| 摘要 |
PURPOSE:To surely perform change-over of ports by disposing an acceleration piston at the end of a case so as to transmit the motion of the acceleration piston to a spool via an acceleration spring. CONSTITUTION:As an oil pressure from oil supply parts 11a and 11b is increased, a spool 12 starts to be shifted left. In the operation, grooves 11e and 11g are first closed by flanges 12b and 12c, respectively. As the spool 12 makes additional left shifting, a groove 11f is opened. Hydraulic oil is thereby supplied from an oil supply port 11a to the back of an acceleration piston 17, so that the piston 17 starts to be shifted left. Then, an acceleration spring 18 is compressed, and the spool 12 is quickly shifted to communicate the ports 11b and 11c with each other. The range of working pressure may be arbitrarily adjusted by regulating the stroke of the acceleration piston 17 by means of a screw rod 19. |
