| 摘要 |
PURPOSE:To prevent the stoppage of turning during the composite operation with a turning motor for increasing the speed of an arm cylinder during the single operation of the arm cylinder by providing a parallel circuit with a check valve and a sequence valve and a bypass circuit from other pump to the arm cylinder of an oil-pressure shovel. CONSTITUTION:During the synchronous operation of an arm cylinder 6 and turning motors 7 and 8, the motors 7 and 8 are driven by a pressure properly set for a sequence valve 3. Since, in this case, an excess oil coming into the motors 7 and 8 passes through the sequence valve 3 to operate the cylinder 6, the stoppage of the motors 7 and 8 due to the flow of all oil in the cylinder 6 of small load does not occur. During the single operation of the motors 7 and 8, since the check valve 5 is provided even when the sequence valve 3 is opened, direct application of pressures to the motors 7 and 8 directly through a tank 19 does not take place. Also, during the operation of the cylinder 6, oil is supplied to a switch valve 12 through a neutral pass 22, a tandem pass 18, and the check valve 5, whereby the oil of other pump is directed from the pass 16 into the passes 17 and 18 and the speed of the cylinder is increased. |
