Union Pacific Big Boy
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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
4-6-6-4
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In the Whyte notation for classifying steam locomotives by wheel arrangement, a 4-6-6-4 is a railroad steam locomotive that has four leading wheels followed by two sets of six coupled driving wheels a
Union Pacific Challenger No. 3985 is an example of a 4-6-6-4 locomotive