| 摘要 |
A hydraulic shovel drive system includes a cylinder for driving an operating section, which is an arm or a bucket. Operating oil is supplied from a hydraulic pump to the cylinder through a control valve. A relief line is branched from a rod-side supply/discharge line, and the relief line is closed or opened by a restriction device. At the time of supplying operating oil to the cylinder through a head-side supply/discharge line, the restriction device is controlled by the control device so as to close the relief line if pressure detected by a load detector is lower than a predetermined value, and so as to open the relief line if pressure detected by the load pressure detector is higher than or equal to the predetermined value. |
