Liveries!

The GWR taper boiler 4-4-0s had over 20sq ft as did the NER R class. The SECR E class was 21sq ft

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Yes, I found the R class just after I posted!
Just goes to show you need to be thorough in these matters... Mea culpa!
Nevertheless, the Webb 2-2-2-0 long preceded these classes, and had a large grate for its time. Webb thought this could only achieved without coupling the wheels. He was wrong, but it was quite a conventional opinion at the time.

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The Drummond 4-4-0s / 4-2-2-0s present a very clear series of how firebox size, grate area and heating surface are constrained by wheel spacing:

C8 (1898)
Wheelbase: 9'0"
Driving wheel diameter: 6'7"
Firebox length: 6'4"
Grate area: 20.4 sq ft
Firebox heating surface: 124 sq ft

T9 (1899)
Wheelbase: 10'0"
Driving wheel diameter: 6'7"
Firebox length: 7'4"
Grate area: 24 sq ft
Firebox heating surface: 143 sq ft

E10 (1901)
Wheelbase: 11'0"
Driving wheel diameter: 6'7"
Firebox length: 8'4"
Grate area: 27.4 sq ft
Firebox heating surface: 156 sq ft

All three had the same wheel diameter and essentially similar boilers: every foot of extra length between driving wheels added a foot of firebox length, 3.5 sq ft of grate area and around 15sq foot of heating surface; but by time you got to to the E10, the driving wheels were uncoupled. The C8s were already under-boilered even when new.

Tom

 

I think it was Patrick Stirling who said, an express loco with coupled wheels was like a man trying Run with his breaches down.

 

It was indeed, and what a brilliant description! And that was in the days of inside valvegear! What would he have made of a Schools?!

Richard.

 

In the Victorian era, Stroudley and Drummond were also notable proponents of large fireboxes and grates. Drummond's NBR "Abbotsford" class 4-4-0 had a grate area of 21 sq ft, very large and heavy engines for 1876. That came down to 19.5 sq ft in Drummond's Caledonian 66-class, even though that class was in most respects an "Abbotsford" clone - not sure whether that was due to altered firebox water spaces or simply the wish to standardize the boiler with the "Jumbo" (294-class) 0-6-0.

 

Even with perfect geometry you can get some surprising results if you model it numerically rather than purely analytically. When I was a young undergrad I was introduced to 3D CAD and motion modelling software. Being the fan of modern technology that I am, I promptly set to modelling up a six coupled, three cylinder, unified drive locomotive chassis. Anyone wondering whether it might have resembled a Bulleid may be on the right lines. Being lazy, I thought it would be a much easier way of calculating the out-of-balance forces than trigonometry and Taylor series, since you could put force reaction probes in the "axlebox" bearings. However, it turned out that even with numerically perfect geometry and fixed positions of every axle, the force reaction probes spiked to infinity every time a coupling rod passed through the dead centres, which rather negated having it six-coupled. It was something of a surprise to me, since I'd just assumed the rods on the other side would do the work as one side passed dead centre, but with infinitely stiff components and zero clearance that isn't quite the case. Real engines bend and have clearances, of course, so infinite forces don't happen in the same way.

On another note, I would bet that the length of coupling rods used in this country up until the end of the 4-4-0's supremacy probably tracked (crudely) the strength and consistency of the available steel. For a given rod cross section and rotational speed, the bending stresses at speed go up with the square of the length, so Drummond going from 9' on the C8 to 10' on the T9 was close on a 25% increase in loading, like for like. You can deepen the section of course and get geometry on your side, but then the mass goes up too and returns are diminished.

 

Still, getting back to the topic of the thread, marvellous liveries on all these 4-4-0s, 2-2-2-0s and 4-2-2-0s....

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Interesting discussion, to add a note to Tom's contribution Drummond's D15s also had a 10' coupled wheelbase and when I was researching for a model it would seem that 10' appears to be a practical limit on most British railway 4-4-0s of the Edwardian era, apart from the mentioned Eastleigh oddities.

Bluetrain raised an interesting point about Caley boilers, I have just started Vol 2 of the CR locos book and indeed there was a standard boiler that was used on many classes, certainly the 66 and 294 classes, and long into the LMS era apparently. BTW the book is excellent, highly recommended.
Regards
Martin

 

In terms of basic dimensions, steam locomotives in the UK are largely designed by parameters outside the control of the draughtsman. The frame plates are controlled by the rail gauge and control the width of the firebox, unless you go wide firebox, and the length is constrained by wheel spacing, which is constrained by both track curvature and boiler length. firebox depth is controlled by wheel diameter, not to mention ashpan size. Boiler size is limited by loading gauge, the wheel diameter and the ability of the driver to see forward. Boiler length is a compromise to some extent determined by cylinder position, notwithstanding the need to maintain a satisfactory tube length/diameter ratio. Then there is the civil engineer to satisfy, oh and let's not forget those operating people. The draughtsmans skill is in designing a loco to fit all these compromising parameters and make it work.

 

Don't think that anyone could disagree with that sentiment. Although if judging purely on livery, my votes would go to the Caledonian Dunalastairs and Great Eastern Claud Hamiltons! And naturally not forgetting the S&DJR.

The D15s introduced significant changes to previous Drummond practice. One change was the use of a grate that sloped and extended over the rear axle, so that 27 sq ft grate could be accommodated without extending the 10 ft coupled wheelbase inherited from the smaller T9 and L12 classes. This design option was increasingly adopted as larger 4-4-0 designs were introduced after 1900 - Claud Hamilton, City of Truro, Midland Compound, GC Director, etc.

 

I'm not going to suggest a new build. No not at all.

But if I did it would be the prototype 3 cyl 0-8-0 which would be interesting to test. It would surely be capable of some useful work at speeds up to 25mph?

Incidentally I understood that at least part of the reason for uncoupled wheels was the very restrictive LNWR loading gauge below platform level. That was still a problem in the 1920's, part of the reason why the Crabs had their cylinders shoved halfway up their sides. Stanier confronted the issue and got the Civils to back down.

Good stuff on the Webb/Whale/Bowen-Cooke saga in this book:

https://www.amazon.co.uk/Crewe-Locomotive-Works-Its-Men/dp/B00SLRBOF4

Sorry, I digress. It's late and I'm slowly going stir crazy - on a 14 day lockdown because of exposure to a Covid-infected person.

 

Sorry about your quarantine.
I thought Stanier got round the issue with higher boiler pressure and hence smaller cylinders?
@LMS2968 will be able to confirm

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Very true, Mate, he did, but that still wasn't sufficient for the Chief Civil Engineer, who produced a list of locations where the new 2-6-0's cylinders would foul the loading gauge. Stanier's answer was to fit lead 'fingers' to the latter engine's profile and run it through all the places listed. In only a few were the fingers bent, so proving that, mostly, clearance existed, and gave the CCE the job of moving back platform copings in those places where it didn't.

 

My favourite as well.The two outside cylinders were 15 inch sitting 6 feet 8 apart.
The Teutonics had 14 inch outside cylinders sitting 6 feet 6 apart

Thank You ,I have ordered one for 10£ postage to Denmark included.
Steam-crazy old men are getting a diminishing group.

 

Interesting. According to the gauge I've seen the LNWR gauge was not especially restrictive below platform level: 8'8.5in, half an inch wider than many other lines, including the L&Y. The Midland was a tad wider at 8'9". The GW was about the widest at platform height, but only because they accepted a much smaller platform to gauge clearance than anyone else.

One may note that Stanier's lead fingers were a more subtle way of doing what Churchward had done at the turn of the century when he fitted a Dean single with dummy outside cylinders and sent it all round the system to see what hit.

I've not found a copy of an LMS composite gauge, but there surely must have been one. If anyone has a copy I would love to see it.

 

The Claughtons were 8ft 8in over platforms, but earlier LNWR engines were generally narrower. A Webb Teutonic appears (from a faded diagram) to be 8ft 3in overall width. I wonder whether, back in the 1880s, any of the early Liverpool & Manchester lines still had their original narrow track spacing, which could have affected Webb's design options.

Ref the "LMS composite loading gauge" I suspect that there was more than one of them. For Black Jobs (Stanier Class 5 and below), the LMS seems to have built within both the LNWR width below platform and the Caledonian height limit (12ft 11in), so that the general purpose engines were "loading gauge friendly" just about everywhere. But LMS-built Big Red Engines were up to 13ft 2½in high and were able to operate to Glasgow, in spite of being too high according to Caledonian and GSWR loading gauges.

 

the first batch of Claughtons had a piece "nibbled" out of the buffer beam after striking platform ends, which suggests they were at the maximum possible width

 

It got complicated for sure. The GWR General Appendix to the rule book has four pages of restrictions as to what coaching stock may be used on which GWR lines. There's a story in Cook's Swindon steam where he was driving a 4700 during the General Strike, and was diverted through Weston Super Mare, and, unsure as to whether the 47 was actually allowed down that route, coasted the train very gingerly through the station.

 

This thread seems to have drifted quite a lot - surely a split is in order?