| 摘要 |
PROBLEM TO BE SOLVED: To apply any of a fixed capacity-type hydraulic pump and a variable displacement-type hydraulic pump, provide a suitable turning speed according to weight of suspended load in crane work, in a hydraulic drive control device of a revolving super structure-type construction machine. SOLUTION: Signals from a work mode selecting switch 20, angle sensors 21a, 21b for detecting angles of a boom and an arm, and a pressure sensor 22 for detecting pressure of a bucket cylinder 5b on the rod side are inputted to a controller 23, the controller 23 outputs a control signal responsive to a calculation result to a solenoid proportional pressure-reducing valve 19 disposed in a pilot pump line 8, and decompression is not performed by the pressure- reducing valve 19 when the switch 20 is in OFF, or the pressure-reducing valve 19 is actuated according to a position and weight of the suspended load when the switch 20 is in ON.
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