These locomotives were great...by far, the largest 12 coupled locomotive, and, excluding failures and one-offs, are the largest and longest rigid framed steam locomotives ever built! Here's two good site... [Link] & [Link] ...And some photos...
Pretty awesome loco! If I understand correctly (always a dicey proposition) these were used in Wyoming-Utah, and were well-regarded. They were also the forerunner of the Challengers, which essentially replaced the rigid frame with the articulated. Anybody to correct or confirm this?
I've sometimes heard that they were displaced from Wyoming to Nebraska by the Challengers and Big Boys, but I've seen photos of them still in Wyoming in the 50s. It is interesting that these, the final evolution of pre-superpower freight steam, lasted almost as long as their successors. The usual fate of steam of their generation, because the last generation was retired after such short lives.
How did they ever get these engines to negotiate a turn? They must have had some wiiiide radius turns.
Well, the first had no flanges on the 3rd and 4th axles, but afterward it was found out the the lateral motion devices and thin flanges were enough.
Yes, and I believe it is the only survivor of the class. 9000, the first one, in your photo, is displayed at the Pomona Fairgrounds near Los Angeles. The display site is maintained by a local chapter of the Locomotive and Railroad Preservation Society and the last time I visited, many years ago, it was only open about every other weekend. A very interesting site, displaying UP Big Boy 4014, UP 9000, UP Centennial diesel 6915, Santa Fe Hudson 3450, SP 4-10-2 5021 and a few smaller engines. 9000 and 5021 are both three cylinder engines with Gresley valve gear on the pilot controlling the third cylinder. Since they are pretty much locked down in static display you can crawl under and see how that third cylinder drove a giant crank in the second axle. Very worthwhile to visit there. :tb-biggrin:
A question: I am not modeling steam, so I am not real savvy on these points. However, I am a mechanic and have a problem understanding "lateral motion" on fewer than all of the wheels at once being that they are all tied together with the drivers. Surely the drivers didn't flex. If I get into this mechanical aspect of steam, I may have to make a transition. Any machine that has mass and a million parts fascinates me.
Alco's lateral motion devices were on the first and sixth axles, which allowed them to move up to two inches.
I found this photo of one of the three cylinder 4-10-2s at Cajon Pass on the Library of Congress web site. You have to zoom in a lot but can make out the number 5098 on the cab. That jibs well with the numbers assigned to the Los Angeles & Salt Lake subsidiary of the UP. Not quite a big as the 4-12-2s but still monsters. Mikado 2790 is behind it in helper service on a refer train in 1943.
