| 摘要 |
PROBLEM TO BE SOLVED: To enhance the operability of an actuator to which combined oil is supplied after controlling the amount of combined oil to an adequate level. SOLUTION: Combined oil from first and second hydraulic pumps 1, 17 is supplied to bucket cylinder Bc and a high speed operation is started. At that time, a combined oil switching valve 2 and a cut valve 23 are opening-controlled by the secondary pressure from the electromagnetic proportion valve 40 based on an output signal from a controller 39 in response to the amount of bucket operation, and the amount of combined oil from the second hydraulic pump 17 is controlled.
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