How about an articulated or a mallet?

I would definitely have Trevithick's 1803-4 locomotive top my list. Stephenson is often unfairly portrayed as "the father of steam locomotion" when it was the former who laid the groundwork.

In the US, the American Standard 4-4-0, which allowed the light and rough railways to be used to more rapidly open new country to development in all classes of service.

In the UK the inside connected 0-6-0T, which handled the majority of trains for decades.

In industry everywhere the ubiquitous 0-4-0T.

In US freight service on mature railways, the 2-8-0. More of these were built than any other wheel arrangement.

ALL of these were of course developments of the essential Stephensonian improvements to Trevethick's early work in making Watt's noncondensing cylinder steam engine mobile.

dave

I will have to think a bit about this. Three things that quickly come to mind are:

Cole's experimental Pacific at Alco, that became the K29 design for PRR;

The idea and principles behind the USRA locomotive standardization

The AMC Berkshire designs (and their logical scaling-up to ten-coupled)


These are examples of groundbreaking design with far-reaching consequences. An example of something that was important in a number of respects was the Four Aces 4-8-4, which aside from its use as a demonstrator of important technology is interesting for being a 'rightsized' locomotive for a wide range of services.

I agree with Dave about the 4-4-0 ... but a particular sort of 4-4-0: the 'melody cast and wrought in metal' standard American 4-4-0, with the separable frame, wheels flanking the sylinders, proper proportions, etc. (It is interesting to see how quickly the 'logical' progression with a large firebox went past the 4-4-2 to the 4-6-2 in America).

While the 0-6-0 was ubiquitous in Britain, it was scarcely an example of groundbreaking design sublimity... I'd propose the Churchward/Collett 4-6-0 as a better exemplar (including its influence on Gresley's designs).

I'd also propose the Mikado, as the wide-firebox evolution of the 2-8-0, as a much better example even at comparatively small size.


What might be as interesting -- the three greatest flops in stam-locomotive design. Among these might be the use of compounding without superheat, the use of nickel steel in staybolted locomotive boilers, and the general idea of three-cylinder locomotives in American practice. (Note that I pointedly leave out duplex-drive locomotives, although arguments could certainly be made :-})

I'm not a student of British steam, so someone educate me about the virtues of inside connected locomotives. I would have thought them to be a nightmare to maintain.

They are, Frisco. It is important by virtue of its use with little variation on many lines for many decades as a "standard" locomotive. Like many things British (Lucas electrics, warm beer, running plumbing on the outside walls of buildings to let it freeze quicker) they are quirky and inconvenient, but popular nonetheless. The question was of importance, not highest technology. Hard to beat the Lima Superpower Berks or the N&W steamers for technological importance in the US, and works of Chapelon and Porta in other parts of the world.

This is a corollary to the idea of choosing a 2-8-0. To me, one of the most fascinating aspects of steam locomotive development between the wars was the work done by the D&H to develop a powerful and efficient drag freight locomotive. It is described in J Parker Lamb's book, "Perfecting the American Steam Locomotive" on pages 73-76. That book is on Google Books, and here is the link (I hope it works):

https://books.google.ca/books?id=AzJCeF ... es&f=false

Too bad this work was not applied to a greater extent.

I agree completely with the mention of the use of superheated steam. It allowed great advances in locomotive performance and increases in efficiency.

I will not deny that there were A LOT of 2-8-0s built, but, from what I have been able to gather, this statement isn't completely true. If you're saying that the 2-8-0 was the most produced wheel arrangement in the world (including 2-8-0s from every country), then you might be right. I don't know those numbers. However, if you're referring to just the United States, then the 2-8-0 was not the most produced wheel arrangement. From the information I have gathered, the most produced wheel arrangement (for a steam locomotive) in the United States was the 4-4-0 American (with 25,000-26,000 locomotives of that wheel arrangement being produced from 1836-1928).

Hi,

Concerning the next step from the 4-4-0 and the 2-8-0, there are a couple of thoughts.

1) the 2-8-0 made the conquering of the heavy mountians (such as Colorado, Alaska - Yokon Territories, etc) economically possible. Two 4-4-0s MIGHT not equal a 2-8-0. Given PRR's unique development path would be an exception to the rule.

2) The 4-4-0 design on the Rio Grande had troubles with the line parallel to the Front Range (Denver to Trinadad). They started from 2-4-0 (passenger) and 4-4-0 (freight) moved quickly to 2-6-0s and 2-8-0s. Not conclusive but suggestive.

3) if you are considering locomotive technology, the shay (and other geared locos) were great advances. Same can be said for the articulateds and mallets in a later time frame.

4) locomotive technology - superheating I think would be next.

5) I think the PRRs duplexes were a good next step (lower weight of recipricating parts), PRR had 50 T1 4-4-4-4s and canceled an order for 24 as yet unbuilt M1 4-8-2a for the promising Q2 4-4-6-4 duplexes. The dulexes never had the time to get the bugs worked out. Their lack of acceptance, I believe, was that they could not compete with diesels and not that they could not compete with other steamers. Because of this, the PRR duplexes are a sort of a footnote and not a loco for consideration.

6) The Garrett was a good advancement for an alternative to the articulateds. They were used in the 100's. Not a great advancement. The fuel and water argument concerning the garratts is a non-starter. If the bulk of the pulling power was due to the fuel on board, then any tank loco (0-4-0t, 0-6-0t, 4-6-2t, etc) would have been also a failure.

7) I am not sure how to rank compounds.

FWIW

Doug vV

Geoff said


One of the very greatest flops in all of steam history was the misguided seeking after technically high thermodynamic efficiency -- and perhaps nowhere did this get the penny-wise and pound-foolish treatment more amazingly than with those four locomotives.

An illustrative comparison can be made between the high-pressure experimentals and the D&H's later 4-6-6-4s. The object of the exercise is to run trains, and not tie up the main or be unavailable with breakdowns, rather than squeeze the most out of a Red Edge scoop worth of the cheapest possible coal. A very good distinction might be drawn (as I did, implicitly) between the original Super-Power engines, which were relatively speaking dogs, and the AMC version of the Berkshire (and, in a different sense, the T&P rebuilding of their early 2-10-4s into practical higher-speed locomotives...)

Most other places you saw the emphasis, you got problems -- take the Franco-Crosti economizer. (Please!) Or any road locomotive with a steam pressure in excess of about 300 psi ... or practical use of poppet valves in American service, or many applications of feedwater heater.

The big difference is the evolution of the Schmidt 'smoketube' superheater ... which is much more a performance-enhancing device than a "fuel-saving" one, when you look at what it does.

If you want better examples of reasonable thermodynamic optimization, look to Chapelon's 242 A1 and 160 A1 for your inspiration...

1) Rocket (firetube boiler, direct drive)

2) 4-4-0 (three point suspension)

3) trailing truck and wide firebox

4) Superheat (superheater element in firetube)

5) Rotary poppet valve gear

If I am not mistaken, the C&O 2-10-4 came first, and the AMC Berkshire was a cut-down version of it.

The origin of the inside connected locomotive was Robert Stephenson's third design for the Liverpool & Manchester Railway, the Planet of 1830. The reason was to increase thermal efficiency by heating the cylinders in an extension of the smokebox. This reduced the coke consumption per mile from 27-28 lbs. to 19 lbs.
The burning of coke was the result of the requirement of the railway for the engines that competed in the Rainhill Trials to consume their own smoke. Pollution control in 1829.
Robert Stephenson borrowed several ideas or inventions for his engines, but he was the first to combine them into a much improved locomotive.

Tom Hamilton

1 Discovery that a gas under pressure could do work
2. Concept of valve gear for constant motion
3. Three point suspension
4. Improvements in METALLURGY leading to the Bessemer process that allowed various designs to be tried. This is not only for locomotive design but for all railroad construction needs (cars bridges rail etc.)
5. Development of industry standards that created the ability of interchange which helped improve transportation size and lowered cost to encourage growth and the need for more modern or improved locomotives.

Mr. Fred Springer(former VP of Mobil oil) brought Mr. Bistline (sp?) of Southern/NS to speak at the SWC of the R&LHS. Mr. Bistline said everyone wanted to talk to him about the steam program but his biggest impact on railroading was the Big John Car case. In looking at history we sometimes want to look at the things that interest us and not the bigger picture that allowed things to happen.

Robby