Celebrate the pinnacle of steam engineering with the Mould King Big Boy 4-8-8-4 Steam Locomotive, a massive 1,040 mm (40.9 in) brick-built recreation of the most powerful steam engine ever built — the legendary Union Pacific Big Boy.
Developed by ALCO for the Union Pacific Railroad, only 25 of these giants were ever produced, designed to haul heavy freight across the rugged Rocky Mountains during the golden age of American railroading.
Constructed from 3040 premium-quality pieces, this model faithfully captures the Big Boy’s distinctive articulated chassis — with its 4-8-8-4 wheel configuration, long boiler, and rear tender in striking black and yellow “Union Pacific” livery. The intricate undercarriage features linked drive wheels and pivoting bogies that replicate realistic motion on track displays.
Inside the cab, you’ll find detailed gauges, pressure dials, valves, and levers, all rendered with mechanical precision. The boiler section’s removable top reveals inner steam pipework for both display and educational insight. The tender car features an openable coal compartment and the iconic “FIRE HOSE ONLY” markings, adding authentic industrial realism.
With its monumental scale, lifelike mechanical structure, and historical accuracy, the Mould King Big Boy stands as a tribute to the might and craftsmanship of early 20th-century rail power — a must-have centerpiece for advanced builders and collectors alike.
Key Features:
3,040 pcs
Over 1 meter long
Black locomotive body with yellow UNION PACIFIC tender
Authentic 4-8-8-4 articulated wheel system
Linked piston drive and turning wheel assemblies
Realistic coupler connection between locomotive and tender
Detailed gauges, pressure meters, and valves
Removable boiler top for visible internal piping structure
Marked “UNION PACIFIC” with open coal bay and external detailing
Yellow industrial finish with “FIRE HOSE ONLY” decal
Building Instruction Booklet Included