| 摘要 |
<p>PURPOSE:To enable soil to be excavated and discharged quickly, by providing a hydraulic circuit for connecting a rotary motor to a change-over valve for swing, with a speed-regulating valve for enabling the opening to be freely set. CONSTITUTION:When the set pressure of a pilot pressure-reducing valve 12 is set to be 0, then the pressure of the pilot duct line 11 of a pilot hydraulic circuit comes to approx. 0. A speed-regulating valve 9 is put at a position 9a for full admission by the pressure of a spring 10, and the inflow of pressure oil fed from a first hydraulic pump 1 to a rotary motor 8 is not limited. In case that a boom is quickly taken to a high position, when the set pressure of the pressure-reducing valve 12 is heightened, then pilot pressure is worked on the regulating valve 9 through the duct line 11, and the opening is narrowed down, and the inflow of the pressure oil to the motor 8 is suppressed. Accordingly, the limited pressure oil is conducted to the increased speed circuit of the boom by the limited component, and the rising speed of the boom is increased.</p> |
