1. A transport system comprising: a fixed rail track erected along a transporting route having branching routes, said track having a vertical surface and an inclined surface inclined with respect to said vertical surface at each of a top portion and a bottom portion of the track vertical surface; a plurality of linear motor driven transport vehicles for moving along said rail track; a plurality of linear motor units disposed at set intervals along the length of said rail track, all along one side of said rail track, and between said vertical surface top portion and said bottom portion, each said linear motor unit including a primary drive unit; a housing covering said primary drive unit, said housing also covering control devices including a solid state relay and a speed sensor and at least one terminal block to control electrical current supplied to a motor coil of said primary drive unit, and a shielding plate between said speed sensor and said motor coil; attachment devices for attaching said housing covering the primary drive unit and said control devices; each of said plurality of transport vehicles having a secondary drive unit for the linear motor, a first pair of rollers on a top portion of each of said plurality of transport vehicles, one roller of said first pair to rotate against a top portion of the track vertical surface and the other roller of said first pair to rotate against said inclined surface of said vertical surface top portion, said first pair of rollers mounted to swivel about a vertical axis; and a second pair of rollers attached to a bottom portion of each of said plurality of transport vehicles, one roller of said second pair to rotate against a bottom portion of the track vertical surface and the other roller of said second pair to rotate against said inclined surface of said vertical surface bottom portion; a spring acting against said roller of said second pair engaging the inclined surface mounted to swing over a predetermined range of angles about a fulcrum provided at a predetermined point, so as to press against said bottom inclined surface by the force provided by said spring.