| 摘要 |
PURPOSE:To prevent a zigzag motion and the change in the speed of swinging and that of an arm at the time of simultaneous operation of swinging-running by providing a two-position selecting valve in a pipe line connecting a hydraulic pump with a running selection valve and an arm selection valve. CONSTITUTION:A swing selection valve 9 is connected with the 1st hydraulic pump 2 in the hydraulic circuit of the hydraulic shovel, while the 2nd right-running selection valve 12 is connected with the 2nd hydraulic pump 3. And the 1st running selection valve 6 and the arm selection valve 7 are connected in tandem with the swing selection valve 9. In the pipe line 21 connecting the 2nd hydraulic pump 3 with the 1st left-running selection valve 6 and the arm selection valve 7 is provided the two-position selecting valve 22 which closes the pile line 21 at a position A and opens the line at a position B. Between two pipe lines connected with a swing motor 15 is provided a shuttle valve 27, whereby the pressure on the high-pressure side is supplied to the pilot ports of the two-position selecting valves 22 and 24. The two- position selecting valves are set at the position B only when the swing motor operates. |
