Abstract: A pressure relief valve and regulator in which the valve chamber has a side port for connecting to the pressure line to be monitored. The valve seat opens to an exhaust and has a diameter slightly larger than the chamber diameter. The valve incorporates a double ended piston, spring, and cam whereby the cam offsets the normal compression gradient of the spring by rotating as the piston moves in and out.

Abstract: A regulator-unloader for fluid systems comprising, in a housing; an inlet passageway; an outlet passageway connected to said inlet passageway; a piston movable within said outlet passageway; an outlet valve connected to said inlet passageway and to said outlet passageway outwardly of said piston; a bypass passageway connected to said inlet passageway; a main bypass valve spaced within said bypass passageway; and a rod spaced within said inlet passageway and connected at one end to said piston and at the other end to said bypass valve; said rod being pivotally mounted in the housing at a point intermediate its ends.

Abstract: An unloader for a high pressure hydraulic system, as a high pressure spraying system, has a pressure inlet for connection with a pump, a pressure outlet for connection with a load and a bypass outlet with a bypass valve. A piston moves the bypass valve between open and closed positions. The flow of liquid through the unloader from the inlet to the pressure outlet and to the hydraulic load establishes a pressure differential across the piston to close the bypass valve. When no flow to the load occurs, there is no differential pressure across the piston and the bypass valve is opened.