PILOT-OPERATED FIVE-WAY TWO-POSITION SPOOL-TYPE PNEUMATIC DIRECTIONAL VALVE MECHANISM

When compressed (pilot) air is admitted through threaded port a in cover 1 (Fig. a), spool 2 is shuttled to the right. At the same time air passes through a metering orifice in a connection and central channel in spool 2 and begins to fill space 3. As the space is filled, the pressure in it rises. Since the effective area of the spool at its right end is twice that at its left end, owing to the provision of auxiliary plunger 4, after a certain time delay plunger 4 shuttles spool 2 to the left, back to its initial position. The length of the time delay depends upon the volume of space 3 and can be regulated by changing this volume. This is done by turning screw 5 which adjusts piston 6 vertically. The directional valve is operated after the arrival of incoming pilot air at port a and, after a time delay, is returned to its initial position without shutting off the pilot air at port a. The principle of the valve is shown schematically in Figs. b and c.
$3666$SHP,FC$