A portable power tool including, within a housing: an electric motor having a drive shaft, an epicyclic reduction gear having planetary gears meshing with a central gear of the drive shaft of the electric motor, the reduction gear being provided with an output shaft that is rigidly connected to a ball screw of a ball screw/nut mechanism and is coaxial to the ball screw, and a support bearing connecting the output shaft to the housing. The tool includes at least one stabilization bearing axially offset relative to the support bearing. The stabilization bearing connects the output shaft of the epicyclic reduction gear to the housing by at least one intermediate part selected from: the drive shaft of the electric motor, planet-carrier axles of the epicyclic reduction gear, and epicyclic reduction gears of the epicyclic reduction gear. The structure is of use in shears, in particular sheet metal shears.
