and you thought restoring a plane was hard

[airnutz]

Well, I reckon that would make the Big Boys the largest in the world now...woonit?

[quemerford]

Well no. Largest surviving, but not largest.

[airnutz]

Well no. Largest surviving, but not largest.

Just making the point, I haven't heard anyone making the claim, "largest ever built" but rather "largest in the world".

[CAPFlyer]

Its the largest of the steam locomotives.

Often quoted but I'm not sure it's quite correct; Baldwin made an XA Triplex with a 2-8-8-8-4 wheel arrangement and also the Erie Class P-1 was a 2-8-8-8-2. My late father (a massive UP and Big Boy fan) made a point of stating that others were larger, though maybe not so heavy. Still an awesome piece of kit.

The Baldwin Triplex locomotives, while having more drivers, was not actually larger than the Big Boys. The reason for the design was for pulling in the mountainous coal regions and thus tractive effort and the ability to make tight curves was the need, not size. Both the 3 units for the Erie railroad (2-8-8-8-2) and 1 for the Virginian (2-8-8-8-4) only lasted a couple of years and none ever made their design parameters. The biggest problem beyond the fact they could not generate sufficient steam to power themselves beyond about 5 mph, was that the tractive effort regularly exceeded what the couplers between the locomotives and the train could handle, causing even more problems and delays.

Additionally, beyond size, the Triplex locomotives came in under 1.2 million pounds while the Big Boys were/are about 100,000 pounds heavier.