| 摘要 |
PROBLEM TO BE SOLVED: To reduce an operating burden during dismantling work using a crushing machine by a simple configuration and prevent abrasion powder generated by operation of a fluid control valve from flowing in to a directional control valve.SOLUTION: A hydraulic control device for a hydraulic shovel includes: a directional control valve 140 for controlling a flow of pressure oil supplied from a hydraulic pump 130 to a hydraulic cylinder 190; a fluid control valve 181 installed in a relief oil passage R1 to control pressure of a bottom chamber 191; and control means 120. When the pressure P of the bottom chamber 191 is equal to or higher than a first predetermined value PH and an automatic mode is set by using an automatic mode switch 157, the control means 120 performs continuous operation control for repeating in a predetermined cycle T a low pressure control for controlling the fluid control valve 181 so that the pressure of the bottom chamber 191 reaches a second predetermined value PL lower than the first predetermined value PH and high pressure control for controlling the fluid control valve 181 so that the pressure of the bottom chamber 191 reaches the first predetermined value PH. |
