Fluid pressure operated shut-off valve

Claim 1

A FLUID PRESSURE OPERATED SHUT-OFF VALVE FOR WELLS COMPRISING: A MAIN VALVE HOUSING; MEANS FOR SUPPORTING SAID HOUSING IN A FLUID FLOW LINE; SAID HOUSING HAVING THEREIN A FLUID PASSAGE FOR THE FLOW OF WELL FLUID THERETHROUGH AND A MAIN VALVE CHAMBER; A MAIN VALVE SHIFTABLY DISPOSED IN SAID CHAMBER FOR MOVEMENT INTO SAID FLUID PASSAGE TO CLOSE OFF THE FLOW OF WELL FLUID THERETHROUGH; A PASSAGEWAY LEADING FROM SAID FLUID PASSAGE TO THE MAIN VALVE CHAMBER AT THE OPPOSITE SIDE OF THE MAIN VALVE FROM SAID FLUID PASSAGE; AND PILOT VALVE MEANS INTERPOSED IN SAID PASSAGEWAY AND RESPONSIVE TO A CHANGE IN FLUID PRESSURE IN THE FLUID PASSAGE AFORESAID FOR OPENING SAID PASSAGEWAY TO PERMIT FLUID FROM SAID FLOW PASSAGE TO FLOW INTO THE VALVE CHAMBER AND SHIFT SAID MAIN VALVE TO A CLOSED POSITION; SAID HOUSING HAVING A BORE THEREIN COMMUNICATING WITH SAID CHAMBER; SAID PILOT VALVE MEANS INCLUDING A PILOT VALVE SUPPORT HAVING A PORTION PROVIDED WITH A VALVE SEAT AND EXTENDING INTO SAID BORE AND A PORTION PROJECTING FROM SAID HOUSING, A PILOT VALVE STEM CARRIED BY SAID LATTER PORTION; SAID PASSAGEWAY LEADING INTO SAID BORE THROUGH SAID SEAT; AND SAID STEM HAVING A HEAD ENGAGEABLE WITH SAID SEAT TO CLOSE SAID PASSAGEWAY.