| 摘要 |
PROBLEM TO BE SOLVED: To provide a hydraulic control device allowing the non-stage setting of the maximum supply amount to an actuator connected to a preliminary change-over valve. SOLUTION: The hydraulic control device comprises combined flow passage 34, 37 formed by combining the most downstream portions of a plurality of circuit systems A-C consisting of open-center type change-over valves connected to a pump, a flow control restriction 43 provided in a flow passage for supplying a pressure oil to an actuator for a preliminary change-over valve 26 provided in the combined flow passages, a flow control valve 42 provided in a discharge flow passage 41 communicating the combined flow passages with a tank, a pressure setting mechanism 47 provided in the flow control valve 42 for setting a pressure generated on the upstream side thereof, a first pilot line 45 for guiding a pressure generated on the upstream side of the flow control restriction to one pilot chamber 42a of the flow control valve, and a second pilot line 46 for guiding a pressure generated on the downstream side of the flow control restriction to the other pilot chamber 42b of the flow control valve.
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