| 摘要 |
A controlling device for a support pivotally mounted on top of a stool includes a housing adapted to securely engage with a bottom face of the support, two pawls pivotally received in the housing, a wedge and control knob connected to the wedge and a ratchet gear received in the housing. After either one of the pawls is activated, the activated pawl is able to selectively engage with the ratchet gear so that the support is able to pivot in a predetermined direction.
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