| 摘要 |
PROBLEM TO BE SOLVED: To prevent the tilting of a chair by forming dead centers in a front link mechanism and rear link mechanism, respectively, so that the rotation force, even if added to any one a front support and a rear support, is not transmitted to a base shaft. SOLUTION: A base unit 3 is set on a stepped floor 2, a base shaft KJ is rotatably supported on the base unit 3, and dead centers are formed in a front link mechanism 101 for converting the rotation of the base shaft KJ to the rotating motion of a front support 5 and a rear link mechanism 102 for converting the rotation of the base shaft KJ to the rotating motion of a rear support 6, respectively. According to this, even if a rotating force is added to any one of the front support 5 and the rear support 6, the rotating force is never transmitted to the base shaft KJ. When a plurality of chairs are raised and fallen at once, thus, the other chair interlocking with these chairs can be prevented from tilting.
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