Pennsylvania 2-10-10-4 mallet articulated

As another reply indicated, the PRR never had triplexes or 2-10-10-4's.

There were only 4 triplexes in the US: three 2-8-8-8-2's for the Erie and a lone 2-8-8-8-4 for the Virginian. Both locomotives have been available as HO brass imports.

To my knowledge, no US railroad ever had a 2-10-10-4. The 4-wheel trailing truck was usually associated with high horsepower "Super Power" locomotive types developed in the later 1920's for higher speed freight and passenger service. I believe the only 2-10-10-2 types were 10 locos built new for the Virginian in 1918, plus a home-made rebuild on the ATSF from older

2-10-2's. The 2-10-10-2 was a slow, drag freight locomotive, the very antithesis of Super Power, so it would have been unlikely that a 2-10-10-4 ever made it to the drawing board. Both the ATSF and Virginian 2-10-10-2's were available in HO brass.

(And to avoid comments, the Virginian triplex is not an exception to my Super Power comment - the 4 wheel trailing truck was not used to support a large fire box as on Super Power designs, but was under the tender, and was thus more analogous to the 4 wheel truck used on centipede tenders.) Gary Q

The only ten coupled mallet articulateds in NA were several 2-10+10-2 types each for the AT&SF (that were not successful), and several more (larger) for the VGN (that were successful). I'm not a Santa Fe expert by any means, but I think the AT&SF engines were broken up into more conventional 2-10-2 types.

The only three-engined articulateds for NA were the four 'Triplex' types. Erie had three 2-8+8+8-2 types that were semi successful, and VGN had one 2-8+8+8-4 that was not successful. The VGN engine was soon broken up into a more conventional 2-8+8-0 and a separate 2-8-2 loco. Both were then around for many years. The failure of the VGN 'Triplex' lead to the development of the monstrous 'AE' class 2-10+10-2's mentioned above, that solved their need for a very powerful slow speed loco to move coal through the mountains.

Dan Mitchell ==========

Dale Kramer wrote:

The SF engines were rather interesting locos for several reasons. First is that the frames came from a bunch of 2-10-2 locos. Second is that the boilers had a pleated section in the middle above the kingpin to the front engine and the front half of the boiler sat on the front engine. The pleats had problems with clinkers getting into the pleating and breaking it up. The front part of the "boiler" was actually a preheater for the water. After the locos were broken up, they all became 2-10-2 locos again. Another of the SantaFe's stupid tricks dept. trying to make something decent better and getting so much wrong that it was silly.

-- Bob May Losing weight is easy! If you ever want to lose weight, eat and drink less. Works evevery time it is tried!

You answered your own question. These were never built.

Brian

Me too, will they work with 15" snap track?

Belongs right in there with the giant two-engined (left and right sides) four-trucked Shay proposed for the UP (drawings exist). And the two C-trucked (6-axle) Willamette. And a bunch of proposed turbines, etc. Fun to think about, or even to model as "what ifs". Also, remeber the 'humbug' cab forward Erie articulated that was making the rounds here a year or so back?

Fun, fun, fun!

Dan Mitchell ==========

H richards>

Yup, AT&SF tried several different 'flexible' boilered locos. Some had the 'bellows' joint and some had a 'ball and socket' joint. None worked worth beans.

GN also took a 2-8-0 and added a 2-6-0 front end in similar fashion. IIRC, #2000, a 'one of a kind'. Made a 2-6-8-0 out of it, with the forward boiler section (NOT flexible in this case) also just a preheater stage. The two boilers were internally separate, with a sort of central 'smokebox' between the two sections. It was NOT a success, and was later returned to two separate locos. The later fleet of GN 2-6-8-0's class M's were of conventional design.

Dan Mitchell ==========

Bob May wrote:

well by rough calculation one of these in n scale would be 8.855 inches long now that quintaplex that bad boy would be almost 11.5 inches long again in n scale. hmmm wonder if i could get it to go on my 12" curves ???

Of course it would - you might need a bigger hammer however.

Well, it MIGHT work if you used the 'flexible' (jointed) boilers tried by the AT&SF. Then the steamer would be almost like a string of F-units.

Dan Mitchell ==========

Gregory Procter wrote:

Conceptual drawings (from Lima) exist, and have been published in some of the better Shay books ("Titan of the Timber" for one, IIRC). It never got beyond the 'paper' stage.

The loco had just one frame, sitting on two span bolsters, each sitting on two two axle trucks. Thus four trucks under one frame. Think of it as steam powered loco similar in arrangement to the earlier UP gas-turbines. The two front trucks were to be driven by one 3-cylinder engine (like those on the WM 150 ton loco) on one side, and the two rear trucks driven by an identical engine on the OTHER side. Power would thus be about double that of the WM #6. The boiler was on center, unlike most Shays (except for Henry Ford's). The thing was huge, probably at least

250 tons (I can't recall the exact numbers without doing some research).

Anyway, it was LOT different that the several 4-truckers that were actually built, which were just enlarged 3-truckers, and otherwise conventional.

Dan Mitchell ==========

Dale Kramer wrote:

Something like a Garrett, then, except the overall frame was rigid?

\Brian

Not really. The Shay's boiler weight would have been carried directly on the span bolsters. Garratts don't have span bolsters, and are articulated in three sections. The Shay only had one real frame, and was NOT flexible in that regard (though the trucks and span bolsters could swivel beneath it). As I stated, the articulation was much like the four truck UP turbines, or some of the big two-engined Diesels like the U-50B's.

Dan Mitchell ==========

Brian Paul Ehni wrote:

Piggyback....

The whole point of a Garratt was that there was no overall frame to be rigid. The whole thing was flexible: two locomotive units with a boiler/cab slung between them. This allowed the optimum boiler design

- short with a large diameter.

There were some locomotives that looked a bit like Garratts at first sight, with a long rigid frame and power units at each end, described as "Modified Fairlies". The coal and water were in the same place as Garratts but above the long frame instead of the power units

They were built by North British in Glasgow, designed to look like Garratts and sold to South Africa. The long rigid frame was their undoing, due to huge overhang on curves.

There are some pictures at