Abstract: A chair wherein the support at the upper end of the leg has a rigidly mounted carrier for the front portion of the seat and a carrier for the back rest. The carrier for the back rest is connected to the carrier for the seat by a coupling which allows angular and translatory movements of the carrier for the back rest. A detent mechanism is provided to hold the back rest in any one of several different positions of inclination with reference to the seat. One element of the detent mechanism is a toothed rack on a slide which is connected with the carrier for the back rest and is reciprocable in a slot of the carrier for the seat. Another element of the detent mechanism is a lever which has one or more teeth movable into and from mesh with the teeth of the rack by a mechanism which can pivot the lever against the opposition of a torsion spring.

Abstract: A chair has an adjustable seat or back rest which is connected with an air spring. The air spring has an engaged condition in which the seat or back rest is locked, and a disengaged condition in which the seat or back rest may be adjusted as desired. A pivotable handle located beneath the seat permits a user to change the condition of the air spring. The handle is connected with a first shaft which carries a first coupling element. A second shaft carries a cooperating second coupling element and acts on an actuating rod of the air spring to change the condition of the latter in response to manipulation of the handle. The shafts are relatively rotatable, and the coupling elements define a gap permitting rotation of one coupling element relative to the other through a distance equalling the length of the working stroke of the actuating rod. In the engaged condition of the air spring, each coupling element is held in a respective end position by a biasing force. The handle is in a lower terminal position.