Patent ID: 8955616
Filing Date: 2015-02-17
Classification: B25D

Abstract:
1. A percussion tool driven by pressurized air for demolition or breaking work, and connectable to an insert tool via a tool holder, said percussion tool comprising a percussion cylinder, a piston arranged to travel in the bore of the percussion cylinder, and a valve unit which alternatingly during operation connects the upper or lower end of the percussion cylinder to a source of pressurized air, which is connectable to the percussion tool, thereby enabling a repeated reciprocating motion of the piston, wherein the insert tool connected to the percussion tool performs repeated striking motions under the action of the piston, said percussion tool being further arranged so that the axial striking position of the piston in the bore of the cylinder, which corresponds to the position of the piston where the energy of the piston is transmitted to the connected insert tool, is dependent on a feeding force by which the percussion tool, via the connected insert tool, is pressed against an object being worked, the percussion tool further comprising an elastic buffer arranged to, during operation, absorb the impact energy not transmitted to the object when the striking position of the piston is furthest downward, which corresponds to the position of the piston when the feeding force is at or below a predetermined value, wherein the percussion tool comprises means for automatically preventing the reciprocating motion of the piston at a predetermined degree of wear on the buffer when the feeding force is at or below said predetermined value, said percussion tool including means for selectively overriding said means for automatically preventing said reciprocating motion only after said reciprocating motion has stopped.