Load sensing steering system

Claim 1

A hydraulic steering circuit for an industrial vehicle comprising: a supply of fluid within a reservoir; passage means connecting the reservoir to a first variable displacement pump, the pump having a displacement control; a hydraulic steering motor operatively connected to the pump and to a ground engaging wheel; a steering valve interposed between the pump and the steering motor to selectively control pressure fluid to the steering motor; a second fluid pump within the circuit for metering pressure fluid to the steering motor; a pressure compensator valve connected to the pump outlet by a first fluid passage and to the pump displacement control by a second fluid passage, the compensator valve adapted to maintain a constant pressure differential between the first fluid passage and a third substantially unobstructed fluid passage by continuously modulating pressure fluid to the displacement control in response to changes in steering load pressure and flow demand within the steering valve; the substantially unobstructed third fluid passage connecting the compensator valve to the steering valve, the steering valve adapted to route a steering load pressure signal taken directly from the steering valve to the compensator valve through the substantially unobstructed third fluid passage when a steering direction is selected and to isolate the third fluid passage from the steering load pressure when the steering valve is in a neutral steering position, the third fluid passage then being connected to the fluid reservoir.