| 摘要 |
<p>PURPOSE:To spreading the effective utilization range of a motor output by connecting high-pressure and low-pressure pilot circuits to and unloader valve provided in an auxiliary circuit and connecting the pilot circuits with respective main circuits through a high-pressure/low-pressure selector valve. CONSTITUTION:A high-pressure pilot circuit 44 and a low-pressure pilot circuit 45 are connected to an unloader valve 40 provided in an auxiliary circuit 32. Pilot circuits 41 and 42 led out respectively from main circuits 11 and 21 are selectably connected with the pilot circuits 44 and 45 through a high-pressure/low-pressure selector valve 43. By this arrangement, the set pressure of the unloader valve 40 can be enhanced, the range where the confluence of a hydraulic oil from an auxiliary pump 30 to main circuits 11 and 21 can be enhanced, and the effective utilization range of a motor output can be spread.</p> |
