Truck, trailer or semitrailer, having a back foldable side wall

The truck or semi-trailer or truck trailer (1) has a superstructure (2), where the roof surfaces (4a,4b) can be moved to the side by at least one hydraulic cylinder (10,11). When folded out, the hydraulic cylinder(s) lie(s) outwards on the roof surfaces between the stiffener ribs (19), while the extended floor surfaces (3a,3b) are supported on stands.