Compressed air, supplied from the main to port 1, is admitted through the channel in spool 4 to the left end space of the spool, holding spool 4 in the position shown in Fig. a. At this, air from port 1 is admitted into port 2. When palm button d of pusher 5 is pressed, spool 4 is shifted to the left and connects port 2 to port 3, which is connected to the atmosphere. The principle of the valve is shown schematically in Figs. b and c.
$3687$SHP,FC$