Kato 126-4014

Union Pacific “Big Boy” 4014 

One-time series only for Insider members

Model Features

• Locomotive type: 4-8-8-4 articulated steam locomotive
• Running number: 4014
• Livery: Union Pacific black, representing the modern excursion train appearance
• Drive: Two synchronised coreless motors with brass flywheels
• Lighting: Illuminated LED headlight
• Minimum curve radius: 282 mm (11 inches)
• Power system: Analogue DC
• Digital readiness: DCC-ready; decoder not included in this version
• Couplers: Kato knuckle couplers, with additional heavy couplers for double-heading
• Special features: Detailed piping, metal frame, additional weights and electrical pickup from both locomotive and tender
• Length: Approximately 250 mm

The Kato 126-4014 is a finely detailed N-scale model of the legendary Union Pacific Big Boy steam locomotive, restored to operation in 2019 and used for special excursion trains. It is designed for smooth running and strong pulling performance

History, Union Pacific Big Boy 4014

Union Pacific “Big Boy” 4014 – The World’s Largest Operating Steam Locomotive

One of the legendary Union Pacific “Big Boy” 4‑8‑8‑4 articulated steam locomotives, No. 4014 belongs to a class of 25 built by ALCO in the early 1940s to handle the heaviest mainline freight over steep mountain grades. Designed for immense tractive effort and sustained high power, the Big Boys could move long, heavy trains where smaller engines struggled — making them engineering icons of North American railroading.

UP 4014 is a fully restored 4-8-8-4 “Big Boy” steam locomotive, originally built in 1941 by the American Locomotive Company. Designed for hauling heavy freight through the Wasatch Mountains, it served the Union Pacific until 1961, after which it was placed on public display in California.

Reacquired by Union Pacific in 2013, No. 4014 underwent an extensive restoration at the UP Steam Shop in Cheyenne, Wyoming. In 2019, it ran under its own power for the first time in nearly 60 years—making it the largest operational steam locomotive in the world, and the only running Big Boy of the eight preserved.

Today, UP 4014 operates in special excursion service as part of the Union Pacific Heritage Fleet..

Key points

• Type: 4‑8‑8‑4 articulated steam locomotive (Big Boy)
• Builder: ALCO (early 1940s)
• Role: High‑power heavy freight over mountain grades; long‑haul mainline service
• Power & design: Massive boiler, articulated frame and large driving wheels for both traction and stability under load
• Service life: Intensive wartime and postwar freight duty through the steam era; retired with dieselisation in the 1950s–60s
• Legacy: Few examples survive in preservation; the Big Boy series remains an enduring symbol of American steam power and a must‑see for enthusiasts