Apparatus for the level adjustment and/or arching adjustment of a flexibly resilient support element of a back rest of a seat

Apparatus for the level adjustment or arching adjustment of a flexibly resilient support element (4) for the lordosic vertebrae of a sitting person, and which is fitted in the frame (1) of a back rest of a seat said apparatus for level adjustment and/or arching adjustment comprising a gear mechanism (12) including a worm (14), a worm gear (15), a pinion (16) and a tooth element as well as a drive means, characterized in that the gear mechanism is directly connected to the drive means in such a manner that a rigid drive shaft (13) thereof carries the worm (14) engaging into the worm gear (15), the pinion (16) being fixed axially in the worm gear (15) in tooth engagement with a gear wheel (17) in a plane parallel to the worm gear (15), the gear wheel (17) being associated with at least one reel (21) to which one end of a sheathed cable (23) of a Bowden cable assembly (24) is fixed and onto which it can be wound, the gear wheel (17) comprising a web (34) which coacts with stop formations (35) inside a casing (11) of the gear mechanism (12) to limit in a defined manner the movement of the gear wheel (17);

• and
• a casing disposed in a plane between said worm gear and said gear wheel, and a first cover connected to said casing for covering said gear wheel and a second cover connected to said casing for covering said worm gear.