Balanced regulating valve

Claim 1

A REGULATING VALVE OF THE TYPE DESCRIBED COMPRISING A HOUSING FORMED WITH A VALVE COMPARTMENT, A VALVE SEAT IN SAID COMPARTMENT, AN INLET PORT COMMUNICATING WITH SAID COMPARTMENT ABOVE SAID VALVE SEAT, AN OUTLET PORT ARRANGED BELOW SAID VALVE SEAT, A POPPET VALVE POSITIONED IN SAID COMPARTMENT ABOVE SAID SEAT, A COMPRESSION SPRING URGING SAID VALVE AGAINST SAID SEAT, SAID VALVE HAVING AN UPWARDLY EXTENDING STEM SLIDABLE IN A SLEEVE FIXEDLY MOUNTED IN SAID BODY ABOVE SAID COMPARTMENT, SAID SLEEVE BEING FORMED WITH A COUNTERBORE IN ITS UPPER PORTION TO PROVIDE AN ANNULAR SHOULDER ENCIRCLING THE UPPER PORTION OF SAID STEM IN SPACED RELATION THERETO, AN ANNULAR SEAL POSITIONED ON SAID SHOULDER AND BEING FORMED WITH AN INNER DOWNWARDLY EXTENDING CYLINDRICAL PORTION ENCIRCLING SAID STEM AND POSITIONED BETWEEN SAID SHOULDER AND THE STEM, SAID SEAL HAVING AN OUTER UPWARDLY EXTENDING CYLINDRICAL PORTION POSITIONED AGAINST SAID COUNTERBORE, A BUSHING MOUNTED IN SAID COUNTERBORE, AND MEANS URGING SAID BUSHING DOWNWARDLY TO CLAMP SAID SEAL AGAINST SAID SHOULDER, SAID VALVE BEING FORMED WITH A PASSAGE EXTENDING AXIALLY UPWARDLY FROM BELOW THE AREA OF THE VALVE CONTACTING SAID SEAT AND COMMUNICATING WITH THE AREA ABOVE THE UPPER END OF SAID STEM FOR THE TRANSMISSION OF FLUID THERETO FROM THE AREA BELOW SAID SEAT, SAID HOUSING BEING FORMED WITH A CYLINDER BELOW SAID VALVE CHAMBER, A PISTON MOUNTED IN SAID CYLINDER, MEANS FOR APPLYING FLUID UNDER PREDETERMINED CONSTANT PRESSURE AGAINST THE UNDER SIDE OF SAID PISTON TO URGE THE SAME UPWARDLY, SAID VALVE ALSO HAVING A DOWNWARDLY EXTENDING STEM FOR ENGAGEMENT BY SAID PISTON WHEN THE SAME IS MOVED UPWARDLY TO MOVE SAID VALVE FROM THE SEAT, A CONDUIT EXTENDING FROM SAID OUTLET PORT TO THE AREA ABOVE SAID PISTON FOR THE CONVEYANCE OF FLUID THEREAGAINST TO URGE SAID PISTON DOWNWARDLY AGAINST SAID PREDETERMINED CONSTANT PRESSURE.