Double chimneys.

A head scratcher. Which was the first loco anywhere to be fitted with one?

 

I think some LNWR 4-4-0s had them.
Dave

 

I like the French double decker coaches in that link

 

Further down is a triple chimney Arthur.

 

Do Fairlies count?

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French compound Pacific No 3566 by Chapelon in 1929?

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One chimney per smokebox, disqualified

 

Webb LNWR 'Jubilee' compound No. 1502 was built in 1899 with a double blastpipe and chimney, but this was 'soon removed'. From 'A Compendium of LNWR Locomotives 1912 - 1949 Part 1, by Willie B Yeadon

 

On the threads about the 9th and 10th May Castle runs, there was some discussion of the difference between double-chimney and single-chimney locos.

Other things being equal, a double-chimney one should be a tad more powerful than a single-chimney one -- and the various more sophisticated exhaust systems such as Kylchap and Giesel should be a bit better than conventional blastpipes. This makes me wonder about the programmes of conversion to double chimneys in BR days. Why were some members of a class converted but some left with single chimneys? Was it just that they hadn't got round to converting some before mass withdrawal was in sight?

And what would be the pros and cons of further conversions now? How has the Bulleid with a Giesel ejector performed?

 

From what I remember, the Worth Valley reported an approximate 10% saving on coal, which corresponded roughly with BR's findings with 34064.

Richard.

 

There is a wealth of information available concerning locomotive exhaust systems. Describing Kylchap and Geisel as "a bit better than conventional" could almost come under the terms of being disingenuous. Any reduction in back pressure coupled with an improvement in steaming capacity gives an improvement that could not be referred to as a bit. The conversion of A3 Pacifics to double Kylchap was worth an extra 500hp.
The word "conventional" needs looking at in itself. For Chapelon, Porta, Vittone and others, their conventional had moved on. At home, all this work was carried out overseas and so could not possibly be of any value to the UK, an all too frequent occurrence. The good people of BR understood exhaust systems so well that they wanted to remove the double Kylchap systems from the A4s.
The Giesel ejector is not without flaws - read David Wardale - but the WC was felt to be the equivalent of a MN. Exhaust system design has moved on. Anything could be improved. but the changes involved would scarcely be preservation in the stricter sense, though changes could be reversed. It depends on what you demand of your traction. If it does the work you require at an agreeable cost, then fine. If not, in that case you have choices to make. With a new build you have a blank canvas but with existing types there are issues to be faced. Will the frames withstand the extra power? Will the "Photographers" accept the change in appearance? And so on.

 

The LNWR I think had the first, fitted to Black Prince in June 1897, and there is both an illustration and a drawing in An Illustrated History of LNWR Engines by Edward Talbot.

The only reason for a plain double chimney is (according to Dr. Tuplin) when you have insufficient height in the smokebox to put in a correctly draughted single chimney. They are thus only really needed on locos with large boilers.

I believe the reason for double chimneys being fitted on Kings and Castles was the change in the quality of the available coal, which required an increased draught.

I also seem to recall that BR's tests with the Giesel 9F produced no savings, they are extensively covered in the RCTS books on the Standards, so generally if there is a saving compared to a normally-draughted engine it simply indicates that the original draughting was less than optimal. In other words, to prove a saving that is genuinely due to the Giesel ejector and not simply because it frees up a loco suffering from excess back pressure or other consequences of a poorly designed blast-pipe, first you have to get the existing draughting working as well as you can - and without any extant test facilities such as Swindon or Rugby that is not easy. It's a pity the BR authorities were so blinkered about Kylchaps, since they had the proof of their success on their own railway.

The Kylchap, Kylpor and Lempor systems _do_ produce savings and/or more power, and there are several authorities that report the savings, from Peter Townend to David Wardale, and including of course the great Chapelon. Either you can use the extra power because you need it, or you can work the loco less hard for the same power. They do however require considerable experimental work to get the right settings for a given set of circumstances.

 

Part of the design ethos of the standards is that the Boilers would produce enough steam for the cylinders at low - medium firing rates ( per area of firegrate). They we re configured such that adequate draught would be provided at these medium rates of output using the latest research by Mr Ell of Swindon ( for open exhaust systems). The claim that the output with a correctly proportioned single chimney could be just as good as a double chimney was accepted on the basis of improvements applied to some poorly executed double chimneys - notably the Ivatt 4.
Best results in terms of performance ( as opposed to economy) we're often obtained from standards by virtue of a bit of 'thrashing' the potential being inherent in the design. Of the double chimney exmples the standard 4 come about as a requirement for regular higher performance on routes with restricted route ability. The 9F was already accepted as a good enough and my suspicion is that the Geisl company had lobbied for a trial by the front door and knowing that a trial was coming by hook or by crook the double chimney - which would giver closer results to the Geisl - was instigated. (so as not to be shown up by the hun). Of the other standards they all performed, after a bit of tweaking to their expected outputs ( which we're not high for their respective sizes) The trials we're also slanted towards economy and use of lower grade coal, not out and out maximum performance.
The other Geisl trial was a success on the BofB Pacific because a closed exhaust system is less prone to spark throwing than an open one, but the exhuast on that class was already a good fit so no massive performance increase was likely

The saga of 71000 with its cobbled together chimney rogue ashpan/ brick arch is well known - perhaps as a result of Swindon/Derby politics who knows but its interesting that the Eastern Region ( with its experience of 3 cylinder pacifics, caprotti valve gear and Kylchap exhausts) was never allowed to get its hands on it.

If the question is would any of the Standards Benefit from a double chimney the answer is 'probably not much' unless they were going mainline in which case the answer is ' Yes' and for the same reasons they would probably benefit from more sophisticated 'Closed' draughting systems which can deliver lower back pressures for a given smokebox vacuum.

 

Doncaster drawing office designed a double blastpipe and chimney for the Standard 4 2-6-4 tanks, with the intention of fitting the unit to the locos operating on the LT &S line. Presumably, this would have given the locos a bit more umph!
The double chimney, ejector exhaust ring and petticoat were the same as those used on the early LMS Ivatt 4 2-6-0s

 

Would this be the W.A. Tuplin who wrote in a book that the only reason the LNER dole chimney locos went ether is that drivers drove by ear so drove the locos harder until they made the same noise as a single chimney variant? With that level of genius I wouldn't put too much store in anything else he wrote.

 

I think talking about the Standards and Derby/Swindon ignoring Eastern Region experience is a little unfair, at the time making loco's easier to live with was a much higher priority than higher power output outright, the like of kylchap exhausts, conjugated valve gear etc were known to need much tinkering to get right and the running gear on Gresley Pacifics certainly suffered with less TLC during wartime, with that in recent memory, it's not hard to see why some were put off such improvements if they required much more man hours to get them working properly (the standards were initially meant as a stop gap until widespread electrification afterall).

Double chimneys on Castle/Kings and rebuilding Bulleid's were relatively simple modifications to make life better for crews and shed staff, trying out more idea's with Kylchap exhausts, insider cylinders on new types, different valve gear setups etc, would have meant more crawling between frames, modifications and experimentation etc at a time when there just wasn't the will to do it among many, conditions and idea's in the 1950's were somewhat different to the LNER of the late 30's and preservation where highly maintained, such idea's work extremely well.

Why mess with (say for example) a Standard 4, that works fine (if not an absolute beast of a machine) with half the TLC of a machine 25 years older ?.

 

Some interesting stuff on 'Fighter Command' here.

PS: Please get the spelling of Giesl correct!

 

Kylchap exhaust systems do require a little fine tuning. Where do you get the notion of constant tinkering from - the Swindon Handbook perhaps? The best choice of Goodfellow tips needs to be made and associated blast nozzle tip area. You just need to carry out good initial calculations and then carry some tests on the road. One locomotive and a few weeks. But in return you get a better steaming, more powerful locomotive which uses less fuel and is more forgiving of indifferent fuel quality. A locomotive that was easier to live with. As a shedmaster you soon discovered another advantage. The tubes needed less cleaning ditto the fire cleaning. Neither advantages to be considered worthwhile in the design offices of BR.

On the subject of LNER and TLC. Next time you are preparing a GW engine ignore the lubrication of the valve gear. Continue the experiment for a few weeks. See what happens. This essentially is what happened on the LNE. The conjugated gear was grease lubricated, which was fine when someone did it. Not so so good when it was neglected. Which it was, probably because perhaps you could on the odd occasion. I have some grease lubricated machines at my place of work. The grease cups do not need filling every day but they do need a refill from time to time. The wartime conditions produced just the right conditions for neglect to set in.

The post war conditions were not the best but fact remains that the Derby/Swindon axis had a great deal to learn and not just about exhaust systems.

 

One of the themes here is the need for stronger draught, not for performance sake but to mitigate the resistance caused by spark arrestors or 'self cleaning' screens Are spark arrestors not compulsory on todays mainline steam locomotives and at the very least adviseable on 'heritage railways' ?