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Union Pacific Big Boy 4-8-8-4


The prototype

Well just about anybody who knows a little something about railways knows the Big Boy. So what do I need to say more? Well, that it was not the largest steam locomotive in the world!! May be the longest, but not the heaviest and neither the strongest. On both these dimensions the Big Boy was surpassed by the Allegheny. Yet somehow these is the most appealing model of the giant American articulateds. And fair is fair: they are impressive!!

The 25 Big Boys were built in two groups. The first group, numbered 4000-4019, was built starting in 1941. The second group, numbered 4020-4024 was built in 1944. There main domain was at Sherman hill between Cheyenne and Laramie Wyoming. The last revenue freight pulled by a Big Boy was in 1959. Most were retired until 1962. There are no operational Big Boys at this moment. Initiatives to restore one to operational condition have failed so far.

Lots of photo's

Note: locomotives like the Big Boy are often referred to as Mallets. Strictly speaking this is not the case. These locomotives are articulated conform the Mallet system. They do not use compound expansion however, which explicitly was part of the Mallet patent, and both sets of cylinders are fed with live steam directly from the boiler.

The model

Well guess. What is it? Märklin? Lionel? Life like? Bowser? Nope. None of these. Revell. It is a static all plastic model of only 18 euro. Yes, if you take a close look you can see it. But the difference with my Challenger from Rivarossi isn't that much. I will buy a proper Big Boy one day but it should do very much better then Rivarossi's Challenger

Building this model was fun. It does not require a lot of tooling like brass or white metal models do. Detailing this Big Boy requires patience though. The handrails along the boiler are cast on the boiler and are terribly ugly. Cutting them away needs quite some time. I made new handrails from 0,5 mm brass wire. The stanchions were made of wire too, which I flattened with a file to a D-shape, bent around the rails and then soldered to fix it.

The leading set of drivers is mounted correctly to the frame: it swivels from a turning point between the rear set of cylinders. If you build this model to the letter of the enclosed leaflets you will find however that the first set of wheels will not swivel at all. This is caused by the steam pipes which feed the fresh steam from the boiler to the front cylinders. They should be extendible but they are not. I cut the steam pipes in two, glued a short brass tube on one half and thoroughly sanded the other half to fit in the brass tube. This way it could slide in the brass tube, thus allowing the steam pipes to shorten or lengthen as the movement of truck required. Is it of much use? Very little, the model does not run. But putting the Big Boy in a curve shows the principle of the mallet configuration magnificently


This model was was crushed beyond repair in the collapse of my bookshelves in the summer of 2006. Being the uppermost model in my display cabinet it took the full blow of 80 kilos of books coming down.
Among the Big Boy two other models were seriously damaged: the NS7851 and the BRB. The BRB, though heavily damaged, can be rebuild. The NS7851 is set aside for later inspection but is very likely a total loss.
The Shay was also involved but damage was limited, though painful because I had only recently completed the project. I wil repair it when I find the courage to restart a finished project.
Thankfully other models like my Climax and Y3 went out without a scratch.