Patent ID: 7726414

Claim:
A pneumatic spring hammer device, comprising: a drive piston that moves axially; a cavity formed in one end of the drive piston; an impact piston that moves axially in the cavity of the drive piston between an impact position and an idle position; a least one ventilation slot formed in the drive piston and positioned to fluidly connect an antechamber situated in front of the impact piston and a hollow space enclosed by the drive piston and the impact piston such that air can flow from the antechamber into the hollow space via the ventilation slot during impact operation of the spring hammer device; a guide tube positioned about the drive piston such that the drive piston is slidably contained therein; a plurality of idle openings passing through the guide tube; and a control element having a control opening, the control element being movable between (i) a closed position in which the control element obstructs the idle openings, thereby sealing the hollow space from atmosphere without interfering with flow from the antechamber into the hollow space via the ventilation slot, and (ii) an open position in which the control opening overlies one of the idle openings to fluidly connect the hollow space to atmosphere via the at least one ventilation slot to disable operation of the impact piston independent of the position of the drive piston.