Pneumatic fastening device having improved nose sealing arrangement

Abstract

A pneumatically operated fastener drive device that comprises a housing assembly including a nose assembly defining a fastener drive track. A cylinder is disposed in the housing assembly, and a resilient bumper is disposed towards a bottom of the cylinder. A drive piston is slidably and sealingly mounted in the cylinder for movement through an operative cycle. The drive piston engages the bumper at the end of the drive stroke. A fastener driving element is operatively connected to the piston for movement therewith and extends through an opening in the bumper. A valve arrangement is movable between a closed position and an opened position to effect movement of the piston and fastener driving element. An actuator and trigger member are operable to control the valve arrangement. The bumper has a sealing portion surrounding the opening in the bumper and disposed outwardly from the cylinder. The sealing portion has exterior surfaces disposed in engagement with adjacent surrounding surfaces of the nose assembly. The sealing portion is flexible outwardly under the force of air pressure within the cylinder below the piston during the return stroke of the piston so that the exterior surfaces of the sealing portion are biased in sealing relation with adjacent surrounding surfaces of the nose assembly.