| 摘要 |
<P>PROBLEM TO BE SOLVED: To solve a cost increase of a whole system even though a fixed pump with a constant discharged amount is provided in addition to a variable pump prepared for load sensing control. <P>SOLUTION: The variable pump 11 is provided to maintain a slant rotary position capable of discharging a designated amount at a neutral situation. The hydraulic control system is provided with an unloading valve 80 returning working oil discharged from the variable pump 11 to a tank 19 until maximum load pressure PLS is reached to designated pressure in a supply passage 17 of the variable pump 11, and a pressure reducing valve 90 reducing working oil supplied to the unloading valve 80 to designated pressure and supplying the designate pressure as a pilot pressure source of a control valve 50. Thus, a response property of the variable pump 11 is improved at a low cost. <P>COPYRIGHT: (C)2004,JPO |
