MEANS FOR ADJUSTING THE VERTICAL HEIGHT OF THE SEAT OF A CHAIR

This invention relates to a collet assembly for adjusting the height of a seat supported by a threaded seat-support spindle. The collet assembly comprises a resilient threaded collet sleeve having slits extending from the base of its threaded core to form resilient jaws and a bell surrounding the core. The assembly also includes a collet jaw seat having an internal tapered jaw seating surface supporting inwardly directed projections. The collet sleeve is threaded to the spindle and the jaw seat is pushed onto the spindle below the collet sleeve so that the jaws of the sleeve rest against the seating surface of the collet jaw seat and the projections on the seating surface project into the slits of the collet sleeve to prevent relative rotation between the sleeve and jaw seat. When the seat is unloaded the bell of the collet sleeve may be grasped by an operator to permit the spindle to be rotated with respect to the bell.