sentences:  In 1926, Fruehauf introduced the automatic semi-trailer in which the coupling and the uncoupling of the tractor were accomplished mechanically by the motion of the tractor.Fruehauf's introduction of the automatic semi-trailer was instantly recognized by transportation experts as a major contribution to the industry.The automatic semi-trailer coupling patented by Fruehauf dominated the semi-trailer market until the Fruehauf Trailer Corporation's assets were sold in bankruptcy to Wabash National in 1997.