| 摘要 |
A data storage disc drive unit 1 comprises a brushless d.c. electric motor 2 having a central stator structure 3 surrounded, in a concentric manner, by a co-operating rotor structure 4. The stator 3 and surrounding rotor 4 together define a small annular gap 5, which is used to establish a plain, sell-acting, air bearing film between the stator 2 and rotor 4. The drive unit 1 is also provided with rotor thrust bearing means 6 operable to restrain axial movement of the rotor 4 relative to the stator 2 and along the rotational axis 7 of the rotor. The magnets 29 and 18 are aligned with each other and are of opposite polarity, whereby they mutually attract to each other. This attraction urges the rotor 4 in the direction of arrow 30, pre-loading the ball bearing 20 and restraining axial movement of the stator 4 in a direction opposite to that indicated by arrow 30, so as to hold the rotor 4 in place, regardless of the attitude of the drive unit 1. <IMAGE>
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