Abstract: A wheelchair has two central wheels that can be separately driven by a motor. In order to allow the wheelchair to turn around in narrow spaces, the central wheels can be driven in opposite directions of rotation. When the wheelchair is turned around, the front wheels and rear wheels do not constitute a hindrance because they are kept at a distance from the ground by the swiveling wheel. All three wheels are coupled together on each side by a chain. When the front wheels run against an obstacle, the wheelchair climbs over the obstacle with the driven front wheels. This causes the fork of the swiveling wheel to swivel about the rotational axis in the direction of arrow, against the force of a spring, bringing the rear wheels in contact with the ground and also driving the wheelchair's rear wheels. This all-wheel drive allows the wheelchair to overcome relatively high obstacles both forwards and backwards, even when driving slowly and without losing its maneuverability.

Abstract: The seat back unit has a seat back frame which can be tilted around the tilting axis (11) of the support (21). Movable on the seat back frame (13) is the seat back (25). A linear motor (33) serves to incline the seat back frame (13) together with the seat back (25). With a linear motor (33) the distance between the support (21) and the connecting section (17) of the back frame (13) can be reduced or increased, respectively. A tape (43) extends from a stationary part (45) of the linear motor (33) via the connecting section (17) to the seat back carrier (44). Accordingly, if the seat back frame (13) is tilted towards the rear, the seat back (25) is moved downward together with the arm rests (29) attached to the seat back carrier (44). A stabilizing mechanism (51) keeps the arm rest (29) in a practically horizontal position. Accordingly, on reclining the arms of the user remain always in a practically horizontal position and are finally lowered to a position practically parallel to the body.

Abstract: An inclinable seat arrangement, in particular for a sick or handicapped occupant, is described. It comprises a framework (2) and an inclinable seat (3) connected to the framework by an articulation (4) and by a positioning mechanism arranged so as to facilitate the manipulations for inclining the seat by the occupant or by another person. The axis of the articulation (4) is preferably located proximate a vertical line passing through the center of gravity (G1) of the occupant when in a position corresponding to the equilibrium position of the empty seat. An elastic mechanism, exerting a progressive return couple toward the equilibrium position, comprises elastic bearings (24) within the articulation. The elastic mechanism also preferably comprises a constant force gas thrustor (6) which includes a controlled blocking arrangement. In place of the gas thrustor there may be provided a motorized jack (51) controlled by the occupant (48).