An overhead monorail conveyor whose inverted U-shaped rail has flanges provided with inwardly extending lower marginal portions to provide tracks for the wheels of a vehicle having an inverted U-shaped frame which surrounds a portion of the rail. The wheels are mounted on brackets which extend at a level below the marginal portions of the flanges and thereupon upwardly into the interior of the vehicle frame. The motor which drives the vehicle is mounted in the frame in the interior of the rail, the same as the conductors which supply electrical energy and the toothed rack or racks which mate with several gears driven by the motor. The interior of the rail further confines and shields other sensitive components of the conveyor, such as electric switches, proximity detectors, contacts which slide along bus bars, centering rolls for the frame of the vehicle, and devices for biasing the motor-driven gears against the toothed racks.