Magnetic disk drive motor including a fixed shaft having mounted thereon a ball bearing with a rotor fixed at one end thereof and having a disc abutting the outer ring of the bearing

A magnetic disc drive motor, comprising:

• a frame;
• a fixed shaft having a lower shaft portion fixedly mounted on the frame and an upper shaft portion and defining a fixed axis;
• a ball bearing member for rotatably supporting a magnetic disc thereon, said ball bearing member including an upper and a lower ball bearing each of which has an inner ring being secured to the upper shaft portion of the fixed shaft and an outer ring for receiving a magnetic disc;
• a collar held between the outer rings of the upper and lower ball bearings mounted on the fixed shaft;
• a rotor, for mounting the magnetic disc, fixed to a lower end portion of the outer ring of the lower ball bearing, the rotor having a loading surface defined on an uppermost surface thereof, said loading surface being perpendicular with respect to the fixed axis of said fixed shaft;
• and
• a motor member including:
• a rotor member mounted in an inside of the rotor;
• and
• a stator member secured on the frame,
• wherein the upper shaft portion protrudes above the uppermost surface of the rotor such that the upper ball bearing, the collar, and at least an upper portion of the lower ball bearing are positioned above the uppermost surface of the rotor, and
• wherein an inner edge portion of the magnetic disc abuts the outer ring of at least one of the upper and lower ball bearings, and an inner peripheral portion of the magnetic disc is mounted on the loading surface of the rotor.