Patent ID: 7032687

Claim:
A percussion device comprising: a housing with first and second bodies inside said housing; said first and second bodies being movable relative to each other along a common geometric axis, said first body carrying an impact pin protruding from said housing, said second body counterbalancing impact motions of said first body so as to damp vibrations of the device, said second body being rotatable and said first body not being rotatable, and at least one of said first and second bodies having a surface that is oblique to said geometric axis that, by contact with a portion of the other of said first and second bodies, transforms rotary motion of said second body into axial motion of said first and second bodies; first and second springs that urge said first and second bodies towards each other and against which said first and second bodies are separated axially; a driving source connected to said second body via a drive spindle that is rotatably mounted in a bearing member, said bearing member being axially movable but not rotatable in relation to said housing; said second spring being a helical pressure spring with a first end attached to said housing and with a second end attached to said bearing member to urge said bearing member and said second body towards said first body and to prevent rotation of said bearing member; and a third spring between said first body and said second body, said third spring having a strength that keeps said first and second bodies separated while said impact pin is unloaded and maximally protruded.