Big Boy – a steam locomotive from the Rocky Mountains

4000 class locomotive of the Union Pacific Railroad literally stunned the workers who assembled it at the ALCO plant (USA) with its unprecedented dimensions and power. One of them wrote “Big Boy” in chalk on the first locomotive of this series. It was in 1941.

steam locomotive

Under this name everyone remembered the longest (40.47 meters) and the heaviest (548.3 tons) serial steam locomotive in history. With a capacity of 6300 hp, he was able to carry trains weighing up to 3.5 thousand tons, though not faster than 70 km/h.

However, the Big Boy never achieved wide popularity over the years of its operation (1941-1959): all 25 locomotives of this series carried heavy trains along the Union Pacific line through the Wasatch mountain range (Rocky Mountains). Today, eight “Big Boys” have survived, all of them adorn railway museums. One has a chance to get back on track and carry tourist trains. Restoration work began in 2013 in California.


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Railway magazine “Railway Supply”