Patent ID: 8162727

Claim:
A motor-driven machine tool ( 1 ) comprising: a rotatably driveable tool ( 6 ); a drive shaft ( 4 ) driven by a drive unit ( 2 ); an output shaft ( 5 ) on which the tool ( 6 ) is mounted; an eccentric coupling device ( 7 ) for transferring the rotational motion of the drive shaft ( 4 ) to the output shaft ( 5 ) via an eccentric coupling motion; a mass-balancing device ( 10 ) for oscillation compensation, the mass-balancing device ( 10 ) being operatively connected to the drive shaft ( 4 ) and implementing a compensation motion counter to the eccentric coupling motion, wherein the mass-balancing device ( 10 ) includes a mass-balancing member ( 11 ) and a first eccentric member ( 12 ) which is mounted on the drive shaft ( 4 ), the mass-balancing member ( 11 ) being operatively connected to the first eccentric member ( 12 ) wherein the eccentric coupling device ( 7 ) includes a coupling member ( 8 ) and a second eccentric member ( 9 ) which is mounted on the drive shaft ( 4 ), the coupling member ( 8 ) being operatively connected to the second eccentric member ( 9 ), and wherein the first and second eccentric members are designed as eccentric cams ( 9 , 12 ) which are fixedly connected to the drive shaft ( 4 ), and wherein the coupling member ( 8 ) and mass-balancing member ( 11 ) bear against the contour of the respective eccentric cams ( 9 , 12 ).