Patent ID: 7784488

Claim:
In a hydraulic system having a plurality of hydraulic functions divided into a primary section and a secondary section with a primary supply line connected to the hydraulic functions in the primary section and a secondary supply line connected to the hydraulic functions in the secondary section, a priority valve comprising: an inlet port connected to the primary supply line; an outlet port connected to the secondary supply line; a valve seat through which fluid flows between the inlet port and the outlet port; a poppet having a first side and a second side that selectively engages the valve seat in response to pressure acting on the first side, a first passageway for fluid to flow between the inlet port and the first side, a second passageway for fluid to flow between the outlet port and the first side; and a passive control spool selectively opening and closing the first passageway and the second passageway in response to pressure at the inlet port acting on the passive control spool; and a spring that applies force to a first end section of the passive control spool to bias the passive control spool into a first position which opens the first passageway and closes the second passageway, wherein when a force exerted on the passive control spool by pressure at the inlet port is greater than a force from the spring, the passive control spool moves into a second position which closes the first passageway and opens the second passageway.