Imaginary Locomotives

[rockershovel]

1 minute ago, JimC said:

 

You remember better than me then. I'm not surprised!

 

 

https://www.rmweb.co.uk/community/index.php?/topic/14790-imaginary-locomotives/page/223/&tab=comments#comment-3669003

[The Johnster]

This one’s a bit different, not just an 8-coupled version of a15xx.  The boiler is a no.3, as opposed no.10, and the Churchward layout of outside cylinders and inside Stephenson valve gear is adhered to.  Like a lot of these sorts of proposals, it’s hard to see what use it might have been, hump shunting at the new Severn Tunnel yards perhaps?  It’s far too top heavy for all but the slowest work, and the existing locos were capable of the hump shunting; no wonder it wazza neverwazza!  It makes more sense as an 0-6-0, because then you can sit the firebox between the centre and trailing axles like pretty much every British 0-6-0 ever built and bring the boiler, and with it the centre of gravity, down to a decent level.  But then the wheels are too small...

[JimC]

On 30/01/2020 at 16:36, The Johnster said:

... not just an 8-coupled version of a 15xx.  

There's an idea...

Quite tricky to work up something vaguely believable for this. I spent a lot of time agonising over wheel positioning. I decided that if I called it a hump shunter and gave it 4ft1 wheels then the ashpan might just about work. 
Its got a Standard 2 boiler, and I'm imagining its one of the 225 psi variants, so the tractive effort is a tad over 28,000lbs, less than the big 2-8-0 tanks, but close to an SR Z class.  

This is now a Mk 3 - I realised I'd drawn the reversing shaft running through a driving wheel in the Mk 1... While the Mk 2 valve gear probably wouldn't have worked and there were problems with the brakes. More difficult than it looks this steam locomotive design...

 

 

 

 

 

Edited January 31, 2020 by JimC

[Ramblin Rich]

It looks more stable than a 15xx. I always thought they looked like they would nose dive with a good brake application!

[Ben Alder]

On 29/01/2020 at 07:56, Compound2632 said:

It's the lack of guard irons that gives that impression, I think.

 

Bit more work done on it and rudimentary irons added - coarse on screen but not noticed when on the layout beyond that they are there. One of the reasons I hadn't done this before is that the loco is from the second, DJ,  batch with his trademarks - split chassis  etc, but TBH, it runs far more smoothly than the O2 I have. However, the cylinders are not part of the chassis but screwed to the body, hanging loose when the two are separated so I wanted to make sure everything was OK before I tidied up the endings. Brass irons and a front plasticard frame  spacer are now in place to fill in the front, Evostuck in case I do have to take things apart ever, Pics of the HR Scrap tank don't really show any frame jutting under the cylinders so I left that be - my layout is on a low baseboard  due to the pitched roof of the attic it is in and a broadside view is not the norm  so this was not worth pursuing as a further detail...

 

 

[rodent279]

On 28/01/2020 at 18:26, Murican said:

Another thing I found compelling are several ideas for 4-8-0s on DeviantArt that I found. I'm from America, which is a country whose railroads rarely used 4-8-0s either, so they always seem to entrance me somehow.

 

The LNER Gresley T2:

https://www.deviantart.com/miscmischief48/art/Goodwill-LNER-T2-No-9954-Robert-767094659

 

The GWR Colliet Cathedrals:

https://www.deviantart.com/no1thomasfan2012/art/GWR-8000-Exeter-Cathedral-694498748

The Cathedral looks too much like an extended King, in fact with the narrow firebox & long barrel, I would have thought it would have been an indifferent steamer, like TGB. I know M. Chapelon managed to get some impressive performance out of his P-O (?) 4-8-0's, but he had the benefit of a larger loading gauge.

[rockershovel]

I think that on both sides of the Atlantic, the 4-6-0 represented the ultimate development of the 4-4-0 and grew about as big as locos of that type, usefully could. The next step was the 4-6-2 and 4-6-4, with the 4-6-2 being much the more successful of the two because of its superior adhesion, and the 4-6-4 developing into the 4-8-4 behemoths of the last days of steam. 

[rodent279]

I can't do the artwork, but my vision of a Swindon 4-8-0 would be something of a hybrid between this :- https://commons.m.wikimedia.org/wiki/File:240P.jpg#mw-jump-to-license

 

and a King. Possibly a smaller wheel diameter, say 6'3", would allow a larger boiler diameter, which might bring the ratio of diameter to length between tubeplates to something more like that of a King or Castle. Fully Chapelonised steam circuit, with angular or curved steam pipes from a position high up on the smoke box to the outside cylinders, Kylchap double chimney, and, dare I say it, compounding on the de Glehn system.

[Corbs]

10 hours ago, rodent279 said:

The Cathedral looks too much like an extended King, in fact with the narrow firebox & long barrel, I would have thought it would have been an indifferent steamer, like TGB. I know M. Chapelon managed to get some impressive performance out of his P-O (?) 4-8-0's, but he had the benefit of a larger loading gauge.

 

The 240A and 240P aren't massively bigger than the UK loading gauge from what I've seen in diagrams.

 

EDIT - this bit I wrote is obviously wrong when you look at a diagram: When people stretch the King into a 4-8-0 they often put the firebox between the last and second to last axles, like you would on the 4-6-0, which makes the boiler too long, but Chapelon's 4-8-0s had them further forward with the cab atop the rear drivers.

Note the back of the firebox is barely over the rear wheelset.

 

 

 

 

 

Edited February 1, 2020 by Corbs

[Dr Gerbil-Fritters]

2 hours ago, rodent279 said:

I can't do the artwork, but my vision of a Swindon 4-8-0 would be something of a hybrid between this :- https://commons.m.wikimedia.org/wiki/File:240P.jpg#mw-jump-to-license

 

and a King. Possibly a smaller wheel diameter, say 6'3", would allow a larger boiler diameter, which might bring the ratio of diameter to length between tubeplates to something more like that of a King or Castle. Fully Chapelonised steam circuit, with angular or curved steam pipes from a position high up on the smoke box to the outside cylinders, Kylchap double chimney, and, dare I say it, compounding on the de Glehn system.

 

Well, I had a go at that back on page 187....

 

 

It's probably time I did a better photoshop version...

[Corbs]

This one I did years ago, I think is too long in the boiler and demonstrates what I said above, the cab should be moved forward along with the firebox. Chapelon's 4-8-0s had split hopper ashpans (I believe) that went either side of the axle.

 

[rodent279]

2 hours ago, Corbs said:

 

The 240A and 240P aren't massively bigger than the UK loading gauge from what I've seen in diagrams.

 

When people stretch the King into a 4-8-0 they often put the firebox between the last and second to last axles, like you would on the 4-6-0, which makes the boiler too long, but Chapelon's 4-8-0s had them further forward with the cab atop the rear drivers.

Note the back of the firebox is barely over the rear wheelset.

 

 

 

 

 

I think that firebox & cab may be deceptive-look at the angle of the cab front plate. I suspect the boiler & firebox backplate is over, or close to, the rear axle.

Edited February 1, 2020 by rodent279

[JimC]

7 hours ago, rockershovel said:

I think that on both sides of the Atlantic, the 4-6-0 represented the ultimate development of the 4-4-0 and grew about as big as locos of that type, usefully could. The next step was the 4-6-2 and 4-6-4, with the 4-6-2 being much the more successful of the two because of its superior adhesion, and the 4-6-4 developing into the 4-8-4 behemoths of the last days of steam. 

I'm not sure you can characterise the successful 4-6-0s as 4-4-0 developments simply because the ones that obviously were 4-4-0 developments were mostly failures.  Churchward stated that ‘The modern Locomotive Question is principally a matter of boiler’, and its hard to disagree. Given a boiler that will be successful its then a question of putting a chassis under it. The narrow firebox seems superior to me because it has more surface area to fire volume for better heat transfer, the fly in the ointment being to get coal into it and ash out of it. I reckon the wide firebox works with a combustion chamber to get the heating surface to grate ratio to a more reasonable number, but It doesn't seem to me to be optimal, even if the practical problems of coal in and ash out are considerably easier. An oil fired GWR style 4-8-0 would almost certainly be a success, but brings you smack against the question "why would you want to burn oil in a steam locomotive when its so much more efficient to burn it in a diesel engine?"

 

 

[Flying Pig]

13 minutes ago, JimC said:

An oil fired GWR style 4-8-0 would almost certainly be a success, but brings you smack against the question "why would you want to burn oil in a steam locomotive when its so much more efficient to burn it in a diesel engine?"

 

Perhaps the oil-fired 4-8-0 can burn cheaper grades of oil than the diesel. Probably it can produce more power than a contemporary single unit diesel.  Certainly it will cost a lot less to acquire and can be operated using existing skills and facilities for the most part.  It looks like a good bet in 1947, not so much in 1967.

[Corbs]

45 minutes ago, rodent279 said:

I think that firebox & cab may be deceptive-look at the age of the cab front plate. I suspect the boiler & firebox backplate is over, or close to, the rear axle.

 

I'm such an idiot, given that I was literally just looking at this diagram before I posted that! You're right, it is.

Apologies for the error in the above post, I have edited it now.

 

[melmerby]

2 hours ago, Dr Gerbil-Fritters said:

 

Well, I had a go at that back on page 187....

 

 

 

It's probably time I did a better photoshop version...

Get rid of that nasty outside valve gear.

This is the GWR after all!

[JimC]

2 hours ago, Corbs said:

When people stretch the King into a 4-8-0 they often put the firebox between the last and second to last axles, like you would on the 4-6-0, which makes the boiler too long, but Chapelon's 4-8-0s had them further forward with the cab atop the rear drivers.

 

I think that's a good observation.  If it were humanly possible to hand fire a longer firebox than the King one then my inexpert guess is that  a longer box and the current King wheels moved forward would be the way to go, but it would require very clever ash pan design.  Here's (above) the layout of wheels and boiler (minus ashpan) on a King, and below the firebox extended about 20 inches and the wheels moved. Its obvious, I think, that all the problems will be around detail design of grate and ashpan. As I frequently failed to get across to executives, all strategies look fine on paper, its the detail where you fail... As a bonus if you could make this work it would probably have better RA than the King.

Edited February 1, 2020 by JimC

[rodent279]

2 hours ago, Corbs said:

 

I'm such an idiot, given that I was literally just looking at this diagram before I posted that! You're right, it is.

Apologies for the error in the above post, I have edited it now.

 

How do the boiler dimensions of a 240P compare to a King or a 47XX, in terms of barrel length, dia, no. and size of tubes, firebox heating surface etc?

Edited February 1, 2020 by rodent279

[rockershovel]

2 hours ago, JimC said:

I'm not sure you can characterise the successful 4-6-0s as 4-4-0 developments simply because the ones that obviously were 4-4-0 developments were mostly failures.  Churchward stated that ‘The modern Locomotive Question is principally a matter of boiler’, and its hard to disagree. Given a boiler that will be successful its then a question of putting a chassis under it. The narrow firebox seems superior to me because it has more surface area to fire volume for better heat transfer, the fly in the ointment being to get coal into it and ash out of it. I reckon the wide firebox works with a combustion chamber to get the heating surface to grate ratio to a more reasonable number, but It doesn't seem to me to be optimal, even if the practical problems of coal in and ash out are considerably easier. An oil fired GWR style 4-8-0 would almost certainly be a success, but brings you smack against the question "why would you want to burn oil in a steam locomotive when its so much more efficient to burn it in a diesel engine?"

 

 

 

... you seem to be making the point I was intending to make, which is that the narrow-firebox 4-6-0 is generally similar to the 4-4-0, whereas the 4-6-2, 4-6-4, 2-8-2 etc types with wide fireboxes over trailing trucks are a different type of loco, providing scope for mechanical stokers and greatly increased grate areas. 

 

The 4-6-0 was a very successful type on both sides of the Atlantic. 

[The Johnster]

On 31/01/2020 at 21:06, Ramblin Rich said:

It looks more stable than a 15xx. I always thought they looked like they would nose dive with a good brake application!

Amy Winehouse looked more stable than a 15xx...

 

Shoulda gone to rehab.

10 hours ago, rockershovel said:

I think that on both sides of the Atlantic, the 4-6-0 represented the ultimate development of the 4-4-0 and grew about as big as locos of that type, usefully could. The next step was the 4-6-2 and 4-6-4, with the 4-6-2 being much the more successful of the two because of its superior adhesion, and the 4-6-4 developing into the 4-8-4 behemoths of the last days of steam. 

I'd put it differently, agreeing that the 4-6-0 was the logical development of the 4-4-0, but would argue that the 4-6-2 and it's developees were the logical extensions of the 4-4-2, where the need to shoehorn the firebox between the axles is lessened by the trailing pony or radial.

[The Johnster]

2 hours ago, JimC said:

An oil fired GWR style 4-8-0 would almost certainly be a success, but brings you smack against the question "why would you want to burn oil in a steam locomotive when its so much more efficient to burn it in a diesel engine?"

 

Because until at the earliest 1955 (and there is a body of opinion that says 1960) it proved impossible to build a diesel electric or hydraulic loco of more than 1,600hp prime mover output within the restrictions of the British loading gauge and axle load requirements because you couldn't provide a generator or hydraulic pump that would cope with the output.  A 2k hp loco had been produced, the Fell, with. mechanical transmission.  2 major things happened in 1955, the BR modernisation plan and the production of DP1, which proved that it was possible to effectively double the output of the prime move and generate enough electrickery to transfer a useful amount of that output to the rail head.

 

I'd say there were good reasons for an oil fired 4-8-0 for very heavy passenger work up to 1955, but it    would have to have been a 3 or 4 cylinder loco to keep the cylinders small enough for the loading gauge, and the name of the game for BR steam was 2 cylinders.  The spec should IMHO have been an 800 ton train at 80mph with a tolerable ride quality.  But the realpolitik and economy of the time were not conducive to it.

[runs as required]

42 minutes ago, The Johnster said:

Because until at the earliest 1955 (and there is a body of opinion that says 1960) it proved impossible to build a diesel electric or hydraulic loco of more than 1,600hp prime mover output within the restrictions of the British loading gauge and axle load requirements because you couldn't provide a generator or hydraulic pump that would cope with the output.  A 2k hp loco had been produced, the Fell, with. mechanical transmission.  2 major things happened in 1955, the BR modernisation plan and the production of DP1, which proved that it was possible to effectively double the output of the prime move and generate enough electrickery to transfer a useful amount of that output to the rail head.

 

I'd say there were good reasons for an oil fired 4-8-0 for very heavy passenger work up to 1955, but it    would have to have been a 3 or 4 cylinder loco to keep the cylinders small enough for the loading gauge, and the name of the game for BR steam was 2 cylinders.  The spec should IMHO have been an 800 ton train at 80mph with a tolerable ride quality.  But the realpolitik and economy of the time were not conducive to it.

 

That is more or less true for these 4-8-2+2-8-4 beauts .

I watched them being towed along the East Lancs road to Liverpool docks in the mid 1950s as a student - and got to ride behind them up from Mombasa around the northern slopes of Kilimanjaro in the late 60s/early 70s.

They were 4 cylindered oil fired metre gauge and in effect 2 cylindered (for each articulated  'engine').

Orders for EAR&H after that IIRC were single cabbed English Electric diesels usually run in multiple like BR class 20s

dh

Edited February 1, 2020 by runs as required

[Corbs]

2 hours ago, rodent279 said:

How do the boiler dimensions compare to a King or a 47XX, in terms of barrel length, dia, no. and size of tubes, firebox hearing surface etc?

 

Not sure as I haven't found the relevant stats yet, La Locomotive a Vapeur is a very long book!

 

May I ask a potentially stupid question?

Better to speak out and risk being thought a fool whilst attempting to improve one's knowledge than to remain ignorant in timid silence.

 

Since large diameter cylinders are limited in UK loading gauge, was there any reason that two smaller cylinders could not be connected inline, with the same valve timing, a shared, long piston rod driving one connecting rod?

 

Like how on some hot rods you connect two engines driving a single crankshaft.

[Gibbo675]

31 minutes ago, Corbs said:

Since large diameter cylinders are limited in UK loading gauge, was there any reason that two smaller cylinders could not be connected inline, with the same valve timing, a shared, long piston rod driving one connecting rod?

Hi Corbs,

 

Two and three cylinders were quite often connected inline in the way you suggest in mill engines these were however rigidly mounted withing the engine bed which was  bolted to the masonry floor. I think that a locomotive would suffer from twist and vibration to a far too great an extent to allow it to work sufficiently well without trouble, maintenance would be a great problem.

 

Gibbo.

[rodent279]

Tandem engines, usually compounds, were quite common in mill and other stationary applications. There were some tandem locomotives, in the US I think, but it never became a big thing, probably because of what @Gibbo675 said above.

 

Edit:- I wonder if balancing may have been more difficult with tandems?

Edited February 2, 2020 by rodent279