N Big Boy Wilson Aftercooler, Paragon 4 Unlettered

Broadway Limited Imports

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N Big Boy Wilson Aftercooler, Paragon 4 Unlettered

Often called the largest steam loco ever made, and certainly a contender for the Worlds Most Famous Locomotive, the Big Boy was forged under some of the most strenuous demands ever placed on a locomotive.


The UP Railroad needed a locomotive that could be used to pull a 3,600-ton train over Sherman Hill and the 1.14% grade from Ogden to Wasatch, Utah without the need for helpers.

When the design specifications were complete, it was decided on the use of a simple articulated, high speed, 132 ft. long locomotive sporting sixteen 68 diameter drive wheels. What they created was the longest and among the heaviest, most powerful steam locomotive legends in the world. And had not the worker at ALCO chalked Big Boy on the side of the smoke box of one of the 4-8-8-4s under construction, a name that immediately caught on, it is rumored that the name of the type would have been Wasatch, for the mountains they were built to conquer.

There were 25 locomotives fabricated in two different groups. Class 1 were locomotives #4000-4019 and Class 2 was numbered 4020-4024. The first Big Boy #4000 was delivered to Omaha, NE on September 5, 1941. The Union Pacific Railroad's commitment to the Big Boy required them to replace the lighter rail and straighten out many miles of track for clearance as well as to resize elements of their service areas (such as turntable lengths, etc.) for the entire line these locos would run on.

The Big Boys demonstrated fantastic strength and speed as they faced these challenges throughout their storied careers. With the total mileage on the Big Boy fleet being approximately 1,000,000 miles for each locomotive, one must say that they earned their reputation.

Several examples remain in museums around the country but silently they sit as a visual echo to the thunder that once made them revered throughout the landscape that the Big Boys dominated.


  • Paragon4 Sound and Control System featuring ROLLING THUNDER

  • Integral Dual-Mode Decoder with Back EMF for Superb Slow Speed Operation in DC and DCC

  • Precision Drive Mechanism Engineered for Heavy Towing and Smooth Slow Speed Operation

  • Operating Smoke Unit with On/Off Switch

  • Six Drivers and All Tender Wheels Pick-up Electricity from Track

  • Die Cast Locomotive Body with Die Cast Chassis for Heavier Weight and Maximum Tractive Effort

  • Will Operate on Code 55, Code 70, and Code 80 Rail

  • Rubber Tires on Two Drivers for Additional Tractive Effort

  • Premium Caliber Painting

  • Prototypically Accurate Paint Schemes and Road Numbers

  • Many Separately Applied Details such as Handrails, Grab Irons, Piping, Tender Ladders, Whistle, and Bell

  • Prototypical Headlight and Rear Light Operation

  • Separately Controllable Cab Light

  • Prototypically Accurate Sounds for the Union Pacific Big Boy

  • Operating Microtrains-compatible Couplers

  • Minimum Operating Radius: 9.75 inches


In the first production of this model in N scale, BLI is modeling the Union Pacific Big Boy with these notable features such as, accurately modeled front end with appropriate aftercooler system for each class, accurately modeled 25-C-100 and 25-C-400 tender, appropriate for each class, accurately modeled oil tender for #4014 which operates in excursion service today, and two models painted in attractive two-tone gray paint schemes that the Big Boys never received in real life.

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