“A” Pilotair® Pneumatic Directional Control Valves Panel-Mounted Valves, Three-Way Operation
In release position, as shown, the valve disc seats on the inlet valve
seat and seals the passage from the inlet to the outlet port. The outlet port is vented to atmosphere through the center of the plunger.
As the plunger is forced downward by the cam force it seats on the
valve disc. This seals the passage between the outlet port and atmosphere.
Further downward travel of the plunger unseats the valve disc from
the inlet valve seat and allows inlet air pressure to flow to the outlet