US Patent 7191847 Drive for a motor-driven hand-held tool

A drive for a motor-driven hand-held tool includes a motor (17) and a gear mechanism (20) for converting a rotational movement of the motor (17) into a reciprocating movement of the reciprocating drive element (30) for a working tool, with the gear mechanism (20) having a transmission element (23) axially secured on a support (21) with a support member (26) and including a mass-balance member (31), a first eccentric take-off element (24) cooperating with the reciprocating drive element (30) and a second eccentric take-off element (25) cooperating with the mass-balance member (31) for imparting reciprocating movement thereto, and with the support member (26) forming a slide support surface for the mass-balance member (31).