Magnetic disk drive apparatus having disk clamp attachable using a single fastener

A magnetic disk drive comprising:

• a center fixed shaft;
• a bearing mounted on the center fixed shaft, said bearing including an inner ring contacting the center fixed shaft, and an outer ring, said bearing being given a preload axially along the center fixed shaft;
• a hub being rotatably supported by the bearing and driving a magnetic disk while having the magnetic disk attached to the outer circumferential surface thereof;
• a drive magnet fixedly secured to the hub;
• a stator core secured to a frame portion so as to confront the drive magnet;
• and
• a clamp cap member for closing a center hole of the hub is arranged on a distal end portion of the hub, the clamp cap member including a tap hole for screwing a disk clamp to clamp the magnetic disk, the tap hole being formed at the center of the clamp cap member,
• wherein an end surface of said outer ring of said bearing contacts said clamp cap member, whereas a gap is defined between an end surface of said inner ring of said bearing and said clamp cap member.