| 摘要 |
PURPOSE:To surely perform change-over of ports by providing a spool with pressure receiving faces to which a liquid pressure is applied when the ports are changed over. CONSTITUTION:When a pressure is reduced until a spool 12 is changed over to the oil discharge side, the interior of a hole 17 is communicated to an oil discharge port 11d to reduce the pressure. Then, the spool 12 is quickly shifted right by the force of a spring 14. When a pressure of the hydraulic oil which is supplied from oil supply ports 11a and 11b into a case 11 increases until the pressure exerted on pressure receiving faces 13a and 13b surpasses the force of the spring 14, the spool 12 starts to be shifted left. Once the oil supply port 11b is communicated to a groove 11e, namely, the interior of the hole 17, the spool 12 is quickly shifted to surely perform change-over of the ports. |
