A Coarse Guide to the Steam Locomotive for ‘N’ Gauge Modellers

[Newportnobby]

I travelled behind 'Scots Guardsman in 2012 from Preston to York and his performance was exemplary.

Preston


York

[Train Waiting]

A Coarse Guide to the Steam Locomotive for 'N' Gauge Modellers - Part 98


Hello Chums

The Final, Exhausting Section of Our Gloriously Brief Mini-Series

'Doubling Up - 2'

Although, as far as I'm aware, there was no especially scientific analysis involved - this was before Rugby Testing Station opened - the LMS locomotive engineers hit the 'sweet spot' the the draughting arrangements for the 'Princess Coronation' 'Pacifics' and the rebuilt 4-6-0s fitted with the magnificent 2A boiler. This instilled an enthusiasm for double chimneys amongst the LMS locomotive Engineers, including the Chief Mechanical Engineer, HG Ivatt (Mr Ivatt the Younger).

Let's start with the success. A pretty much guaranteed success at that. In 1946 they commenced rebuilding the 'Patriot' class 4-6-0s with the 2A boiler. Unlike the 'Converted Royal Scots' they were given Stanier-style side-window cabs and they were almost identical with the two rebuilt 'Jubilees' mentioned earlier. A bit less powerful than the 'Scots' - they had smaller cylinders - they were excellent performers on the road with lots 'N' lots of reserve in the boiler. However, the 'Royal Scots' were the priority and only 18 of the 52 'Patriots' were rebuilt.

In 1947, Mr Ivatt introduced a replacement for the venerable 'Fowler' '4F', beloved of JE Anderson and all the Midland Mafia who dominated locomotive matters for so long on the LMS. They had even talked Sir William Stanier into building 45 more for them between 1937 and 1941 (yes, they were still building '4Fs' in 1941!). Mr Ivatt put his foot down with a firm hand and a thoroughly modern 2-6-0 of power class '4F' was the result. They had the potential to be really good engines and 162 were built from 1947-1952. The BR 'Standard' '4' 2-6-0 was essentially the same design modified to look like the rest of the 'Standards'. One hundred and fifteen of these were built between 1952 and 1957.



[The first of the Ivatt '4F' 2-6-0s, No. 3000. An LMS Official photograph.]


Looking at the picturingham, it's difficult not to notice the massive double chimney. There were two blastpipes arranged in line but angled slightly to the front and rear respectively. Hence the massive casing. A wonderful idea in theory. In practice, the blighters would not steam. As mentioned earlier, use of this contraption was abandoned for new construction at the end of 1949. All the class built from 1950 had single chimneys, designed on SO Ell's principles. The first fifty all received single chimneys by 1956. Here's No. 43106 at Bridgnorth, contentedly minding her own business:





At the end of the LMS' life, Mr Ivatt embarked upon an extraordinary programme of modifications to the excellent Stanier 'Black Fives'. Construction of these engines continued into BR days. A few of these variants were given double chimneys. These fell into four groups:

44686/44687 Built 1951. The final Caprotti variant. Exceeding good engines.

44755-44757 Built 1948. The first Caprotti variant, three had double chimneys as well. Reputed to be little different from the single-chimney engines.

44765/44766 Built Crewe 1947. Two of the batch with Timkin roller bearings throughout and Walschaerts valve gear also had double chimneys. They performed well enough, although not hugely better than the similar single-chimney variants. The double chimney did appear to cause a problem with drifting smoke obscuring the driver's vision on occasion. I have seen a photograph of No. 44765 hard at work on Shap Bank in August 1966. This suggests these two engines reatained their double chimneys until withdrawal.

44767 Built 1947. The one-off! Timkin roller bearings throughout, outside Stephenson link motion and a double chimney. The double chimney didn't seem to suit this engine and was replaced by a single chimney in 1953. After that the locomotive acquired a great reputation for power and reliability, and achieved some of the highest annual mileages run by any of the class. Unusually for a one-off she was long-lived, being withdrawn in December 1967 and is, happily, preserved.

The 'Black Fives', essentially a design based on GWR practice, had been good steamers from their introduction and the double chimney experiments did not provide any great benefit, with the possible exception of the Caprotti-fitted examples.

I think it is fair to say, based on LMS experience, that double blastpipes and chimneys were not necessary on locomotives up to and including BR power class '5'. At the higher steaming rates likely to be required above BR power class '5', they provided a definite advantage as, hopefully, I have shown.

In the next part of this gloriously brief mini-series we'll discuss the use of double chimneys for the BR 'Standards'.

Once again, many thanks to @martyn for reviewing and kindly commenting on the draft.


'N' Gauge is Such Fun!

Many thanks for looking and all best wishes.

Cheerio!

John

[port perran]

So that's what the original Bulleid Light Pacifics looked like with their boiler casing removed.
34106 was, of course, named Lydford 

Sorry John, @Train Waiting , I couldn't resist.

Sorry to interjest (sic) on your most excellent postingham.

[Train Waiting]

A Coarse Guide to the Steam Locomotive for 'N' Gauge Modellers - Part 99


Hello Chums

The Final, Exhausting Section of Our Gloriously Brief Mini-Series

'Doubling Up - 3'

Nationalisation of the railways occurred in 1948 and RA Riddles, formerly of the LMS, was appointed Railway Executive Member for Mechanical and Electrical Engineering. Once Mr Ivatt the Younger's deputy on the LMS, Mr Riddles had 'leapfrogged' him on return from Government service during the War. Mr Riddles appeared to have friends in high places on the LMS. In my view, Mr Ivatt would have been a better choice. Mr Riddles' Locomotive Engineering team had a distinct LMS bias and ES Cox was in charge of design. It was intended to produce a range of BR 'Standard' steam locomotives.

Now, I made a slightly controversial point earlier about there being a sting in the tail related to Sam Ell's brilliant work at Swindon on draughting. He achieved extraordinary improvements in steam production for several classes. This, rightly, attracted a great deal of attention.

Here is the quote that, hopefully, proves my point:

'Prior to Ell's work, it had been proposed to fit the larger standard engines with double chimneys as Plate 24 portrays, but this was based upon previous LMS experience where this arrangement had shown marginally more favourable results on the 'Duchess' Pacifics and the Class 5 mixed traffics. However, Ell was able to show the way to better results with correctly proportioned single chimneys than had been obtained formerly with some of the double arrangements, and it was decided to initiate the new series with the simple single arrangement leaving future development work any trend to multiple nozzles at a later date.'¹

Plate 24, from a BR illustration, mentioned in the quote is interesting - a double chimney 'Britannia' with bar frames:





I think the late Mr Cox's quote is fascinating. That use of 'marginally' might have been fair enough for the 'Black Fives', but surely the results of the 1939 trials showed more than a marginal improvement for the 'Princess Coronations' ('Duchesses'). And the quote completely ignores the magnificent '2A' boiler, with double blastpipe and chimney, which transformed any LMS 4-6-0 to which it was fitted. Yes, the 'Princess Coronations' performance in the 1948 Locomotive Exchanges was less than could have been expected but the 'Converted Royal Scots' set the rails on fire (metaphorically!).

Anyway, the BR 'Standards' were to be built with single chimneys. The exception was the sole '8P' Duke of Gloucester. Then, in September 1958, '9F' No. 92178 was turned out from Swindon Works with a double chimney. Her performance was such an immediate success that all new engines from No. 92183 were similarly equipped. Double-chimney '9Fs' were especially popular on passenger work. Some enginemen preferred them to a 'Britannia', finding them both freer steamers and better riding at speed. What a shame no 'Britannias' were fitted with a double chimney.

Then, in 1961, five earlier members of the class were rebuilt with double chimneys (Nos. 92000/1/2/6/79). Some of these saw much use on the Somerset & Dorset (S&D). The years 1960-62 were glorious ones on the S&D with double-chimney '9Fs' in charge of much of the summer traffic. No. 92220 Evening Star worked the last 'Pines Express' over the S&D on 8 September 1962. Nos 92220/4 were at Bath Green Park briefly in 1963 and that was that - the line was left wither away and its '9F' era was over. Such a shame.

I have found a good quote about the wonders of the double-chimney '9Fs':

'For a friend, then working at King's Cross, and his Driver - well used to working on New England's '9F's - the change was dramatic, and initially, puzzling. Given an almost new No. 92183 to find and prepare in the dark ready for a fish working, they noticed nothing unusual until they got out on the road. Then they found that they had something special and altogether different from the '9Fs' they had experienced before. They reckoned that the effortless power and much freer steaming produced something that was truly brilliant. Once on shed at the end of the journey, they found to their surprise that the locomotive had a double blastpipe and chimney and all was explained.² 

There's no doubt the double-chimney 'Nine' was an exceeding good engine and, I'd argue, the best of the 'Standards'. Yet, ES Cox devotes a single sentence [partly!] to them in his British Railways Standard Steam Locomotives:

'Apart from the above, a number of locomotives were fitted with straight forward double chimneys and blastpipes - No. 71000 as already mentioned, 80 of the Class 9 2-10-0s [...]'

As for the fiasco of the Franco-Crosti locomotives - five pages, with more in a later chapter. And there was a mystery amongst the 'Standards'. Mr Cox's sentence continues:

'[...] and, at a later stage, all of the Class 4 4-6-0s allocated to the Southern Region and some of these on the Western Region were altered to take the double arrangement.'

Mr Cox went on to bemoan the fact that Swindon and Eastleigh Works produced different-shaped castings for the double chimneys. He didn't like the Swindon version.




[The Swindon double chimney as fitted to No. 75029. [British Railways photograph]
Please forgive the missing rear of the tender. Whilst this would be typical of my coarse photography, it's actually from the original print. By the way, No. 75029 is, happily, still with us, complete with double chimney. She's on the NYMR and requiring a major overhaul - there's a public appeal open. She was purchased from BR by the late David Shepherd and given the name The Green Knight.]


One wonders why, with all of Sam Ell's know-how, a double chimney was fitted to locomotives of only BR power class '4'. It was found, in single-chimney form, these engines could evaporate 19,600 lb. of water per hour. The double chimney increased this to 22,400 lb. of water per hour. This is an interesting contradiction of the results of Mr Ell's earlier work which implied a properly designed single blastpipe and chimney was the equal of a double arrangement. 

This concludes our discussion of conventional double blastpipes and chimneys. I intend to conclude our ambitiously brief mini-series with a discussion of three of the more exotic arrangements. We'll commence, in the next part, by looking at a New Zealander's adaptation of a Belgian engineer's system. Sounds like such fun!

Once again, SuperSpecial thanks to @martyn for reviewing and commenting on the draft.
 

¹ ES Cox, British Railways Standard Steam Locomotives, Ian Allan. London, 1966, Page 80. Plate 24 is between pages 64 and 65.

² Mike Romans, writing in the Introduction to Locomotives Illustrated, No. 75, Ian Allan, Shepperton, 1991, Page 4.

³ ES Cox, British Railways Standard Steam Locomotives, Ian Allan. London, 1966, Page 119.


'N' Gauge is Such Fun!

Many thanks for looking and all best wishes.

Tickety-tonk

John

[Southerngooner]

What a wonderfully, truly spiffing, tale, very well told. I'm so glad @martyn put me onto this, and I'm now bang up to date and SO much better informed.

Many thanks for all your hard work

Dave

[Papyrus]

Blimey! I've been away from the forum for a week or more (pressure of retirement, doncha know...) and I had a lot of catching up to do. Just so much information there, my poor fading brain cell couldn't cope. I am once again indebted to John and Martyn for shining a light into the stygian gloom of my ignorance. I have learned so much and I can nearly understand some of it. I shall be very sorry when you write "The End". Once again, thank you very much.

All the best,

Chris

[Train Waiting]

What a wonderfully, truly spiffing, tale, very well told. I'm so glad @martyn put me onto this, and I'm now bang up to date and SO much better informed.

Many thanks for all your hard work

Dave

Thank you very much, Dave. I must gratefully acknowledge the mini-series would be enormously diminished without all the help from @martyn @Hailstone and Ted. They have saved me from many self-inflicted embarrassments.

It's nice to hear you have found it informative. My primary purpose is to entertain and, if it's informative as well, so much the better.  Thank you.

**

Blimey! I've been away from the forum for a week or more (pressure of retirement, doncha know...) and I had a lot of catching up to do. Just so much information there, my poor fading brain cell couldn't cope. I am once again indebted to John and Martyn for shining a light into the stygian gloom of my ignorance. I have learned so much and I can nearly understand some of it. I shall be very sorry when you write "The End". Once again, thank you very much.

All the best,

Chris

Thank you very much, Chris. We are fast approaching 'The End'. You'll know when we get there because, typical of my SuperSilly approach, I intend to finnish with a Finn.


Thanks again, chaps, and all good wishes.

John

[Bealman]

At this late point I'd like to echo the quotes from @Southerngooner and @Papyrus above.

What a wonderfully educational series! 

[Train Waiting]

A Coarse Guide to the Steam Locomotive for 'N' Gauge Modellers - Part 100


Hello Chums

The Final, Exhausting Section of Our Gloriously Brief Mini-Series

'Multiple Jets - Lemaître'

I feel we have been ignoring the Southern for a while so time to make amends. REL Maunsell, formerly of the South Eastern & Chatham Railway was appointed Chief Mechanical Engineer of the Southern. He retired at the end of October 1937 and was succeeded by OVS Bulleid from the LNER.

Mr Maunsell introduced three principal modern express passenger classes. The 'King Arthurs' of 1925, 54 of which were built. The 20 Urie 'N15s' of 1918 were modified and incorporated into the 'King Arthur' class. The two-cylinder 'Arthurs' were straightforward,  dependable engines capable of good performances.

The first four-cylinder 'Lord Nelson' 4-6-0 was introduced in 1926, with another 15 appearing in 1928/29. These were big, powerful engines with, unusually, their cranks set to give eight exhaust beats per revolution of the driving wheels. The 'Nelsons' had something of a mixed reputation. There were only 16 so the enginemen didn't get many opportunities to work on them. It has been suggested that the fireman struggled with the shape of the grate to the detriment of steaming. Some enginemen stated openly they would prefer an 'Arthur' to the more powerful 'Nelson'. Mr Maunsell and his team made a series of modifications to members of the class, one of which we'll return to in a later part of this ultra-brief mini-series.

Then, in 1930, came Mr Maunsell's legendary 'Schools' three-cylinder 4-4-0. Intended for secondary passenger work and for use over routes with severe restrictions. Comprised of as many parts from 'King Arthur' and 'Lord Nelson' classes as possible, the 'Schools' were exceedingly good engines. Forty were built and the enginemen loved them. They were powerful, good steamers and capable of performances more in line with what would have been expected from 4-6-0s. They were used on prestige trains such as the pre-War Bournemouth expresses.

Taking over from Mr Maunsell, Mr Bulleid decided, after extensive riding on their footplates, to do something about the 'Nelsons'. He instructed Eastleigh to design new cylinders with 10 in. diameter piston valves instead of 8 in. and with improved steam and exhaust passages. All but two of the class were fitted with these new cylinders.

More pressing was the draughting. Mr Bulleid was certain it could be improved - but how.

'Twas a Belgian engineer who provided the answer - not for the first time in this mini-series. The chap's name was Maurice Lemaître. Mr Bulleid simplified [now there's a phrase I never expected to write] the Lemaître exhaust. He retained the multiple nozzles, arranged in a circle, but discarded the central jet ant its poire réglable, a device which enabled the driver to sharpen the blast by partly or totally closing the central jet. Another variant of the variable blastpipes we discussed earlier.

Nothing if not meticulous, Mr Bulleid arranged for a series of 17 experiments to determine the final arrangement of five nozzles of 2 5/8 in. diameter and with the chimney choke increased from 15 in. to 25 in. diameter. This resulted in the very large diameter chimney associated with the Lemaître exhaust.

As a priority, all of the 'Nelsons' received the Lemaître exhaust, improving their steaming and performance. So did 20 of the 40 'Schools' class to rather lesser effect.

Five of the 'Urie Arthurs' and one of the 'Maunsell Arthurs' also received a Lemaître exhaust. I enjoy the names of this class, so here's the six engines:

No. 736 Excalibur
No. 737 King Uther
No. 741 Joyous Gard
No. 752 Linette
No. 755 The Red Knight
No. 792 Sir Hervis de Revel

Seeing No. 741 on the list gives an agreeable opporchancity to repeat the story about an ASLEF union official remonstrating with Mr Maunsell regarding the engine's name: "'Ere, Guv, what about the bleeding driver?"

The 'Arthurs' with the Lemaître exhaust turned out to be exceptional performers and it was intended to fit further members of the class. Like the 'Schools', Wartime conditions prevented this.

The twenty 'Q' class 0-6-0s, designed by Mr Maunsell, but built after his retirement, could be shy for steam when used on main-line work. All received Lemaître exhausts which helped considerably.

Mr Bulleid fitted the Lemaître exhaust to his three new designs for the Southern - the 'Q1' 0-6-0, 'MN' 4-6-2 and 'WC/BB' 4-6-2. The 'Pacifics' that were rebuilt by BR retained the Lemaître exhaust and consequent large diameter chimney, seen to good effect in this picturingham of 602 Squadron:




[I love this ProperlyPoole Graham Farish model, borrowed from the SuperSilly train set for the picturingham. It's full of character and reminds me of the delightful Hornby-Dublo Barnstaple (2-rail) and Dorchester (3-rail).]


The boilers used on Bulleid 'Pacifics' were prodigious steamers - a combination of good design, thermic syphons in the firebox and Lemaître exhaust. Let's, courtesy of a BR Official photograph, have a peek inside a 'Pacific's' smokebox at Mr Bulleid's modified Lemaître exhaust:





The two pipes entering the chimney petticoat are exhausts for the brake ejector and the turbo-generator - the Bulleid 'Pacifics' had electric lighting. There is a ring of blower jets, provided with steam through the small pipe seen at the right, at the base of the blastpipes.

Not withstanding the success of his applications of the Lemaître exhaust, Mr Bulleid's restless mind was not completely satisfied as can be seen in this quote from his son, HAV Bulleid:

'In repeating his 'Nelson' success by fitting a simplified Lemaître multi-jet exhaust with five 2 5/8 in. diameter nozzles and a 29 in. chimney with 25 in. choke, Bulleid always said there was room for further improvements in the exhaust system. He was proved right by the Giesl trial in 1962.'¹

Which is as good a trailer as any for the next part. This time we met a Belgian and a New Zealander (Mr Bulleid); next time we'll meet an Austrian with a rather splendid name.

SuperSpecial thanks to @martyn for reviewing and commenting on my draft postington.

¹ HAV Bulleid, Bulleid of the Southern, Ian Allan, London, 1977, Page 54.


'N' Gauge is Such Fun!

Many thanks for looking and all best wishes.

Cheerie-B

John

[Newportnobby]

At the very least, top marks for the correct spelling of Oliver's surname, John.
Chapeau

[Train Waiting]

At the very least, top marks for the correct spelling of Oliver's surname, John.

Thank you, Mick.

Bulleid to rhyme with 'succeed'.

I've lost count of the number of times I've seen 'Nielson & Co' in print. I've seen 'Bullied' a few times.

Anent pronunciation, Mr Bulleid's predecessor on the Southern can catch one out. Maunsell, pronounced 'Mansell'.

Thanks again and all the very best.

John   

[chrism]

Anent pronunciation, Mr Bulleid's predecessor on the Southern can catch one out. Maunsell, pronounced 'Mansell'.

Ah, now that's one I didn't know.

That makes it even riper for confusion since the earlier carriage and loco superintendent of the SER was also named Mansell, and also forenamed Richard - primarily known for his composite carriage wheels.

[Train Waiting]

A Coarse Guide to the Steam Locomotive for 'N' Gauge Modellers - Part 101


Hello Chums

The Final, Exhausting Section of Our Gloriously Brief Mini-Series

'Multiple Jets - Giesl'

One thing this threadingham really enjoys is a good name and I think this one is the best yet - Dr Adolf Giesl-Gieslingen of Vienna. Dr Giesl had invented the Giesl ejector, a particularly sophisticated 'long and thin' version of the multi-jet blastpipe. The picturingham, from the Talyllyn Railway Preservation Society, shows Dr Giesl at Pendre Works in 1958 with the ejector about to be fitted to Talyllyn Railway No. 4 Edward Thomas:





Here's two views about the Giesl ejector, first LTC Rolt:

'The Giesl ejector has been an outstanding success, improving the locomotive [Talyllyn Railway No. 4 Edward Thomas] greatly both in performance and fuel economy. It has been called "the greatest improvement in the steam locomotive since the superheater" and thousands have since been produced for European railways, particularly those east of the Iron Curtain, as well as for South Africa, India and Australia. In Britain it has since been adopted by the National Coal Board, but British Railways have remained unconvinced despite the overwhelming weight of contrary opinion.'¹

And now for Dr WA Tuplin:

'No such artifice [multiple exhaust] ever showed any perceptible advantage over the plain blast-pipe and chimney ideally designed for the conditions but of course, it might and sometimes did show advantage over a badly designed version of the conventional scheme.

One such artifice  (the Giesl ejector) did, however, have an advantage of a quite different kind. Its nozzle and chimney were only a few inches wide and so it minimised obstruction to the recurrent operation of cleaning tubes. Very regrettably, British Railways, against all the protestations of the technical staff who were quite clear on the matter, were misguided into spending taxpayers' money on comparative teats on a two-cylinder 2-10-0 of class 9 in the vain hope of disproving French and German findings that the advantage of the Giesl ejector over a properly designed double chimney was too uncertain to be worth bothering about.'²

Interesting. I wonder which author was correct. Let's look at the evidence.

Neither the SNCF nor the DB, both of which used steam traction for longer than BR, adopted the Giesl ejector.

The NCB used it, albeit not on a massive scale. As an example, at the Waterside system in Ayrshire, Andrew Barclay 0-6-0T No. 17 (AB 1338/1913) was a good-steaming and powerful engine. In 1953, the National Coal Board invested in a new Barclay 0-6-0T (AB 2335/1953) to share duties with the veteran. She was given the number 24. It turned out she was rather a disappointment because, surprisingly, she wouldn't steam. Fitting a Giesl ejector cured her.

Let's look at what happened on BR. Dr Tuplin mentions only part of the story.

In 1957 Roland Bond, then Chief Mechanical Engineer of British Railways, was approached regarding a trial of the Giesl ejector on a '9F' - these were still being built at the time. Mr Bond declined, but Dr Giesl's supporters in this country had friends in high places and Sir Brian Robertson, Chairman of the British Transport Commission, instructed that the trial must take place. The deciding factor appears to be that the Giesl ejector would permit the use of low grade small coal of which the National Coal Board (NCB) had a surplus for which it was, apparently, keen to find a use.

The engine chosen was No. 92250, the last '9F' built at Crewe (and the highest-numbered), then only a few months old. She was, of course, fitted with a double chimney. Trials at Rugby Testing Station were carried out over four months in 1959, in as-built double-chimney form and with a Giesl ejector fitted. Dr Giesl was present as was a firing instructor from the Austrian Railways.




[A BR schematic of the Giesl ejector used in the trials. Typical of these devices, it had seven jets, arranged in line in a slight fan shape, which required a long and thin oblong chimney. It used the principle of multiple exhaust nozzles having a greater ejector effect on hot gasses issuing from the tube ends for a given volume of exhaust steam. It produced a stronger draught for a given exhaust pressure, which allowed for a reduced back pressure in the cylinders.]
 

The result, with good Blidworth coal, was a saving in coal consumption of 4%. The Giesl ejector also, due to very low back pressure, permitted an increase in indicated horsepower in the range of 3.5% - 5.1%.

The Giesl-fitted locomotive was able to burn certain types of low-quality coal, but with an increase in coal consumption of 19%.

From this, it's clear that the Giesl ejector did what was claimed of it. The 4% improvement in strict test conditions was insufficient to persuade BR to fit the ejector to locomotives in the rough-and-tumble of daily service.

As for the ability to burn lower-grade coal, the price quoted by the NCB was insufficient to cover the higher coal consumption and provide the 7 1/2% cost saving upon which the trial had been predicated.

Of course, had a different class of locomotive been used for the test, perhaps a 'Britannia' or a 'Jubilee', the results might have been very different as the double-chimney 'Nine' was an exceedingly efficient engine.

Let's have a couple of quotes from ES Cox who was much involved with the trials:

'[...] Dr Giesl himself, a delightfully fair minded man, devoted to steam traction, and a first rate engineer.'

'There was thus no case for the adoption of the device in this particular field, and although naturally disappointed, Dr Giesl accepted with good grace the situation, which indeed was self evident. Not so however those who had sponsored his invention in this country, and had hoped to see wide scale adoption. I am indeed sorry to say there was a rather acrimonious outcome.'³

No. 92250 retained the Giesl ejector until she was withdrawn in December 1965. Let's conclude with a quote from Mike Romans' perceptive Introduction to Locomotives Illustrated No. 75:

'The Giesl-equipped example was something of an enigma and the conversion never lived up to its inventor's claims in official trials. It is generally suggested that the '9F' was too well draughted to gain any advantage from the theoretical benefits of the ejector. The views of the men who worked on her, particularly fireman, are so mixed that it is difficult to gain an objective conclusion from that source. Though one or two reckoned it the best '92' the more common view was that it was nothing special, though a small minority rated it worse than the double-chimney version.⁴

One could be easily for given for assuming this was the end of the line for the Giesl ejector on BR. The quote from Dr Tuplin suggests as much. But, it wasn't.

Three years later, another one was fitted. 'West Country' 4-6-2 No. 34064, still in original condition, didn't lack power or steaming ability. But, like her classmates, she was an inveterate spark thrower. This wasn't as much of a problem then as it is now, due to vastly better lineside vegetation control. I'm old enough to remember the controlled burning of railway embankments and cuttings.

In order to curb the Bulleid 'Pacifics'' propensity for throwing live embers when working hard, especially on the banks of the West of England main line, there had been experiments with wire-mesh spark arrestors but, due to the dimensions of the Lemaître exhaust, it was impractical to fit a suitable spark arrestor in the smokebox. Then they remembered the Giesl ejector.

On 31 January 1962 the Locomotive Drawing Office issued drawings and the necessary parts had been ordered from Austria. These arrived in time to be fitted to No. 34064 Fighter Command which was being given a general overhaul in April 1962. Dr Giesl visited Eastleigh Works to supervise the installation. The shape of the ejector permitted a small spark arrestor to be fitted between the nozzles and the chimney.

The modification was a complete success. Unfortunately, it was too late. JF Harrison, Chief Mechanical & Electrical Engineer, declined a request to fit another fifty light 'Pacifics' with Giesl ejectors. In late 1962 Eastleigh had ceased general repairs to the Bulleid 'Pacifics' and the first withdrawal took place in 1963. [No. 34055 Fighter Pilot].

No. 34064 kept her Giesl ejector until she was withdrawn in 1966. Apart from stopping the fire-throwing, the Giesl ejector reduced cylinder back pressure which caused an increase in power output. So much so that some of the South Western drivers regarded her as the equal of a 'Merchant Navy'! Mr Bulleid was correct in his view that there was room for further improvements in his 'Pacifics'' exhaust system.

***

So who was correct, Mr Rolt or Dr Tuplin? I think both were, although Dr Tuplin failed to mention the success with No. 34064. Although the Giesl ejector showed little advantage over a tip-top conventional double-chimney application, even by the mid-1950s there weren't that many of these. Many classes had inadequate arrangements. Draughting was, in my view, the last piece of unfinished business in British steam locomotive development. Hopefully, the last few postingtons have demonstrated this.

The Giesl ejector provided a fairly easy way to improve the draughting of locomotives where this was less than perfect with resulting poor or inconsistent steaming. In addition, it reduced cylinder back pressure which provided more power, probably more important for locomotives on faster duties. If only the BR '9F' experiment had been five years earlier and with a 'Britannia', 'Jubilee' or 'V2', history might have been rather different.

We are staggering to the end of this fabulously brief mini series. Next time, we'll discuss the Kylchap exhaust.

I'm hugely obliged to @martyn for reviewing the draft and entering into a particularly helpful correspondence. Once again, he has saved my blushes. Thank you, Martyn.


'N' Gauge is Such Fun!

Many thanks for looking and all best wishes.

Tickety-tonk

John

¹ LTC Rolt (Ed), Talyllyn Century, 1965, included in the combined Talyllyn Adventure, David & Charles, Newton Abbot, 1971, Page 252.

² WA Tuplin, British Steam Since 1900, David & Charles, Newton Abbot, 1969, Page 65.

³ ES Cox, Locomotive Panorama, Volume 2, Ian Allan, London, 1966, Page 99.

⁴ Mike Romans in Introduction to Locomotives Illustrated 75 BR '9F' 2-10-0s, Ian Allan, Shepperton, 1991, Page 5.

[port perran]

Thanks John.
I've  often wondered about the Giesl Ejector and what it was. Now I know.

Incidentally, I too remmber the controlled burning of lineside vegetation known locally in Wiltshire as "burning the batters".

PS I seem to remember Ian Allen ABCs referring to the Giesl Ejector  as Giesl Oblong Ejector.

[class8mikado]

And of course the story continued with 'the Volcano' aka City of Wells. Think its rather sad that BR Pulled out all the stops to design a reasonably well proportioned double chimney for the 9f- a locomotive that steamed well enough- seemingly to diminish the case of the Geisl Lobby- but cobbled one together from existing bits for 71000.

Fascinating though it is to have 'this exhaust is better than that /single better than double' argument the salient point is that a correctly proportioned and arranged Single chimney is often better than a  'bolted on with no regard to what its bolted on to' 'brand' of exhaust system... the worrying thing is even Mr Ell and co. were only just getting the hang of this in the 1950's.  and Mr Bulleid was busy bolting on 'one size Fits all'  multijets on engines right upto the point he took his bat off to Ireland.

The next point up the ladder is that a correctly arranged and propotioned Multijet is invariably superior to a single jet in one aspect or another.  Even to this day when the basic theory needed to proportion multijet exhaust systems is in the public domain ( i would say its not rocket science but it is sort of) to enable good steaming even with potentially debilitating spark arrestors... the take up is the exception rather than the rule...