4-8-8-4 — The Bigboy Survivors

What is a Bigboy? It is the largest successful steam locomotive class to be manufactured and run in any quantity.

The Bigboy is a type 4-8-8-4 locomotive, which means that it has 4 smaller wheels at the front to keep the engine on the tracks, 8 large driver wheels (68 inches in diameter), 8 more large driver wheels, and 4 smaller wheels to hold up the firebox at the back end of the engine. Even more remarkable, the Bigboy is “articulated”, which means that the front 12 wheels are mounted to a frame that pivots independently of the rest of the engine. This allows it to go around corners that are sharper than what a similar sized non-articulated engine could negotiate. The Bigboy is 132 feet 9-3/4 inches long and weighs 1,208,750 pounds. Fully loaded, it carries 28 tons of coal and 25,000 gallons of water.

A total of 25 Bigboys were built in the early 1940’s. They were purchased by the Union Pacific Railroad to pull a 3,600-ton train up Sherman Hill in the Wasatch mountains just east of Ogden, Utah. While the grade was less than 1% across Wyoming, Sherman Hill was 1.55%. That meant the need for helper engines which slowed traffic and increased operational costs. The Big Boy could do the job unassisted at mainline speeds. This was perfect for high priority express trains such as the Pacific Fruit Express. Each Big Boy accumulated over 1,000,000 miles before being retired between 1959 and 1962.

Click For Larger Photo
Bigboy line drawing by Larry Murchinson, used with permission (click to enlarge).

No Bigboy is currently in running condition. In the late 1990’s, #4018 was slated to be restored to run in a movie. She was actually moved around at the Age Of Steam Museum to put her in a position to be towed out for restoration. Fortunately, the project collapsed before the #4018 was moved out of the museum and tore down--the museum likely could not have afforded to put her back together and move her back to the museum. Even if a Bigboy is restored to operation, there is very little track in the US that can support its enormous weight.

Note—click on the Cab Number to see a photo of each Bigboy locomotive.