A locomotive or engine is a rail transport vehicle that provides the motive power for a train. 2011 relations. 2003 relations: A. Leslie and Company, Abilene and Smoky Valley Railroad, Acámbaro, Ace Trumps, Adams axle, Adhesive weight, Adirondack Scenic Railroad, Adler (locomotive), Adolph Giesl-Gieslingen, Advanced Train Control System, Agatha Christie: Murder on the Orient Express, Agecroft