Tractor semi-trailers of the new generation PST-18 is unified semi-trailer of increased carrying capacity on wide-profile tires for tractors "BELARUS" of traction classes 2-5. The main all-metal body with a tailgate opening with the help of hydraulic cylinders has a capacity designed for transportation of materials of medium density (land, garbage, manure, ready silo, mineral fertilizers) taking into account the natural bulk cone (cap). By request, for transportation of seeds of various crops, root and field crops, compound feed, semi-trailers are equipped with low added boards, and for lightweight goods with high added boards.