| 摘要 |
<p>PURPOSE:To prevent the lowering of the operating speed of a construction machinery by setting up its speed regardless of load by providing a constant flow liquid source to each of grouped construction machines for a liquid pressure circuit by which plural construction machines can be concurrently operated as in motorized grader. CONSTITUTION:When a switch valve 14 is in neutral position, discharge flow Q1 from a pump 4 is diversed and supplied to operating valves 1 and 2. And, the first demand valve 11 is operated by a spring 11a against a pressure difference before and behind a throttle valve 8, and the discharge flow Q2 is joined with a stationary pump 1 on the upstream side of the throttle valve 8 and further with the stationary pump through the valve 11 and the check valve 12. When the revolving speed of the engine is increased and discharged flow rates Q1, Q2 and Q3 to each pump 4 to 6 are raised, the position of the valve 11 is switched. Thus, part of discharge flow rate Q3 of the stationary pump enters through the port 113 of the valve 11 into a pepeline 20 and then supplied to the operating valve 3 side, so that the amount of liquid coming into the stationary pump 5 is reduced.</p> |
