Patent ID: 6971725

Claim:
A hydraulic valve for controlling an emergency brake on a vehicle, the hydraulic valve comprising: a body having a main bore into which a first passage, a second passage, and a third passage open; a first poppet slidably received in the main bore and defining a first chamber and a second chamber on opposite sides of the first poppet, wherein the first passage communicates with the first chamber; a passageway providing a fluid path between the first and second chambers and having a dampening orifice; a first valve seat having a seat aperture there through that extends between the first chamber and a third chamber in the bore, wherein the second passage communicates with the third chamber; a first spring biasing the first poppet against the first valve seat; a second poppet slidably received in the main bore on an opposite side of the first valve seat from the first poppet, and having a portion projecting into the seat aperture and engaging the first poppet; a sensing piston slidably received in the main bore, and including a piston aperture with a first end communicating with the third chamber and with a second end communicating with the third passage, and a second valve seat formed at the first end of the piston aperture and being selectively engaged by the second poppet; and an actuator operably coupled to transfer force to the sensing piston and thereby operate the hydraulic valve.