What Ifs, and Locos that never were.

Looking at the Urie 4-8-0 drawing in Townroe, there is basic flaw - there is no room to mount the brake hangers between the couple wheels! 5'-3" wheels at 5'-6" centres! IMHO a finer looking beast than the Maunsell version (I wonder which naval heroes would have been commemorated on those?)
Pat

 

A Franco-Crosti-Caprotti class 5? Something very similar did exist. Not the prettiest loco ever...

 

You want Handsome ?

 

I'll have to look up Townroe's book. However, it strikes me that if the proposal is to go to 5'3" wheels, you really don't gain a whole lot that an S15 (with 5'6" wheels) doesn't already give you.

You could then go smaller. However, the SR (and its antecedents) made few, if any, mainline freight locos with wheels smaller than about 5'0", for the very good reason that even the freight engines had to deputise on passenger workings from time to time. There is no SECR / LBSCR / LSWR equivalent of an NER P2 0-6-0 or LNWR 0-8-0 coal engines; no SR equivalent of a GWR 2884 or 8F. The LSWR did build a 4-8-0T of course with 4'8.5" wheels, the G16 hump shunters. However (and ignoring the known issues of those locos in their designed role), I'd like to see it sketched out how the relative disposition of axles, firebox and cab etc was to be managed in a tender engine variant.

Of course, the purpose of exploratory designs at a drawing office is to work through those considerations, so as to progress promising lines and reject unpromising ones - but it feels like a Urie 4-8-0 doesn't lead to a lot of promise, in my eyes.

Tom

 

Could, but not without that bringing it's share of issues, as the GWR discovered, when it inherited Galloping Alice, an 1895 BP 2-6-0 with 4ft drivers from the MSWJR (despite rumours which I fell for, not originally built for a line in S. America). There was a very good reason why it earned it's unofficial moniker! Any distressing ride issues evidently didn't surface pre-grouping, as the MSWJR deliberately set out to buy second example in 1897.

The CIÉ's comprehensive review of (southern) Irish locos, in 1948, made pointed comments about the negative impact of smaller driving wheels on maintenance costs. Mr.Bulleid was a member of the team responsible for said report.

 

There are ways and means! The first two pairs of 6'8.5in driving wheels on a GWR Star, Saint or Castle are at 7'0 centres.

 

New Zealand had a class (the JA) of two cylinder 4-8-2 with 4'6" driving wheels that seemed to ride OK, and went to reasonable speeds by NZ standards. So I don't think there is an absolute problem with smaller wheels, but it wasn't the done thing by the SR, where all the goods engines had wheels of 5' diameter or larger.

From a scan of Townroe's book, he says "proposed Urie 4-8-0" with a diagram, but doesn't seem to mention it in the text! (But I only skimmed quickly).

Tom

 

The Kiwis use Cape Gauge, of course, so ideas of what constitutes high speeds, certainly away from the trunk routes, is very different. Even later NZGR 'prime movers' (Classes K, J, Ja, Jb) only utilised 4'-6" dia drivers.

TBH, once I'd mentioned OVSB and Ireland in one post, I'm a tad surprised you didn't jump on 'The Turf Burner's' 3'-7" driving wheel diameter!

 

Iain's build thread is here:
https://www.rmweb.co.uk/community/index.php?/topic/99006-br-caprotti-crosti-standard-5/

He says "I've come across 2 drawings of this: one in the Edward Talbot book on Standard Steam (vol 1) and one in the RCTS Standard Steam vol 2. Some of the raw materials for the project are pictured with the drawing from the RCTS book."

Incidentally I also did that 2-8-2 photoshop above - an early one and very much a bodge as it has 9F wheels still!

 

I do apologise, I thought it was Mr. Tiley's work.... I used to look at the page on RMWeb and think they were superb images, and the alternative design history information was really good too... I loved the Gresley Atlantics, and the proposed Gresley Pacific based on the Ivatt Atlantics...
Is your alternative deign histories page still in existence?

Superb photo manipulation!

Richard.

 

Aha! I found the link to the images! I knew I'd bookmarked it ages ago, but couldn't locate it... Some absolutely superb machines here, something for everyone!

https://www.rmweb.co.uk/community/index.php?/gallery/album/1412-alternative-design-history/

Richard.

 

Oooopsss!
I've just looked it up again - 5'-1" wheels. Still precious little room between the flanges.
As to the advantage (or otherwise) of the wheel size over the 498 Class, it's probably to do with limiting the coupled wheelbase. 1'-6" saved, I reckon.
Pat

 

The L&Y Aspinall Atlantics had 7ft 3in drivers at 7ft 6in centres. But the record for close wheel spacing was probably on the GN and LBSC Atlantics, built with 6ft 7½in drivers at 6ft 10in centres, leaving a quarter inch gap between the wheel flanges (1.125in deep). When the GN Atlantics were subsequently given thicker tyres to bring the driver diameter up to 6ft 8in, the flanges had to be reduced from the normal depth.

 

Sounds workable to me. To pick a not-entirely-random example, the EAR Class 28 2-8-2 had 4'3" coupled wheels at 4'6" centres. The trick is to use split hangers coming either side of the wheels, there's a good picture of one of the later, smaller Class 31s with its motion down here, showing how it's done. Not perhaps in the Urie tradition of simplicity, but also not exactly breaking the bank.

 

That is a really interesting table, although I'll quietly suggest that the clue to what made the difference for the round-topped engines is in the only class that appears three times (while not having a round top firebox). The LNER seems to have been a high superheat line from Gresley's day onwards. But also, look at the evaporation of water per lb of coal on the Merchant Navy. 280 psi boiler (at that time), decent steam temperature and it's still second only to the Duchess, which was producing steam at lower temperature and pressure. Although it depends a little bit on your assumptions, I'll suggest there's really nothing in it between those two boilers for efficiency, with a little bit of daylight to the rest.

This also emphasises what a poor job the valve gear and cylinders were doing on the original Bulleid Pacifics; both boilers high up in the evaporative efficiency stakes and two of the worst performances in terms of lb of coal per dbhp hour.

The other point about their valve gear concerns starting. Look at the valve travel compared to all the other classes with 1.625" lap; give or take a bit for lead, the longer the travel for a given lap the longer the maximum cut-off, but they have the shortest valve travel of all at 6.25", shorter even than the notably short lap Royal Scots (which I think had a lot of lead). There's no way they had 75% full gear cut off if those figures are correct, they must been closer to 65% in full gear like the Gresley engines before the war. No wonder they had a reputation for being tricky to start; compare also to the Kings with the same 1.625" lap but 7.25" travel - another reason for their famed low-speed sure-footedness (in addition to their rather misleading weight diagram).

The Scots are also quite interesting - their evaporative efficiency is nothing exceptional (although I don't believe that figure is corrected for superheat temperature), their valve gear statistics unpromising, but a high overall efficiency.

 

Fine looking, well proportioned locos they were too. Metre gauge, of course and I recall a comment of Dusty Durrant's: Speed is not a noted African characteristic! On a mainline with a gradient profile which makes Shap and Beattock look like billiard tables, not really too surprising

To my mind, of all the ex-British colony lines in Sub-Saharan Africa, the EAR, with it's well maintained fleet and attractive livery, had some of the finest looking locos anywhere on the continent (even the Garratts) .... though the Nigerian Class 4005 pacifics (Nasmyth Wilson of 1925, 5ft drivers, btw. Restricted to 70kph, which seemed more to do with pw, apparently) ran them a very close second ....

 

I think one of the KAs got up to close to 80mph if I remember rightly - the NZR speed record.

I had a footplate ride on a JA some years ago, at, ahem, heritage line speeds. Seemed to ride OK to me!

(Big chuffer alert: I reckon the train weight was about 125 tons, five wooden bogie carriages, for which the rostered motive power was not one but two JA class locos. Didn't half accelerate! Air-braked too, for our air-braked wooden carriages correspondent ...)

Tom

 

A large number of 2-8-0s had been built during WW2, so no need for any more. The purchase of the WD 2-8-0s allowed withdrawal of many existing engines, including the ex-NER Q5s and most of the fairly modern but unsatisfactory Fowler 7F 0-8-0s.

When Churchward introduced the 28XX in 1903, he effectively created the largest freight loco that could usefully be employed in Britain for most of the remaining steam age. So long as we were stuck with most freight movement being in trains of low capacity wagons without continuous brakes, those trains could only move slowly, while the total train length and weight was constrained by limited brake power and coupling strength as well as by loop and siding lengths.

So there was effectively a pause in British freight locomotive development between 1903 and the 1954 introduction of the 9F, barring false starts with the Gresley P1s and LMS Garratts. During that era, the 2-10-0 became established as the standard heavy freight type in many European countries. But until Riddles arrived on the scene, very few 2-10-0s had been built in Britain. The most significant appear to have been a class of 30 4-cylinder 2-10-0s built in 1920 by NB for a hilly route in India.

https://www.flickr.com/photos/124446949@N06/35681518620/in/photostream/

But these engines were exceptional. In overseas railways under British influence, the usual step-up from the 2-8-0 was to a small-wheeled 2-8-2, analogous to the Gresley P1 and to the 2-8-2s projected (but not built) by Hughes and Fowler for the LMS. Lots of 2-8-2s in India, Australia, etc.

 

I just looked up those Indian 2-10-0 locos. Over 50,000 lbf tractive effort! But in GIPR use limited to 60 wagons due to loop length, and 1600 tons due to coupling strength.

 

The EAR had the same issues with the mighty impressive Class 59 'double mountain' Garratts. Two survive in preservation in Nairobi, of which 5918 Mount Gelai has certainly operated in recent years.

Here, there's at least one fine 71/4" gauge model. Inspiration or lunacy? Whatever, it looks absolutely magnificent. Oh, for a garden big enough!