| 摘要 |
A hydraulic control system for a hydraulic excavator of the present invention comprises a boom control valve in a first oil path for providing pressure oil from a first hydraulic pump with a boom cylinder according to operation of a boom operating means, an arm control valve in a second oil path for providing pressure oil from a second hydraulic pump with an arm cylinder according to operation of an arm operating means, a confluence switching valve having a confluence position for joining the paths and a confluence stop position for stopping the confluence, a flow control valve for returning pressure oil in the first oil path to a tank, and a control means for controlling the valves, so as to switch the confluence switching valve to the confluence position and close the flow control valve when the arm operating means is operated independently and so as to switch the confluence switching valve to the confluence stop position and open the flow control valve when both of the operating means are operated simultaneously, thereby, the arm pulling operation is performed independently, an arm cylinder speed increases and a leveling efficiency is improved. |
