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.
Kato’s N scale Big Boy engine is a wholly new and unique design from any steam engine that has come before, utilizing two coreless motors in dual articulated metal mechanisms to power the 16 total driving wheels. Thanks to the articulated design just like the real engine, the two sets of driving wheels are able to move independently which gives the engine the ability to navigate 11″ radius curves, allowing the locomotive to run with Kato’s other large scale engines like the FEF-3 and GS-4. The engine also features pickup both from the drive sections as well as the tender for maximum electrical coverage and reliability, and will be fully ready to run no matter which variation you purchase with all details fit and ready to go out of the box, options for pre-installed DCC and even DCC + Sound, and operational lighting from the deck mounted forward facing headlight.
- Dual coreless motors with brass flywheels for unmatched pulling performance
- Weights carefully placed along the body even in the cylinders to give the engine perfect balance and weight distribution.
- Minimum radius 11″ (282mm)
- Operational tinted LED headlight
- 4014 has the iconic “Big Boy” chalk lettering on the front of the smokebox
- 4014 is built to match the 2021 Excursion tour appearance:
– Oil Tender
– Graphite Firebox
– Silver cylinder head and piston covers
– Builder’s Plate