Imaginary Locomotives

[PhilJ W]

8 hours ago, DK123GWR said:

Though silly, the idea of using a 1-Co bogie seems strangely appealing.

I don't see why not.

[rockershovel]

16 hours ago, PhilJ W said:

I came across this item about a possible replacement for the 08 diesel shunter.

https://www.railwaygazette.com/uk/class-08-locomotive-replacement-concept-unveiled/61795.article?ID=z9xqh~9ntftt~nzqxhz~W4ik~Ky0gk&utm_campaign=RG-RBUK-RG Smartrail - 090622-JM&utm_medium=email&utm_source=newsletter&utm_content=RG-RBUK-RG Smartrail - 090622-JM&adredir=1&adredir=1

It uses a single bogie from a redundant/scrapped SD-40 (class 59). I wonder if a similar locomotive could be built using a British bogie?

Tri-ang were right all along! 

 

Edited June 10, 2022 by rockershovel

[rockershovel]

13 hours ago, AlfaZagato said:

No reason why it couldn't be done.   Only reason to do so would be if there was a UK made bogie still well supplied. 

Why, have the railways run out of ex-MR 0-6-0 chassis then?

[lanchester]

Thing I've wondered about for a long time - why was a 2-4-4 wheel arrangement almost unknown (tank or tender) in the UK. (I understand the arrangement was called the 'Boston' and there were a few in the US; also in parts of Europe, but never many, and none that I can find in Britain. I'm not counting 2-4-4 Mallet, or Forney 'logging' types, although I think Bachmann did one of the latter).

 

On the face of it, you might think think a leading pony truck to give some 'steer' but, especially if you are taper boilered and perhaps unsuperheated, not carrying too much weight. Two driving axles carrying most of the fixed adhesive weight; and a rear bogie carrying, and clearing, any weight of firebox plus, if you are in tank mode, a generous coal/water bunker (and if you get the springing right, perhaps a better ride for the crew).

 

But I am not aware of any locomotives, at least working in Britain, (we might have built some for abroad?) of that arrangement.  2-4-2T were common on many lines - you could have added a rear bogie just for range (and probably still fit the available turntables). Whereas 2-6-2T or 2-6-4T tend to be quite significantly bigger locomotives, and 'Atlantic' tanks seem to me to be putting the extra carrying capacity at the wrong end..

 

Now, full disclosure, I failed my Mech Eng degree twice, (although that was final year at a Russell Group University so that is almost a qualification in the modern world).so I may well be missing something obvious. But I am curious why no-one here went down that road (and heaven knows, some of our finest locomotive engineers explored most other by-ways).

 

And now the fun bit - what would a 2-4-4 or 2-4-4T by say Worsdell or Stroudley or Johnson or Dean (I'm not suggesting eg Churchward cos I imagine the extra weight of superheat into the 1900's might change the equation). I can't do the pix /graphics ec but anyone out there like to have a go? oR explain why this is a no-go?

[Compound2632]

1 hour ago, lanchester said:

Thing I've wondered about for a long time - why was a 2-4-4 wheel arrangement almost unknown (tank or tender) in the UK.

 

Think of a tank engine as a tender engine with a bunker stuck on the back. 

 

On virtually all inside-cylinder locomotives, the axle immediately in front of the firebox is the driven axle. One then has an axle ahead of that, just in rear of or below the cylinders, and an axle to the rear of the firebox. Both can be carrying axles (2-2-2), or the leading axle can be coupled to the driving axle (0-4-2) or the trailing axle (2-4-0) or both (0-6-0). 

 

Now put a small bunker on the back and you've got a small tank engine with relatively limited range: 2-2-2T (popular in Ireland), 0-4-2T, 2-4-0T, and the common-or-garden 0-6-0T.

 

In some specific circumstances, such as the twisty lines of the Metropolitan Railway, a rigid 6-wheeler isn't such a good idea so you replace the leading axle of a 2-4-0T with a bogie - and you've got a 4-4-0T.

 

Next, you want a bigger tank engine with a greater coal capacity - for suburban passenger work or heavy trip freights. Bigger bunker - an additional axle under the bunker - roll up the late Victorian 0-4-4T (where the two trailing axles are mounted in a bogie frame), 2-4-2T, and 0-6-2T. 

 

Meanwhile, out on the main lines, the virtues of the leading bogie for fast running are becoming apparent - 4-4-0s and 4-2-2s. For fast passenger suburban work, you want to emulate that. So your 2-4-2T evolves into a 4-4-2T (thank you, Mr Robinson) - really, a 4-4-0 with a medium-sized bunker on the back - with the firebox sitting between the driven and coupled axle. (A bit more support at the front end helps with that superheater you've added, too.) But by this point, you're wanting greater coal and water capacity - that big boiler is squeezing the volume of the side tanks. So make that bunker bigger. That needs another carrying axle - so you've got a 4-4-4T, as tried on the Met and the NER, or your 0-6-2T grows into a 0-6-4T. 

 

Now for main line work, various people are experimenting with mixed results with adding an extra coupled axle between the cylinders and the driven axle, developing from 0-6-0 to 0-8-0 mineral engines and 4-4-0 to 4-6-0 passenger engines (with 4-4-2s by the way - related to the 4-2-2 in the same way as the 4-6-0 is to the 4-4-0). Can you do the same to make a big tank engine that way? of course, but it's a big engine so it'll need a big bunker - cue those behemoths the 0-8-4T heavy mineral tank engine and the 4-6-4T Baltic tank - never a great success.

 

Meanwhile, Mr Churchward has been experimenting with a leading truck ahead of the cylinders - it's what the Americans did, to keep their 0-6-0s and 0-8-0s from falling off their dodgy roads. In Britain it helps support a heavier front end with superheater and outside cylinders. Behold the 2-6-0 and 2-8-0. Do the same with your big tank engines: the 0-6-2T becomes a 2-6-2T and the 0-6-4T becomes the 2-6-4T, which experience goes to show is pretty much the ideal layout for a big passenger tank under British conditions.

 

In all this, the 0-4-2 -> 0-4-2T -> 0-4-4T evolutionary pathway has become a bit of a dead end, for all that the 0-4-4T was highly popular in the late 19th century and many examples of the type remained in use right up to early BR days. It's not really capable of being enlarged by the addition of an extra axle between cylinders and firebox, per the 4-4-0 -> 4-6-0 transition, though there were some examples of 0-6-4Ts arranged that way, in Ireland mostly. Give the 0-4-4T outside cylinders, and it'll waddle dreadfully. So there's really no route to needing that Churchwardian leading truck. The 2-4-4T just isn't a good place to go, when you look at the alternatives, with the British tradition.

 

On the continent, they did get to the outside-cylinder 2-4-4T; here's quite a zippy-looking one:

 

 

[Embedded link]

 

This really is a 0-4-4T that has been given outside cylinders and so needed a leading truck. I wonder how they got there, given that they didn't go through the inside-cylinder 0-4-4T stage, as far as I'm aware.

Edited June 10, 2022 by Compound2632

[tythatguy1312]

Interestingly I've never heard of a 4-2-2 tank, despite the fact that, on the surface, it doesn't sound like a horrendous idea for the early 1860's

[Compound2632]

8 minutes ago, tythatguy1312 said:

Interestingly I've never heard of a 4-2-2 tank, despite the fact that, on the surface, it doesn't sound like a horrendous idea for the early 1860's

 

NER No. 66 Aerolite was a 4-2-2T between 1892 and 1902 when it was rebuilt as a 2-2-4T:

 

 

It had started out as a 2-2-2T. The driven axle stayed in the usual place, ahead of the firebox, but in 1892 the leading axle was replaced by a bogie, as illustrated - undergoing the same mutation as a 2-4-0T would to make a 4-4-0T, keeping the short bunker. This was done, I think, to give more room for, and carry the weight of, the compound cylinders. On rebuilding as a simple, the leading bogie was dispensed with, returning to a single carrying axle, but a bigger bunker was wanted, with an additional axle to support it, so just as the 0-4-2T morphed to the 0-4-4T, the 2-2-2T morphed to a 2-2-4T. 

[2251]

1 hour ago, tythatguy1312 said:

Interestingly I've never heard of a 4-2-2 tank, despite the fact that, on the surface, it doesn't sound like a horrendous idea for the early 1860's

The Bristol & Exeter (inevitably) had quite a number. They were, I think, later re-built into tender locomotives.

[PhilJ W]

The 4-4-2T was quite rare as well but those that were built were quite successful. The LT&SR, apart from a few goods locomotives had nothing else, the only other ones were the Metropolitan F class. They were used for the same purpose, fast passenger trains over relatively short distances.

[Compound2632]

1 minute ago, PhilJ W said:

The 4-4-2T was quite rare as well but those that were built were quite successful. The LT&SR, apart from a few goods locomotives had nothing else, the only other ones were the Metropolitan F class. They were used for the same purpose, fast passenger trains over relatively short distances.

 

Like I said, thank you Mr Robinson:

 

 

An especially handsome example of the breed. And we should by no means overlook those of Messrs Ivatt, Reid, Adams in his Nine Elms days, and Marsh.

 

 

[rockershovel]

4-4-2s of all descriptions look rather stylish, I think... especially the Adams 4-4-2T

[rockershovel]

The American style 2-4-4T was basically a development of the Forney, given a leading truck to improve stability when running chimney-first. 

 

American tank locomotives very rarely had side tanks, I assume this is due to the prevalence of bar frames and lack of running plates, splashers etc. 

 

Hence the tendency to pannier, saddle or rear tanks and rear bogies with four, or even six wheels 

[PhilJ W]

11 minutes ago, rockershovel said:

4-4-2s of all descriptions look rather stylish, I think... especially the Adams 4-4-2T

It was only the increasing weight and/or length of trains that led to their replacement by six coupled locomotives.

[Northroader]

Churchward did ‘em, too.

[Compound2632]

3 minutes ago, Northroader said:

Churchward did ‘em, too.

 

Yes, how could I overlook those - and tank engine versions of 4-4-0s in name as well as fact.

[tythatguy1312]

18 minutes ago, rockershovel said:

or rear tanks

that honestly hits with some Irony considering almost no back tanks appear to have worked in the UK. That being said, at least one seems to be incredibly famous.

[Compound2632]

6 minutes ago, tythatguy1312 said:

almost no back tanks appear to have worked in the UK. 

 

Beg pardon?

 

 

it was more-or-less the standard configuration for 0-4-4Ts until S.W. Johnson invented the side-tank 0-4-4T in his Stratford days.

[tythatguy1312]

1 minute ago, Compound2632 said:

Beg pardon?

I'll admit I meant engines with the water tank on top of the frames but it's becoming increasingly obvious that my field of locomotive knowledge isn't exactly inclusive of the period from 1850-1900

[Compound2632]

15 minutes ago, tythatguy1312 said:

I'll admit I meant engines with the water tank on top of the frames but it's becoming increasingly obvious that my field of locomotive knowledge isn't exactly inclusive of the period from 1850-1900

 

In these engines, the 1,000 gal tank is on top of the frames - it's a back tank rather than a well tank. Martley's "Scotchmen" for the LC&DR were well tanks:

 

 

but the rear bogie of Kirtley's engines leaves no room for a well.

[rockershovel]

1 hour ago, Compound2632 said:

 

In these engines, the 1,000 gal tank is on top of the frames - it's a back tank rather than a well tank. Martley's "Scotchmen" for the LC&DR were well tanks:

 

 

but the rear bogie of Kirtley's engines leaves no room for a well.

That rates at least a mention in passing, in the "unsightly locos" thread....

[rockershovel]

Scratching my head over the "incredibly famous back tank"...

[JimC]

2 hours ago, tythatguy1312 said:

that honestly hits with some Irony considering almost no back tanks appear to have worked in the UK. That being said, at least one seems to be incredibly famous.

Back tank on its own, not many. Water tank under the coal space - common.

[DenysW]

Does it come down to what duty you'd use a 2-4-4T for in Great Britain? From Wikipedia:

 

"The Bavarian Class D XII steam locomotives were manufactured by the firm of Krauss from 1897 for the Royal Bavarian State Railways (Königlich Bayerische Staatsbahn). Ninety six of them were procured for service on the stub lines running from Munich into the mountains, but in reality they were stationed in many large Bavarian locomotive depots."

 

This doesn't ring true (to me) for GB if you substitute Manchester, Leeds or Newcastle for Munich, and the relevant pre-Grouping company for K.Bay.Sts.B. They were later reclassified as Pt 2/5, showing that they were thought of for passenger use (goods: G), but not express (S). One superheated variant was produced (Pt 2/5 H), but was not successful enough to generate more.

 

There's a nice HO-scale model by Trix, not in current production.

[Compound2632]

49 minutes ago, DenysW said:

"The Bavarian Class D XII steam locomotives were manufactured by the firm of Krauss from 1897 for the Royal Bavarian State Railways (Königlich Bayerische Staatsbahn). Ninety six of them were procured for service on the stub lines running from Munich into the mountains, but in reality they were stationed in many large Bavarian locomotive depots."

 

This doesn't ring true (to me) for GB if you substitute Manchester, Leeds or Newcastle for Munich, and the relevant pre-Grouping company for K.Bay.Sts.B.

 

Not so sure. Let's try, but with a 0-4-4T rather than a 2-4-4T:

 

"The Midland 1532 Class steam locomotives were manufactured at Derby Works from 1881 for the Midland Railway. Eighty five of them were procured for service on the stub lines running from Leeds and Bradford into the mountains of Ilkley and Otley, but in reality they were stationed in many large Midland locomotive depots."

Edited June 11, 2022 by Compound2632

[DenysW]

Even as an ex-Ilkley resident, I'd have to say hills, not mountains. But I think the difference between the Pennines and the Black or Franconian forests will have been the length of the slog, not the actual steepness of the inclines, these being set by the usual compromises between capital cost and the expected need for banking. The Midland line ran Ilkley to Skipton via Bolton Abbey to avoid the steep incline the modern road takes out of Addingham.

 

If true that it's the length of the slog, that then pushes you into the 2-4-4T to get the extra coal and water at the back (compared to, say, an L&Y 2-4-2T), and you aren't going to want the speed that gives 4 guiding wheels instead of two.