Brake cylinder release valves

Claim 1

IN A BRAKE CYLINDER RELEASE VALVE, A CASING HAVING A CONNECTION WITH A BRAKE CONTROL VALVE AND A CONNECTION WITH A BRAKE CYLINDER, A VALVE STEM IN SAID CASING HAVING A DOUBLE ACTING VALVE MEMBER ON ONE END AND A PISTON SLIDABLE IN SAID CASING ON THE OTHER END, A VALVE SEAT IN SAID CASING OPENED BY SAID VALVE MEMBER TO PERMIT FREE PASSAGE OF AIR PRESSURE FROM SAID BRAKE CONTROL VALVE TO SAID BRAKE CYLINDER, A SPRING ON SAID VALVE STEM BIASING SAID VALVE MEMBER IN SAID OPEN POSITION, MANUAL OPERATED MEANS IN SAID CASING FOR ACTUATING SAID VALVE STEM TO MOVE SAID VALVE MEMBER TO CLOSE ON SAID VALVE SEAT AND DISCONNECT THE AIR PRESSURE FROM SAID BRAKE CYLINDER WHILE RETAINING THE AIR PRESSUE FROM SAID BRAKE CONTROL VALVE, SAID RETAINED AIR PRESSURE BEING EFFECTIVE ON ONE SIDE OF SAID PISTON OPPOSED TO SAID SPRING TO HOLD SAID ALVE STEM AND VALVE MEMBER IN ACTUATED POSITION AFTER SAID MANUAL OPERATING MEANS IS RELEASED, AND AIR PASSAGE MEANS IN SAID VALVE STEM EXTENDING FROM SAID BRAKE CONTROL PASSAGE BELOW SAID PISTON TO AN EXHAUST POSITION ABOVE SAID PISTON, SAID AIR PASSAGE MEANS CONTROLLED BY SAID PISTON INDEPENDENTLY OF THE MOVEMENT OF SAID VALVE STEM FOR CONTROLLING THE PASSAGE OF AIR THERETHROUGH DEPENDING UPON THE PRESSSURE THEREOF.