Patent ID: 7719146

Claim:
A power tool, comprising: a cylindrical-shaped yoke; magnets provided in an interior of the yoke; an armature disposed rotatably in the interior of the yoke; a cooling fan rotatably secured to the armature; a fan guide disposed on a periphery of the cooling fan; a cylindrical-shaped housing, structured by connecting a front division part and rear division part, having the yoke mounted in a barrel of the rear division part, wherein the fan guide contacts an axial-direction of one end face of the yoke and is engaged with the yoke in a rotational direction thereof, and wherein the fan guide has an outer shape following the inner peripheral shape of the barrel portion of the rear division part of the cylindrical-shape housing; rotation prevention means for preventing rotation of the yoke, said rotation prevention means being provided on an axial-direction of the other end face of the yoke; and a dust guard mounted on the yoke and projecting outwardly therefrom in an axial direction beyond the axial-direction of the other end face of the yoke, said dust guard being engaged with the yoke at the axial-direction of the other end face of the yoke, and wherein the rotation prevention means comprises: a first engaging portion formed on the dust guard and a second engaging portion formed in the cylindrical-shaped housing which engages with the first engaging portion in a rotational direction.