| 摘要 |
<p>HEIGHT ADJUSTABLE CHAIR BASE A rotatable and vertically adjustable chair base is disclosed comprising a floor engaging stand, an up standing tubular post mounted on the stand, a threaded member received by the tubular post and a smooth spindle slidably and rotatably received by the upstanding tubular post. Internal threads are provided in the upstanding tubular post with a split sheet metal sleeve carrying stamped metal threads. The stamped metal threads of the sheet metal sleeve are engaged by a plastic threaded member which takes advantage of the relatively low coefficient of friction between plastic and metal. The spindle rides atop the threaded member, the vertical position of the spindle being determined by the position of the threaded member. Vertical adjustment of the spindle and the chair mounted atop the spindle is achieved with detent means for alternately engaging and disengaging the threaded member. When the chair is unoccupied, the spindle engages the threaded member and is vertically adjustable by rotation of the chair. Under the weight of an occupant the spindle automatically disengages from the threaded member to allow the occupied chair to freely rotate without vertical adjustment of the spindle.</p> |
