEN POSITION BY PRESSURE IN SAID INLET AND TO CLOSED POSITION BY PRESSURE AND SPRING MEANS IN SAID CHAMBER; A RESTRICTED PASSAGE THROUGH SAID PISTON AND VALVE ESTABLISHING COMMUNICTION BETWEEN SAID INLET AND SAID CHAMBER; MEANS ASSOCIATED WITH SAID SPOOL MEMBER ADAPTED TO SHUT OFF COMMUNICATION BETWEEN SAID AND SAID REGION OF LOW PRESSURE WHEN SAID SPOOL MEMBER IS MOVED FROM ITS NEUTRAL POSITION AND RENDERED INEFFECTIVE WHEN SAID SPOOL MEMBER IS IN ITS NEUTRAL POSITION; A THIRD BORE IN SAID BODY HAVING ONE END IN COMMUNICATION WITH SAID CHAMBER ADJACNET THE VALVE SEAT AND THE OTHER END IN COMMUNICATION WITH SAID REGION BY LOW PRESSURE; SAID VALVE BEING ADAPTED TO SHUT OFF FLOW OF FLUID FROM SAID INLET TO SAID THIRD BORE WHEN IT IS BIASED TO ITS SEAT.