| 摘要 |
A motor of long life and high precision in its rotation wherein the variation on the rotation and the noises generated thereby are suppressed by maintaining the radial clearance between the components of the bearing device constantly in an appropriate value even if the thermal expansion of the components is caused by rising the temperature thereof. A motor having a rotational member supported rotatably through a bearing device provided on a base member of the motor, said bearing device comprising upper and lower ball bearings each of which includes an inner ring fit around a shaft of the motor, an outer ring, and a plurality of balls interposed therebetween, said bearing device further comprising a spacer interposed between the outer rings of the upper and lower ball bearings wherein the spacer is made of material larger in its coefficient of linear expansion than that of the upper and lower outer rings.
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