| 摘要 |
<p>PURPOSE:To allow a swivel motor to be preferentially operated and simultaneously to attain regeneration of an arm cylinder, by providing a fluid passage in association with a direction selector valve for a spool in a hydraulic control device for a power shovel. CONSTITUTION:When a direction selector valve 34 and a spool 3 are in their neutral position, oil in a pump 9 is returned to a tank 10. When the spool 3 is switched to its left position, pressure in a pressure chamber 23 and a bottom side chamber 6 becomes a pump pressure with the aid of a communication port 35. Return oil in a rod side chamber 7 is returned to a tank 10, and a regenerative spool 19 is moved by the difference between decrease in the pump pressure due to load of an arm cylinder 1 in the direction as depicted by 29 and increase in pressure in a pilot chamber 32, thereby entering oil into a high pressure flow line 12. On the other hand, when the spool 3 is switched to its right position, the pump 9 is brought into communication with the rod side chamber 7, thereby maintaining the hydraulic pressure at a high level. When the direction selector valve 34 is switched, a swivel motor 33 is rotated, and the same operation as the above by the reciprocal movement of the spool is effected with the exception that the pressure chamber 23 receives no pressurized oil from the pump. Thus, in the case that the swivel motor 33 and the arm cylinder 1 are simultaneously operated, the former is preferentially actuated relative to the latter.</p> |
