| 摘要 |
<p>An adjustable height chair in which a height adjustment tube slides in a vertical cylindrical post. The post is provided with a plurality of spaced annular grooves and the tube is provided with a plurality of radially extending bores each containing a detent ball. A piston is provided to releasably lock the balls in the bores in engagement with a desired groove. Upon movement of the piston, the balls are released and slide under gravity towards the centre of the tube until they abut a collar on the piston. The bores slope diagonally downward from the periphery to facilitate the movement under gravity and to effect diametrically directed load transfer from the tube to the groove in the post.</p> |
