FIVE-WAY THREE-POSITION SPOOL-TYPE PNEUMATIC DIRECTIONAL VALVE MECHANISM

When there is no incoming pilot air through ports e and f, i.e. when these ports and the end spaces of spool 6 are connected to the atmosphere, spring 7 slides out two pins 8 (Fig. a). The length the pins protrude from the ends of spool 6 is limited and adjusted by special nuts and, consequently, spool 6 is located accurately in the central position. In this position, ports 2 and 3, connected to t…