| 摘要 |
PURPOSE:To prevent impact pressures from being generated at a tank port and a drain core, by a method wherein a damping valve is provided between a junction point of a bypass passage and a return passage and a tank port, and a drain core for recovering a drain leaked out from the return passage has an end opened between the damping valve and the tank port, in a direction change-over valve. CONSTITUTION:The bypass passage 14 and the return passages 13A, 13B are joined to each other at a part A, and the damping valve 20 for impact pressures is provided in a passage 19 extended from the junction point to the tank port 5. The drain cores 31A, 31B provided between a return oil passage 13 and oil seals 17, 18 recover the drain leaking out through the outside periphery of spools 8, 9. Accordingly, even when impact pressures are generated in the passage 14 or the passages 13A, 13B at the time of changing over the spools, the pressures are prevented from acting directly on the seals 17, 18 or acting on the part between the tank port 5 and a tank 4. |
