POWER TOOL

PROBLEM TO BE SOLVED: To easily mount/demount a cooling fan by forming the motor shaft one end of an electric motor projecting from a nut for fixing the cooling fan in a noncircular cross-sectional shape. SOLUTION: A motor shaft 1 of an electric motor M is supported in a housing H through bearings 14, 15, a pinion P is formed on one end 1a, a cooling fan F is fitted to the other end 1b and a nut N is threadedly engaged. The other end 1b of the motor shaft 1 projects from the nut N, and has the part 1c having an outside diameter smaller than an inside diameter. The projecting part 1c has the flat surface 2 formed by cutting out the opposed both side parts of the outer peripheral surface, and presents a noncircular cross-sectional shape, that is, an oval cross-sectional shape. When removing the cooling fan F, the flat surface 2 of the projecting part 1c in the motor shaft 1 is sandwiched by using a tool such as a spanner, and the nut N is loosened in a state of nonrotatably holding the motor shaft 1 to thereby easily mount/demount the cooling fan F.