An articulated locomotive is a steam locomotive with one or more engine units that can move independently of the main frame. Articulation allows the operation of locomotives that would otherwise be to
Side profile shot of Big Boy no. 4014, an articulated simple expansion steam locomotive
The Union Pacific Big Boy is a type of simple articulated 4-8-8-4 steam locomotive manufactured by the American Locomotive Company in Schenectady New York between 1941 and 1944 and operated by the Uni
Publicity photo of Union Pacific Big Boy No. 4000, the first of the class, taken in 1941
The cab controls of No. 4005 at the Forney Transportation Museum in Denver, Colorado
A close-up of a Hancock long-bell 3-chime "steamboat" whistle used on No. 4017
Union Pacific 4019 hauls a train through Echo Canyon, Utah