Patent ID: 7044151

Claim:
An apparatus, comprising: a mount having an aperture; a piston adjacent to said mount and having an aperture, said piston being of a shape for defining a movement direction of the piston; a shear pin having one end press fit into the aperture in said mount and another end inserted through a sleeve into the aperture in said piston, said shear pin restraining the piston relative to the mount; a hammer region formed on said piston and located in the movement direction of said piston; a strikable part mounted in the movement direction of the piston from said hammer region and separated from the hammer region by a gap, said strikable part sealing a flowpath of gas in said apparatus, said hammer region striking said strikable part upon movement of the piston in the movement direction through said gap; and a stationary part connected to said strikable part by a shearable link, said strikable part being separated from said stationary part upon being struck by said hammer region with an input force for shearing said shearble link; said shear pin being constructed to be shearable with less input force than the input force for shearing said shearable link so that the gas does not flow in the apparatus when said shear pin is initially sheared, but gas does flow when both said shear pin and said shearable link are sheared and said strikable part is separated from said stationary part; said sleeve comprising an outer surface and an eccentric bore surrounded by said outer surface for receiving said shear pin, said eccentric bore being parallel to and not coaxial with the outer surface of said sleeve.