Pressure cap for sealed cooling system

Claim 1

IN COMBINATION, A CLOSURE CAP STRUCTURE AND AN INTERNAL COMBUSTION ENGINE RADIATOR HAVING A TUBULAR FILLING NECK WITH THE CLOSURE CAP STRUCTURE THEREON, SAID CAP STRUCTURE INCLUDING A GENERALLY CUP-SHAPED CAP ITSELF HAVING A FLUID NIPPLE EXTENDING OUTWARDLY FROM ITS SIDE WALL IN OVERLYING SPACED RELATION ABOVE SAID NECK, A VENTED SURGE TANK CONNECTED WITH SAID FLUID NIPPLE HAVING FLUID OVERLYING THE RADIATOR, AN ANNULAR CUP SHOULDER AT AN OPEN END OF THE CUPSHAPED CAP, A SPRING DISPSOED INSIDE OF THE CUP DEFINED BY SAID CAP, A BACK-UP DIAPHRAGM RING ENGAGED ON ITS TOP SIDE WITH SAID SPRING AND HAVING A DIAPHRAGM GASKET ON ITS UNDERSIDE FOR MOVEMENT WITH SAID BACK-UP DIAPHRAGM RING INTO AND OUT OF ENGAGEMENT WITH THE TUBULAR FILLING NECK, A LOCK RING SECURED WITH THE SIDE WALL DEFINING THE OPEN END OF SAID CAP AXIALLY SPACED FROM SAID CAP SHOULDER WITH SAID BACK-UP RING AND SAID DIAPHRAGM GASKET BEING MOVABLE AXIALLY BETWEEN SAID DIAPHRAGM RING AND SAID CAP SHOULDER UPON THE DEVELOPMENT OF EXCESSIVE PRESSURE IN HE RADIATOR SUFFICIENT TO CAUSE UNSEATING OF SAID DIAPHRAGM GASKET FROM SAID FILLING NECK PERMITTING FLUID FLOW BETWEEN THE OUTER MARGIN OF SID BACK-UP DIAPHRAGM RING AND THE SIDE WALL OF THE CUP INTO THE CUP AND THEN THROUGH SAID FLUID NIPPLE INTO SAID SURGE TANK, SAID LOCK RING PROVIDING MEANS SECURING SAID DIAPHRAGM GASKET IN INTEGRAL ASSEMBLY WITH SAID CAP TO PERMIT THE CAP, SPRING, DIAPHRAGM RING AND DIAPHRAGM GAKSET TO BE ENGAGED ON AND REMOVED FROM AW FILLING NECK SEAT AS A UNIT, AN AUXILIARY VALVE MEMBER MOUNTED ON SAID BACK-UP DIAPHRAGM RING AND SAID DIAPHRAGM GASKET ADAPTED TO OPEN WHEN THE FLUID IN THE RADIATOR IS COOLING PERMITTING FLUID FLOW FROM THE SURGE TANK TO THE RADIATOR, AND MEANS ON SAID CUP-SHAPED CAP SECURING THE CAP IN SERALED ASSEMBLY WITH THE TUBULAR FILLING NECK OF SAID RADIATOR.