Compressed air is supplied from the main to port 1 (Fig. a), two channels in the valve body and through throttling orifices 12 (Fig. b) into end spaces 2 and 3. At this, ports 4 and 5 are shut off by two-port pilot valves and spool 11 is in the position shown in Fig. a. In this position air is admitted from port 1 into port 6, which is connected to one end of the operating cylinder or device. Port 7 is connected to port 8, which leads to the atmosphere. If the two-port valve connected to port 4 is opened, then, in case the flow of air through the connecting pipeline and valve is greater than the amount admitted through throttling orifice 12 (Fig. b), the pressure in end space 3 drops and that in end space 2 remains constant. Owing to the difference in pressure, piston 9, spool 11 and piston 10 are shifted to the right. To prevent excessive loss of air at the end of the stroke since the two-port valve may remain open, piston 10 disconnects end space 3 from port 4. After the spool is shuttled, air from port 1 is admitted into port 7 and further to the actuator (operating cylinder or device), and port 6 is connected to the atmosphere through port 8.
$3680$SHP,FC$