| 摘要 |
PROBLEM TO BE SOLVED: To reduce fuel consumption by reducing a load acting on an engine by automatically lowering a pilot primary pressure without asking an operator's help when a construction machine is not operated. SOLUTION: A pilot primary oil passage 12 extending from a pilot hydraulic power source 11 to a remote control valve 13 is provided with a branch oil passage 20 communicating with a tank 17. A first electromagnetic valve 21 is located in the branch oil passage 20, and also a second electromagnetic valve 23 is located at the downstream side of the first electromagnetic valve 21. When a non-operation state of the construction machine is detected by an operation detecting means 19, the pilot primary pressure is lowered by opening the branch oil passage 20 by switching the first electromagnetic valve 21 through the control of a controller 30. When an oil temperature detecting means 25 detects that oil temperature has exceeded the required temperature, an unnecessary pressure drop is suppressed by switching the second electromagnetic valve 23 to "throttled small position" through the control of the controller 30. COPYRIGHT: (C)2004,JPO&NCIPI
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