The locomotive crane is similar in general construction to the steam shovel. A locomotive crane consists of a welded steel car body, rotating machine house, lattice boom and two sets of trucks designed to run on railroad track. The major components include a diesel engine, generator, traction motors, axles and various mechanical and hydraulic systems and controls. These cranes have a lifting capacity ranging from 25 to 250 tons depending of their size and how they are equipped. A unique feature of locomotive cranes is their ability to perform lifting operations while serving as a locomotive for one or more attached rail cars.