Prototype Information:
The 4-8-8-4 Big Boy is an articulated Steam Engine manufactured by the American Locomotive Company between 1941 and 1944. The Union Pacific was the sole purchaser of these engines, owning and operating a total of 25 of the colossal 600 ton engines. The 4-8-8-4 wheel arrangement combined stability and power, with the four wheel leading truck allowing for smoother entry into curves while the two sets of 8 drive wheels provided 135,375 lbf of tractive force. The trailing four axle truck helped support the large firebox that was needed to keep the massive engine fed. The original Big Boy engines were coal powered, with 4014 being converted to oil when it was rebuilt after its retirement to be used in excursions.
The Big Boys plied the rails as reliable workhorses until the final unit was retired from revenue service in 1959, with eight engines surviving today. While most of the survivors are static display pieces, unit 4014 was re-purchased in 2014 by the Union Pacific and rebuilt in a five year process that brought it back into service as the largest, most powerful operating steam locomotive in the world, touring in 2019 and again in 2021 to celebrate the history of America’s transcontinental railroads and the Union Pacific’s commitment to preserving its history.
Read more about UP 4014 on the UP Website: Click Here
