Abstract: A rotary electric tool in which a differential gear mechanism is mounted within a gear case fixed to a housing for example; projections are formed on the outer peripheral surface of an internal gear of a final planetary gear mechanism in the differential gear mechanism, the said projections being brought into engagement with a projection-formed surface of a torque adjusting cam; the internal gear and the torque adjusting cam can be changed in relative position axially by reaction force of the internal gear; and the rotation of an output shaft is changed over between high and low speed conditions according to an axial displacement of the internal gear.

Abstract: A differential gear mechanism is mounted within a gear case fixed to a housing, an intermediate gear and a clutch mechanism are disposed on at least one output side, and a rotation changes for changing over the rotation of both output shafts between synchronous rotation and independent rotation according to increase or decrease in load relative to a present torque value.

Abstract: The present invention relates to an improvement in an electric tacker covered by a motor battery operated for hammering inverted U-shape needles, T-shape tacks or nails or inverted L-shape staples, and more specifically to an improvement in a continous hammering preventive mechanism for needles tacks, nails or staples, including a staple idle hammering mechanism and a mechanism for displaying the remaining quantity of staples.