Bulleid rebuilds - Was it for the better?

very interesting so far but i dont think any of you have got to the nub of the rebuilds. the report of the testing of MNs by BR at Rugby and on the road was extensive and covered the period November 1952 to January 1954. ive got a copy of the report. the report highlighted some very peculiar problems with the locos in their original form - even with the reverser clamped so it couldnt move. seriously erratic valvegear events, buckled coupling rods, insufficient 'top air', vibration at short cut offs, plus slipping all made for a dim view of the mechanics regardless of the excellent boiler which was never pressed to its upper limit on test for fear of damaging the loco and the test plant. a close analysis of the erratic valve gear results indicated that the chain driven valve gear had serious shortcomings and was preventing the full benefit of the locos from being obtained - hence Ron Jarvis' re-build.
cheers,
julian

 

Could be him, think its more a case of fast typing rather than spell checking. Ive heard of him before, but then when you prefer the likes of Worsdell, Raven, Collett and Stanier, hes not really needed.

 

i should add that the slipping wasnt just due to oil from the chain bath it was also due to the erratic behaviour of the valvegear which as steam pressure increased would suddenly develop much greater power (erratically) in excess of adhesion. the 1954 report is quite illuminating on this significant problem - which wasnt realised till the exhaustive testing in 1952-54. with a longer cut off and small regulator opening the problem didnt occur - but with short cut off and larger regulator opening sudden bursts of power would result, which had nothing to do with creeping of the reverser. in simple terms the valvegear had a 'mind of it's own' to do strange things outside the skill and control of the driver. this was regarded as a very serious problem. incidentally the report also tested a loco without syphons fitted, and showed it to be equal of the syphon fitted locos. hence my remarks a few months ago re 'ARCHIE's boiler repairs on the bluebell. sam ell couldnt improve on the original multiple jet blastpipe arrangement.

cheers,
julian

 

I have one of Prof Tuplin's fictionalised footplate stories called Spamcan Frolics, it covers many of the items mentioned so far on this thread, but additionally many firemen being keen to build up to full 280psi pressure before starting - this was guaranteed to produce slipping - much better to keep it below 240psi or even lower, the loco would still do all that was asked of it. Another point was the steam-operated firedoors, good in theory but if your foot slipped of the treadle you could do yourself an injury. I don't think it's any surprise the valvegear produced erratic results, being miniaturised any wear would be multiplied in the actual valve events.

Dave

 

Rather a narrow view of the world of steam but each to his own. You'll be telling me you don't like foreign locos next.

 

I'm curious as to what the relevance is of the screw reverser on an S15 to the power-operated reverser on a Bulleid pacific?

The Marsh I3 (which astounded the operating department on the LNWR with its capacity to work trains on minimal coal and water consumption, and was first successful superheated loco in the country); the Maunsell N (the first class to unite long travel valves, outside motion, maximum accessibility, Belpaire firebox, taper boiler and high superheat in one engine - effectively the loco that set the template for the BR standards, a generation and a half before "Britannia"); the Maunsell Schools (the equal of almost any 4-6-0 in the country, but packed into a 4-4-0 size loco) ... I could go on. Put simply, there were good locos on all regions (and pretty ropey ones, for that matter). But to claim that the Southern "always had poor engines" simply shows up your lack of knowledge on the subject.

Again, I'd urge you to actually find out a bit about railway working in the south before making such confident pronouncements. I'd have thought that a Merchant Navy pulling a 500 ton or so Devon Belle (which was generally 12 or 13 Pullman cars) up Honiton Bank (5 miles of 1:70/80) is at least the equal of a Duchess up Shap (4 miles of 1:75). And that is before you think about the 2 miles of 1:36 straight off the platform ends from Ilfracombe on the return journey. There are plenty of other steep gradients, many of which had the additional handicap of speed restrictions at their foot meaning they couldn't be rushed.

But the real complexity of working on the Southern, unmatched anywhere else, was the complexity of electrified suburban lines around London. The electrics ran sharply timed regular clock-face timetables; anything steam (whether a mainline express or the goods traffic) had to fit within that schedule, and woe-betide a train that caused a delay during the rush hour peak. Even freight trains in the London area had working timetables scheduled to the nearest thirty seconds; to run such services took both competent engines and enginemanship of the highest order. To have achieved it in a city notorious for its dense fogs was little short of miraculous. Add in the fact that the Southern had disproportionately large numbers of special workings (summer holiday traffic; race day traffic; school specials) when any available engine had to be pressed in to passenger service, and it explains the general propensity for mixed traffic engines, and why even the 0-6-0 goods tended to have a fair turn of speed, while there were no slogging 0-8-0s or 2-8-0s familiar from other railways.

Ultimately locomotive designers aren't mugs: they design locos to meet the traffic requirements, within the financial constraints that impinge on them. If you transplanted the Southern fleet to the Welsh valleys or the Durham coal fields, maybe there wouldn't have been an engine able to slog along at 20mph with 500 tons of minerals.. But I can sure as heck guarantee that if you sent the engines from the North East down to the south, equally the service would have quickly collapsed. It's horses for courses.

Tom

 

I'm afraid that your recent posts on this and other threads have only served to show your lack of steam locomotive knowledge. Why you should think a Q6 reverser is any better than a Bulleid, I don't know. They are both about equal. The difference is that you rarely want to finesse a Q6 reverser, which is perhaps fortunate, as you can't, whereas it would probably contribute to economic running with a Bulleid at 80+mph. As for the S15 reverser, it isn't steam operated for a start and there is nothing wrong with it and probably easier to use than a Black 5. Its inherent problem lies in the valve gear and way the radius rod is suspended which, incidentally, is the same as on a lot of LNER locos and most BR standards. And if you want to pit the steaming ability of an S15 with a Black 5 or B1, its no competition, the S15 will win hands down. In fact, a Black 5 is a poor steamer in comparison. The Southern certainly knew how to build boilers to do the job. And I'm a person brought up on a diet of locos beginning with 4 & 6.

Bulleid had some good ideas. His failing was in trying to develop them all at once in one type of locomotive.

 

Complete and utter drivel. You either have little knowledge of Southern designs or are simply trolling. The S15s were a superb mixed traffic design. Bullet proof and good steamers by all accounts. T9s were the equal of their contemporaries and the Schools were remarkable locos for a 4-4-0 - and this from someone brought up on GNR/LNER motive power.

 

As others have said most of the Southern designs were very capable, and were maids of all work engines, the S15's often got pressed into passinger work and kept to the timings, its a pity 30506 never went mainline, then you would have seen what they were capable of, but lifting 12 MK1's plus 70000, up medstead bank would give an indication.
I would rate the urie/ maunsel s15/n15/Arthur 's as probally one of the best designs of mixed traffic 2 cylinder 4-6-0's until the advent of the Standard 5. getting back to why the Bullied's were rebuilt, was to remove the problems that these engines gave the fitting staff, Chain driven valves, enclosed in an oil bath, having to undo a multitude of screws to remove sections of air smooth casing to effect boiler repairs, all at a time when the works staff would have been up against it, and the rebuilt engine, still had the superb boiler, but was certainly more fitter friendly , in fact had they not been rebuilt, they might have been withdrawn sooner, replaced with Britianias had it not been for the decision to electrify the network.

 

I stand to get shot down in flames here but was it not just the firebox that was welded with the barrel being riveted? There's an awful lot of big rivets in 34081's for an all welded job.

34081-19910400 by KING COBRA 92, on Flickr

 

You don't often see photos of Bulleid 4 - 0 - 2's on the move do you? Here's a recent photo of 257 Squadron's boiler, also with a lot of rivets.

https://picasaweb.google.com/116839141471298057728/Restoration2013#5934076802170500946

 

Solved the wheel slip problem but haulage capacity was markedly inferior to the 4-6-2 version.

 

Yes but has LESS moving parts; isn't that the epitome of efficiency ?

 

Isn't it the INNER firebox which is all welded?

 

In a word yes, Otherwise they wouldn't have bothered. You don't take locos out of service and incur cost for no good reason. The problem with the swivelled eye loonies (to steal a political phrase) who defend locos like a dog with its its food, is the exclusion of pragmatic operational and cost benefit considerations. Without those there is no railway.

Those who had to run the railway had perfectly sound reasons for rebuilding them.

 

Good point.

 

And these were the people who ordered some of the most useless diesels to have blighted the network. I'm sure their reasoning was "perfectly sound." Wouldn't trust their judgment based on that fiasco.

 

I had a look at Sir Archie in the works at Sheffield Park the other day. The cab and smokebox were removed, but the boiler was in situ, and it showed dramatically how strange the proportions are. Essentially, the firebox is very big - even bigger than the grate makes it appear, since the front slopes forward - and the smokebox is huge (something not readily apparent on an original with air-smoothed casing, and hard to see even on a rebuild behind the smoke deflectors). What is left in between is a little short stubby boiler barrel that barely reaches forward of the leading driving axle.

The effect I guess is twofold: firstly, a relatively large amount of the heating surface comes from the firebox, and a relatively small amount from the tubes (compare the table below, where in a WC/BB, 70% of the heating surface comes from the tubes and flues, in comparison with nearly 80% in a GWR King or Castle). Secondly, the tubes themselves, being short, will present a very unimpeded path to gas flow, helping get air through the fire when working hard. Both of which point to a very free-steaming boiler especially under load, though possibly one that is not of the ultimate efficiency in terms of extracting all the heat possible from the fire. But for what they were designed for - high power in a light machine - the boiler is ideal.

The following table shows the relative proportions of firebox, tubes and superheater on the Bulleid Pacifics and other comparable designs, from which it is notable how big the fireboxes are on the Bulleids (and, also even more noticeable, how small the superheaters were on the GWR designs!)

Firebox Tubes + flues Superheater
Bulleid WC/BB 9.5% 70.1% 20.4%
Bulleid MN 8.8% 69.8% 21.3%
Maunsell Schools 7.9% 78.3% 13.8%
Peppercorn A1 7.8% 70.6% 21.6%
Collett King 7.7% 79.8% 12.4%
Maunsell Lord Nelson 7.7% 76.3% 16.0%
Collett Castle 7.2% 79.7% 13.1%
BR "Duke of Gloucester" 7.1% 71.5% 21.4%
Gresley A4 7.0% 70.5% 22.5%
BR Britannia 6.6% 70.9% 22.5%
Stanier Duchess 6.3% 71.0% 22.7%

Incidentally, in answer to the question about welding, according to Bradley, it is the inner firebox that is welded, with the outer firebox and the barrel riveted. the inner and outer are welded to each other around the firehole door. Welding was reckoned to save about 1.5 tons relative to an equivalent riveted copper box. There was also a significant design change between the first ten Merchant Navies and all the subsequent boilers, in that in the originals, the first ring is parallel and the second ring is tapered on its underside (but flat along the top). In the later boilers, the first ring is tapered on its underside and the second parallel. The effect of this change is to reduce the weight of the boiler and - significantly - the weight of the water it contains, without changing the heating surface.

Tom

 

You cant really place the blame on the diesel fiasco on the steam engineers who took the decision to build a fleet of standard steam locos, including 71000, and rebuild the Bulleids. When the rebuilding decision was made steam was expected to last into the 80s if not the 90s. It was a political decision from above which prematurely decreed the end of steam and purchase of unproven diesel designs. Dont forget the same sort of thinking was behind the APT where proper railway engineering was almost ignored. It was the old fashioned railway engineers who saved the day with the HST