Height adjustment device, particularly for the seat back portion and arm-rests in office chairs

Abstract

A height adjustment device, in particular for seat back portions and arm-rests in office chairs, comprising a guide element (14, 48) rigid with the support plate (10) for the seating portion (12), a slide (22, 42) supporting the movable part (18, 20) and engagable with and slidable along said guide element, and means (38) selectively engagable in one of a plurality of teeth (31) to provide a configuration of stability, said selectively engagable means sliding freely along the passive flanks of the teeth of the toothed portion during the raising of the movable part, and lockable by the active flanks each time a tooth is passed over, said selectively engagable means being disengagable, for a predetermined position of said slide (22, 42) relative to said guide element (14, 48), from said teeth thus enabling said slide to move by gravity along said guide element, characterized in that said toothed portion (28) is faced by a toothed counter-portion (32) the teeth (34) of which form with the teeth (31) of said toothed portion (28) a mixed-line channel, the roots (30, 33) of the teeth (31, 34) of said toothed portion (28) and counter-toothed portion (32) forming respectively the seat of stable configuration and of temporary obstacle to the movement of said selectively engagable means along the mixed-line channel.

Dependencies are inferred from the claim text.