| 摘要 |
<p>PURPOSE:To perform concurrent operation smoothly and certainly by releasing the combined function of one combined valve upon which larger load pressure acts of two combined valves at the time of the concurrent operation of hydraulic change-over valves for a work device. CONSTITUTION:Combined valves 12, 13 are respectively provided between lines 36, 44 which are connected to branch lines 41, 42, and lines 43, 45 which lead to the upperstream side of hydraulic change-over valves 6, 9. When the hydraulic change-over valves 6, 9 are operated at the same time, the combined function of one combined valve upon which larger load pressure acts of the combined valves 12, 13 is released. With this arrangement, one hydraulic change-over valve upon which larger load pressure acts of the hydraulic change-over valves 6, 9 is guaranteed the inflow of the whole quantity of the delivery pressure oil of one of two main pumps 2, 3, and thereby irrespective of the largeness of generated pressure by a load, concurrent operation can be performed smoothly and certainly.</p> |
