Through port 1 (Fig. a), compressed air flows to port 2 and further to the air chamber of the first operating device. When the pressure in this chamber has reached a certain preset limit, valve member 3 opens, overcoming the resistance of helical spring 4, and air is admitted through port 5 to the chamber of the second operating device. In this way, consecutive operation of two devices is obtained. The pressure at which the valve is operated can be regulated by adjusting the force exerted by spring 4. This is done by turning threaded member 6. The principle of the valve is shown schematically in Figs. b and c.
$3633$SHP,Va$