| 摘要 |
PROBLEM TO BE SOLVED: To decrease torque while suppressing degradation in load capacity, bearing stiffness and durability. SOLUTION: Radial bearing clearances Cra, Crab generating fluid dynamic pressure at rotating of a shaft member 10 are formed separately in a axial direction, and supporting portions 17a, 17b are formed at opposite portions to the radial bearing clearances Cra, Crab of the shaft member 10. Between the supporting portions 17a, 17b of the shaft member 10, an escape portion 18 having a diameter smaller than that of the supporting portions 17a, 17b is formed so as to be 0.5 to 4% in escape amount.
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