| 摘要 |
PURPOSE:To simplify the circuit constitution by transferring a pilot operation valve provided on a parallel passage to a free flow passage position or a throttle passage position by means of the difference of operating pressures of a plurality of actuators. CONSTITUTION:Neutral paths 15-18 of control valves 10-13 are connected in tandem and a pilot operation valve 33 is provided on a parallel passage 21. When a valve 13 is operated alone, a motor 22 side is at a low pressure and the valve 33 is placed at a free flow passage position 36 which is a normal state. When the valve 12 is operated to place the valve 13 at the right position, a cylinder 23 is under a higher load pressure than that of a motor 22, thus the valve 33 is not moved. Next, when the valve 13 is placed at the left position, a passage 30 is made at a tank pressure and the pressure in a pilot chamber 35 is made lower than that of a pilot chamber 34, and the valve 33 is transferred to a throttle passage position 37, thus squeezing the feed of the pressure oil into the cylinder and preventing the pressure oil from being fed restoratively during the descending stroke of the cylinder. |
