Spindle motor
 A spindle motor comprising a bracket, a shaft member secured to the bracket, a rotor rotatively supported by the shaft member while interposing bearings a rotor magnet fastened to the rotor and a stator disposed to confront the rotor magnet, wherein the rotor has a hub portion, to which a recording disk is fastened, and a rotor portion, to which the rotor magnet is fastened, the hub portion and the rotor portion being made to be interchangeable. The hub portion has a plurality of female screw holes for fastening the retaining cap, the number of a plurality of the female screw holes being different from the number of ball members of the ball bearing by at least two. 
Nagano Nidec Corporation
F G H F H F H H H H H H H
F16C G11B H02K F16C H02K F16C H02K H02K H02K H02K H02K H02K H02K
additional inventional inventional inventional additional inventional additional inventional inventional inventional inventional inventional additional
Tsuyoshi Hisashi Kenichi
Miyawaki Kono Yamazaki