Shut-off valve

Claim 1

A VALVE COMPRISING A VALVE BODY HAVING INLET AND OUTLET PASSAGES AND A CIRCULAR VALVE SEAT INTERMEDIATE SAID PASSAGES, A CYLINDRICAL CHAMBER IN THE VALVE BODY COAXIAL WITH AND SPACED FROM THE VALVE SEAT ON THE UPSTREAM SIDE THEREOF, A VALVE PISTON HAVING HEAD AND SKIRT PORTIONS, THE SHIRT PORTION BEING SLIDEABLY DISPOSED WITHIN SAID CHAMBER, THE HEAD PORTION OF THE PISTON HAVING A SEATING SURFACE WHICH ENGAGES THE CIRCULAR SEAT IN THE VALVE BODY WHEN THE PISTON IS IN CLOSED POSITION, THE HEAD PORTION OF THE PISTON HAVING A PILOT PASSAGE THERETHROUGH AND A VALVE SEAT AT THE INNER END OF THE PILOT PASSAGE, ACTUATING MEANS FOR THE PISTON COMPRISING A STEM TO WHICH THE PISTON IS CONNECTED FOR LIMITED RELATIVE SLIDING MOVEMENT, SAID STEM EXTENDING THROUGH THE VALVE BODY TO THE EXTERIOR THEREOF, MEANS OUTWARDLY OF THE BODY FOR RECIPORCATING THE STEM WITHIN THE BODY IN NON-ROTATING RELATION THERETO, THE SKIRT PORTION OF THE PISTON HAVING A CENTRAL SUPPORT PORTION THROUGH WHICH THE STEM PASSES IN SLIDING RELATION, A PILOT VALVE AT THE END OF THE STEM WITHIN THE PISTON IN RIGID NONROTATING RELATION TO SAID STEM, SAID PILOT VALVE ENGAGING THE PILOT VALVE SEAT TO CLOSE THE PILOT PASSAGE WHEN THE STEM IS DISPLACED TO THE LIMIT OF ITS MOVEMENT RELATIVE TO THE PISTON IN THE DIRECTION OF THE PISTON HEAD, A COLLAR RIGIDLY CONNECTED TO THE STEM BETWEEN THE HEAD OF THE PISTON AND THE SUPPORT WITHIN THE PISTON SKIRT, A COMPRESSION SPRING INTERMEDIATE THE COLLAR ON THE STEM AND THE HEAD END OF THE PISTON URGING THE PISTON ALONG THE STEM IN A DIRECTION TOWARD THE VALVE SEAT IN THE BODY, AND GUIDE MEANS WITHIN THE HEAD PORTION OF THE PISTON SPACED AROUND THE PILOT VALVE SEAT THEREIN, SAID MEANS BEING SLIDEABLY ENGAGED BY THE VALVE STEM ADJACENT ITS PILOT VALVE PORTION.