02165. Big Boy Locomotive

The American Big Boys are among the longest and largest production steam locomotives ever built in the world. During the late 1930s, Union Pacific often used auxiliary locomotives to pull trains from Ogden, Utah to Wasatch over a steep pass. U.P. wanted to simplify this system and commissioned its own engineering department to design a new locomotive that could pull a 3,600 ton train (up to a maximum of 4,200 tons) up the steep pass. The 25 Big Boy locomotives were built in 2 groups. The first group, called class 1, was built starting in 1941. The second group (class 2) was built in 1944. The last freight train transport handled by a Big Boy locomotive was in July 1959. Most of the Big Boy were taken out of service in 1961.