Fastener driving device having full cycle valve

Abstract From the Canadian patent

A pneumatically operated fastener driving device includes a pilot pressure operated main valve movable from a normally closed position into an opened position closing an exhaust path and allowing a supply of air under pressure to be communicated with a piston chamber to initiate and effect the movement of a piston and fastener driving element through a fastener drive stroke. First passage structure is provided between a pilot pressure chamber and an exhaust port. A secondary valve member is mounted with respect to the first passage structure so as to be movable between an opened position permitting, communication between the pilot pressure chamber and the exhaust port and a closed position …