Installation for assembling several car body models of the same type of motor veicle

Apparatus for positioning and holding car body parts and for welding these parts to one another, comprising a fixed, rigid supporting stand (1) having an upper part with a horizontal conveyor track (11) and at least two upper carriages (13, 14), each having positioning and holding devices for components of the upper part of different car body models of a motor vehicle;

• said supporting stand having a lower part with a lift (8, 10) positioned over a pit and carrying centering devices cooperating with the components of the lower part of a type of car body for a motor vehicle, which car body lower part is common to several models, said lift being disposed between horizontal transfer tracks arranged in alignment and each abutting the base of said stand, and said lift being displaceable between two positions, namely a lower position in which the lift is situated between and in alignment with said transfer tracks (3, 4) one of which tracks (3) is for bringing to said stand car bodies to be welded and the other of which tracks (4) is for removing from said stand car bodies which have been welded and an upper position, in which the car body of a model of vehicle engages with the positioning and holding devices (13.sub.1, 14.sub.1) for one of the corresponding models of vehicles, supported by one of the upper carriages (13, 14).