Solid-freight semitrailer with a fast freight loading and unloading system

The semitrailer (1) has a supporting frame (2) defined by longitudinal members (6, 7, 13) connected by cross members (15, 16); and a number of parallel conveyor belts (18). Each conveyor belt (18) is moved longitudinally by pairs of pulleys (19, 21) to define a flat portion of the path of the conveyor belt (18) for supporting freight during transportation; the pulleys (19, 21) and the conveyor belt (18) are arranged so that the flat portion of the path is on a level with the normal loading surface (P) of the semitrailer (1); the conveyor belt (18) has a supporting structure defined by a pair of further longitudinal members (23) connected by respective cross members (24) and fixed to two of the longitudinal members (6, 7, 13) of the frame (2); the pairs of pulleys (19, 21) are carried by shafts (36, 54) fitted to the pair of further longitudinal members (23) of the conveyor belt (18); and the conveyor belts (18) are located alongside fixed strips (77, 84) carried by the longitudinal members (6, 7, 13) of the frame (2) and on a level with the loading surface (P) of the semitrailer (1).