| 摘要 |
PROBLEM TO BE SOLVED: To provide a hydraulic drive system of a construction machine capable of detecting a revolving single operation or an operation corresponding thereto with a simple constitution, and reducing a relief amount in starting revolving when the operation is detected.SOLUTION: A hydraulic drive system of a construction machine includes a revolving control valve 41 disposed on a first circulation line 21 extended from a first pump 15, a boom control valve 51 disposed on a second circulation line 31 extended from a second pump 17, first and second regulators 16, 18 changing tilt angles of the first and second pumps, and a control device 8 controlling one or a plurality of electromagnetic proportional valves 61, 62 outputting a second pressure to the first and second regulators. The control device lowers first and second horsepower control lines for limiting discharge flow rates of the first and second pumps when a discharge pressure of the first pump is higher than a first set value, and a discharge pressure of the second pump is lower than a second set value during a revolving operation.SELECTED DRAWING: Figure 1 |
