| 摘要 |
A hard disc drive is disclosed, which comprises a compound bearing assembly including a stepped shaft 1 having a large-diameter portion 1a and a small-diameter portion 1b, the large-diameter portion 1a having an inner raceway groove 2a formed in the outer periphery, an outer race ring 3 surrounding the large-diameter portion 1a and having an outer raceway groove 2b, a plurality of balls 4 provided between the inner and outer raceway grooves 2a and 2b, a ball bearing unit 5 having an inner and an outer race ring 5a and 5b and a plurality of balls 6 provided therebetween, the inner race ring 5a being fitted on the small-diameter portion 1b, and a sleeve-like spacer 7 surrounding the stepped shaft 1and having opposite end small-diameter portions, the outer race ring 3 and the outer race ring 5b of the ball bearing unit 5 being fitted on the opposite end small-diameter portions, respectively. The bearing assembly is provided as a complete product and assembled by the hard disc drive manufacturer in the hard disc drive motor by fitting it on a rotor hub thereof.
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