| 摘要 |
PROBLEM TO BE SOLVED: To provide a hydraulic control system having excellent operability, responsiveness and stability, and remarkably improved in system efficiency thereof. SOLUTION: When each selector valve 3, 4 and 5 is positioned in a neutral position, supply of the pressure oil from a discharge line 11 of a variable displacement pump 1 to each selector valve 3, 4 and 5 is cut, while the pressure of a signal line 18 is connected to a tank 32 through an opening/closing valve 6 with a throttle. The pressure of the signal line 18 is a low pressure, while the pressure oil inside of the signal line 11 is discharged to the tank through a pressure generating means 31, resisting a spring 55 of a pressure compensating flow control valve 29. In this case, a discharge rate of the variable displacement pump is maintained at the minimum rate when the signal pressure Po working to a pump discharge rate control mechanism B is low, and an oil rate passing through the pressure compensating flow control valve becomes the minimum oil rate. When the pressure of a signal line C rises, a discharge rate of the variable displacement pump is maintained at the minimum rate. This minimum rate can be easily set at a remarkably small rate according to the structure of the variable displacement pump having the pressure generating means and the pump discharge rate control mechanism. COPYRIGHT: (C)2004,JPO
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