Abstract: An automatic stabilizing unit for a free trolley and a load carriage in an inverted power and free conveyor system is connected to the free trolley. The stabilizing unit includes a stabilizer actuator which extends above a free track containing the free trolley from beneath the floor of a building which houses the conveyor, and a stabilizing gear mounted on the load carriage. At locations in an assembly plant, such as robotic welders or riveting stations where load shifting tolerances are critical, there must be additional stabilization of the load carriage. At these locations, stabilizing rails are positioned on top of the free track in line with stabilizing trucks on the stabilizing actuator. When the stabilizing trucks contact the rails, the trucks are urged upward, pushing an attached piston upward against a spring which causes a pair of stabilizing wheels on the stabilizing gear to rotate downward into contact with the factory floor, thus stabilizing the carriage only when needed.