Driving tool with air-cooled bumper

Abstract From the Canadian patent

A driving tool comprising a cylinder, a piston movable axially within the cylinder a driving, element movable conjointly with the piston so as to move through a central aperture of an end wall of the cylinder in a driving stroke and in a return stroke and a bumper, which arrests movement of the piston toward the end wall of the cylinder in a driving stroke. The bumper is made of resilient material such as a cast polyurethane, in an annular shape. The bumper has a plurality of slots extending radially from each of its inner and outer peripheral surfaces and extending axially between its opposite ends. Each of a plurality of ports in a wall of the cylinder, either the end wall or a …