Patent ID: 6857548

Claim:
An explosively operated tool, comprising a housing; a barrel assembly mounted within the housing; a piston within the barrel assembly and actuated upon firing of the tool to drive a fastener in the forward end of the barrel assembly into a substrate, wherein the barrel assembly is mounted for axial movement within the housing and co-operates with a mass mounted for rearwards movement relative to the housing in opposition to a biasing force to absorb recoil on firing of the tool; and a resetting mechanism for resetting the piston into a rear part of the barrel assembly after firing, said resetting mechanism being powered in response to displacement of said mass on recoil; wherein the resetting mechanism comprises engagement means for engaging the piston in a forward position in the barrel; and displacement means for automatically displacing the engagement means rearwardly relative to said housing to thrust the piston rearwardly relative to said housing, said displacement means comprising an energy source in which energy is stored as a result of displacement of the recoil mass upon recoil.