Built by the American Locomotive Company (ALCO) in Schenectady, New York, in November 1941, 4012 was one of just 25 Big Boy locomotives constructed for the Union Pacific Railroad. These enormous 4-8-8-4 articulated steam engines were designed for one important job: moving extremely heavy freight trains over the steep grades of the Wasatch Mountains in Utah and Sherman Hill in Wyoming. At roughly 1.2 million pounds and more than 132 feet long with its tender, Big Boy 4012 was an incredible example of early twentieth-century engineering. Its sixteen 68-inch driving wheels and four cylinders produced enormous pulling power, allowing a Big Boy to handle trains that would have required several smaller locomotives.
This Big Boy was on display at Steamtown Historical Site in Scranton, Pennsylvania.
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