Pressure-regulating valve

Claim 1

A hydraulic system comprising a pump, a reservoir, and a pressure regulator connecting said pump and said reservoir to a load, said pressure regulator comprising: a housing provided with a bore; a manually controlled input member slidable in said bore and actuatable from a starting position to control the pressure at said load; a valve member slidable in said bore and defining a controllable passage therein; means connecting said passage in a hydraulic network with said pump, said reservoir and said load; first spring means interposed between said members and having a force/displacement characteristic increasing with displacement at a rate greater for a larger displacement of said input member than for a smaller displacement of said input member from the starting position of the latter, said first spring means comprising at least two parallel springs rendered successively effective between said members upon displacement of said input member, said parallel springs including inner and outer coaxial springs, the outer spring being prestressed and bridging said members in all positions thereof, the inner spring being shorter than said outer spring and forming a lostmotion coupling with at least one of said members; and second spring means in said bore biasing said valve member toward said input member, said valve member being constructed and arranged for biasing against said first spring means by the fluid pressure at said load, said input member including: a spring seat slidably mounted in said bore, said outer spring bearing upon the said seat, a shoulder carried by said input member and axially entrained with said seat in the direction of said valve member for engagement with said inner spring, and a pin connected to said spring seat and to said shoulder and extending outwardly of said housing; a control plate swivelably mounted on said housing and engageable with said pin while being provided with a control lever; and a spring received in said bore and bearing at an end upon said housing and at the other end against said spring seat, said means for connecting said passage in said hydraulic network including a first fitting connecting said bore on the side of the valve member opposite said input member with said load, said passage including a channel in said valve member opening into said side of said bore and a circumferential groove formed in the periphery of said valve member and communicating with said channel, an inlet port communicating with said bore and formed in said housing while being connected to said pump, and an outlet port formed in said housing and opening into said bore while being connected with said reservoir, said groove selectively communicating with said ports upon axial displacement thereof.