Pressure fluid control and unloader therefor

Claim 1

AN UNLOADER COMPRISING: (A) A HOUSING HAVING AN INLET ADAPTED TO RECEIVE PRESSURE FLUID, AN OUTLET FOR DISCHARGING PRESSURE FLUID RECEIVED BY THE INLET, AND AN EXHAUST PORT FOR PRESSURE EXHAUSTING FLUID WHEN THE PRESSURE THEREOF EXCEEDS A PREDETERMINED MAXIMUM; (B) A VALVE SEAT DISPOSED IN THE HOUSING BETWEEN THE INLET AND THE EXHAUST PORT; (C) A VALVE MEMBER SLIDABLY DISPOSED IN THE HOUSING ENGAGING THE SEAT TO BLOCK FLOW OF PRESSURE FLUID FROM THE INLET TO THE EXHAUST PORT WHICH URGES THE VALVE MEMBER AWAY FROM THE SEAT; (D) THE HOUSING DEFINING A PRESSURE CHAMBER ON THE SIDE OF THE VALVE MEMBER OPPOSITE FROM THE INLET HAVING A PORT ADAPTED TO RECEIVE CONTROLLED PRESSURE FLUID WHICH BIASES THE VALVE MEMBER ONTO THE SEAT UNTIL THE PRESSURE OF FLUID RECEIVED AT THE INLET EXCEEDS A PREDETERMINED MAXIMUM; (E) THE VALVE MEMBER HAVING PASSAGE MEANS PROVIDING COMMUNICATION FROM THE INLET TO THE OUTLET WHEN THE VALVE MEMBER ENGAGES THE SEAT; (F) THE PASSAGE MEANS PROGRESSIVELY RESTRICTING THE COMMUNICATION FROM THE INLET TO THE OUTLET AND PROVIDING PROGRESSIVELY INCREASING COMMUNICATION FROM THE INLET TO THE EXHAUST PORT AS THE VALVE MEMBER PROGRESSIVELY MOVES AWAY FROM THE SEAT; AND (G) MUFFLER MEANS CONNECTED TO SAID HOUSING FOR ABATING THE NOISE CAUSED BY FLOW OF PRESSURE FLUID; (H) SAID MUFFLER MEANS COMPRISING A PAIR OF CONCENTRIC RING MEMBERS DISPOSED IN SAID HOUSING ON THE SIDE OF SAID VALVE MEMBER OPPOSITE FROM THE INLET; (I) ONE OF SAID RING MEMBERS BEING ALONG A PATH OF FLOW OF EXHAUSTING PRESSURE FLUID AND THE OTHER OF SAID RING MEMBERS BEING ALONG THE PATH OF FLOW TO THE OUTLET.