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An electrohydraulic proportional valve wherein an electromagnetic force motor sends a mechanical signal to a pilot actuator which moves a main spool. The pilot actuator includes a pilot spool slidably received in a pilot sleeve. A feedback spool which is movable with the main spool has a camming sur

An electrohydraulic proportional valve wherein an electromagnetic force motor sends a mechanical signal to a pilot actuator which moves a main spool. The pilot actuator includes a pilot spool slidably received in a pilot sleeve. A feedback spool which is movable with the main spool has a camming surface against which the pilot sleeve rides. A load check valve is provided that isolates the load pressure from system pressure when desired.

대표청구항 ▼

A proportional control valve comprising: a valve housing having a main bore therethrough, means for forming opposite ends of said bore, a main spool, shorter in length than said bore slidably received in said bore, ends of said main spool respectively forms in combination with a corresponding end of

A proportional control valve comprising: a valve housing having a main bore therethrough, means for forming opposite ends of said bore, a main spool, shorter in length than said bore slidably received in said bore, ends of said main spool respectively forms in combination with a corresponding end of said bore first and second pressure chambers at opposing sides of said main spool, said main spool being the only spool having any end thereof extending into or constituting a part of either one of said first and second pressure chambers, said valve housing having a first passageway communicating said bore with a source, a second passageway communicating said bore with a load, and a third passagway communicating said bore with tank, a force motor, a pilot control means responsive to signals received from said force motor for applying fluid pressure to one of said pressure chambers and thus moving said main spool in a direction away from the pressure chamber receiving said pressure and towards the other pressure chamber, a load check valve in said second passageway having a first position preventing fluid from flowing from said load to said third passageway and a second position permitting such flow, and moving means responsive to movement of said main spool toward said first pressure chamber for moving said check valve from said first position to said second position.