Transportation system

A transportation system comprising a continuous stationary track having a pair of opposed rigid bearing surfaces, and a plurality of discrete cantilevered load-carrying vehicle units movable beside said track, each said vehicle unit being coupled to said track by means of a bogie having a linear arrangement of bogie wheels running between said bearing surfaces, characterized in that said bogie wheels are mounted on mutually articulated frames and have a diameter slightly less than the separation of said opposed bearing surfaces to allow limited pivoting movement of said frames within said track, and urging means for forcibly urging adjacent articulated frames to pivot in opposite directions within said track between said bearing surfaces such that bogie wheels carried thereby forcibly and alternately engage said respective opposed bearing surfaces at at least three points to ensure a pre-loaded positive coupling between said bogie and said track.