| 摘要 |
PURPOSE:To prevent galling of a shaft and drying up of oil film by making up the inside diameter of a bearing of a small diameter part and a circular-arc shaped large diameter part, so that the part changing from the small diameter part to the large diameter part makes an obtuse angle. CONSTITUTION:The inside diameter d1 at each of both ends of respective oil impregnated sintered bearings 71, 72 is made to be smaller than the inside diameter d2 at the axial central part. Since each of recesses 81a, 82a is formed in a circular-arc shape in its axial cross section, the part X (not shown) changing from the inner circumferential surface of the small diameter part d1 to the respective recessed parts 81a, 82a of the large diameter part d2 makes an obtuse angle. Thus, the damage of a shaft due to galling at the part X caused by the deflection of the shaft or the like can be prevented, and also the breakage of oil film at the part X on the inner circumferential surface from the small diameter part d1 to the large diameter part d2 can be prevented.
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