| 摘要 |
A wheel comprising (i) an axle secured to a movable body, (ii) a rotator journaled on the axle so as to be freely rotatable and having at least three apexes disposed rotationally symmetrically around the axle, and (iii) rollers, each roller being mounted on one of the apexes of the rotator so as to be freely rotatable. Each side between apexes of the rotator is provided with a guiding surface which has small frictional resistance and is slidable.
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