| 摘要 |
<p>A working machine such as a hydraulic excavator is provided with a working apparatus (6) including a boom (7) pivotally mounted on the body (1, 2) of the working apparatus (6) and a boom-cylinder hydraulic system for the working apparatus (6). The hydraulic system includes an actuator (10) for moving the boom (7) up and down and a directional selecting valve (16). The directional selecting valve (16) is arranged to effect selective switching of the feed of a pressurized working fluid to and the discharge of working fluid from with respect to the rod-side (10A) and the bottom-side hydraulic chamber (10B). The hydraulic system further includes a device (21:51, 53, 55:51, 53, 63:51, 53, 72:101, 102, 104:53, 141, 142:53, 151, 152) for relieving the pressure of the bottom-side hydraulic chamber (10B) of the actuator (10). This release device is connected to the bottom-side hydraulic chamber (10B) of the actuator (10) via a hydraulic circuit (13-16). When the pressure in the bottom-side hydraulic chamber (10B) changes from rise to fall, the pressure is released to a low-pressure side of the hydraulic circuit (13-16), thereby suppressing oscillation of the boom (7).</p> |
