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US 5,701,933 AGranted
Hydraulic control system having a bypass valve
AssigneeCaterpillar Inc.
InventorStephen V. Lunzman
Life of this patent
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AssigneeCaterpillar Inc.
InventorStephen V. Lunzman
Estimating the term…
A hydraulic control system has a closed center control valve disposed to control flow of pressurized fluid from a pump to an actuator and a bypass valve disposed to control fluid flow through a bypass line connecting the pump to a reservoir. A controller connected to the control valve and the bypass valve is operative to controllably move the control valve toward an open, flow communicating position and the bypass valve toward a closed flow blocking position. A pressure compensating valve is disposed in the bypass line to maintain a predetermined pressure differential across the bypass valve when the pressure upstream of the bypass valve exceeds a predetermined level so that the flow through a area opening in the bypass valve is substantially commensurate with the opening at pressures above the predetermined level.
A hydraulic control system having a pump for delivering pressurized hydraulic fluid from a reservoir, a closed center control valve disposed between the pump and an actuator to control flow of pressurized fluid fed to the actuator, a bypass line connecting the pump to the reservoir, a bypass valve disposed in the bypass line to control fluid flow therethrough and biased to an open flow communicating position, and a controller connected to the control valve and the bypass valve and being operative to controllably move the control valve toward an open, flow communicating position and the bypass valve toward a closed flow blocking position, comprising:
Dependencies are inferred from the claim text.