| 摘要 |
A safety valve cap providing an elongated inner chamber with an internally screw-threaded open lower end for threaded engagement on the extended end of a conventional valve stem associated with a vehicle tire, for example. A check valve is movably positioned in the inner chamber between a compression spring and a depressor plate. When the safety valve cap is threaded onto the valve stem, the depressor plate actuates the valve stem check valve releasing compressed air into a first portion of the inner chamber until the air pressure therein is balanced with the tire pressure. A subsequent increase in the tire pressure will move the body portion of the movable check valve outwardly against the forces of the compression spring, actuating said check valve and releasing the excess pressure through a second chamber portion and an orifice in the end wall of the cap to the atmosphere until the air pressure in the tire is slightly overbalanced by the forces of the compression spring, whereupon the body portion of the check valve will move inwardly stopping the flow of compressed air.
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