| 摘要 |
PROBLEM TO BE SOLVED: To provide a hydraulic control device for a power shovel using a variable delivery pump to control an output horsepower to be a specified value or less by detecting the maximum load pressure of an actuator. SOLUTION: A switching position of a pilot switching valve 1 for controlling a motor is regulated and controlled by control cylinders 6, 7, and a timer valve 10 to supply pressure fluid to the control cylinders 6, 7 or prohibit supply of it is provided, the timer valve 10 introduces a pilot pressure for changing selector valves 1-3 to a pilot chamber 11 to which one end of its spool is faced, a restoration mechanism F is provided on the other end side of the spool provided with a holding spring 16, the restoration mechanism F is provided with a pressure chamber 12 to introduce the pilot pressure through a timing restrictor 13, and a piston 14 faced to a pressure chamber 12, and a pressure receiving area of the piston 14 is set to be larger than a pressure receiving area of one end of the spool, thereby spring force of the holding spring 16 is applied to the opposite side of the pressure receiving face of the piston 14.
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