The American Locomotive Co. in Schenectady, N.Y., built 25 of the monsters to Union Pacific’s specifications between 1941 and 1944, and they became legendary. They were the largest steam locomotives ever to work the rugged terrain of the American West, and by most standards the largest anywhere in the world, said Gordon McCulloh, a meticulous historian of Union Pacific steam power.
Read: Huge Big Boy Steam Locomotive Coming Back to Life
Big Boys are 132 feet long, including the tender, which carried coal and water. They weigh 1.2 million pounds with a full load of fuel. They are essentially two engines under one boiler, with two sets of eight drive wheels, each set powered by two enormous cylinders nearly 2 feet across.
In this Jan. 26, 2014 file photo, spectators view the historic locomotive, Union Pacific Big Boy No. 4014 at Metrolink Station, in Covina, Calif. The locomotive was to head for Colton over the next several weeks before No. 4014 is towed to Union Pacific’s Heritage Fleet Operations headquarters in Cheyenne, Wyo. (AP Photo/Ringo H.W. Chiu, file)
Workers wrote “Big Boy” on the front to commemorate the story of how the locomotive got its name, from an anonymous worker who chalked the words on one of the engines at the factory. (AP Photo/Ringo H.W. Chiu, file)
In this March 14, 2014 photo, Ed Dickens Jr., senior manager of heritage operations for the Union Pacific Railroad, describes maintenance work on Union Pacific No. 844, a restored steam locomotive, at the railroad’s steam shop in Cheyenne, Wyo. Dickens will oversee the restoration of another locomotive, Union Pacific Big Boy 4014, one of the largest steam locomotives ever built. (AP Photo/Dan Elliott)
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