Patent ID: 6170261
Filing Date: 2001-01-09
Classification: E02F,F15B

Abstract:
A pressurized hydraulic fluid supply apparatus comprising:a first circuit having a first hydraulic pump, a first hydraulic actuator connected to a delivery passage of the first hydraulic pump, a first directional control valve for controlling the first hydraulic actuator, and a first pressure compensation valve for making constant a pressure difference between upstream and downstream pressures of the first directional control valve;a second circuit having a second hydraulic pump, a second hydraulic actuator connected to a delivery passage of the second hydraulic pump, a second directional control valve for controlling the second hydraulic actuator, and a second pressure compensation valve for making constant a pressure difference between upstream and downstream pressures of the second directional control valve;a third circuit having a third hydraulic actuator connected to the delivery passage of the second hydraulic pump, a third directional control valve for controlling the third hydraulic actuator, and a third pressure compensation valve for making constant a pressure difference between upstream and downstream pressures of the third directional control valve; anda merge/separation valve for merging and separating the delivery passage of the first hydraulic pump and the delivery passage of the second hydraulic pump;wherein the merge/separation valve is set to a flow merging state by driving of the third hydraulic actuator; andwherein the merge/separation valve is set to a flow separation state by a load pressure of the first or second hydraulic actuator unless the third hydraulic actuator is being driven.