Benefits of Double Chimneys?

[Gibbo675]

 For a perfect account of this by a time served railwayman of broad experience, Dick Hardy on a Midland driver attempting to drive a Kylchap A4 as he would handle a Black 5, one and a half turns up and the regulator part open, and getting nowhere while nearly killing the fireman. (I think in 'Railways in the Blood' but not in a position to check.)

 

Considerable training - in the UK system by long exposure through footplate grades to build experience - was required to make the different design approaches to steam locomotion work optimally. The French system of formal academic training for both firemen and drivers makes an interesting contrast for any prepared to look at it.

Hi 34...BD,

 

I was fortunate enough to have spent some time with Dick Hardy some years back while on some jobs out of Fenchurch Steet and what a super chap he really is/was (is he still breathing?). I had a great time picking his brain for all the things I needed to know about the how, why, what, where and when of all thing locomotive. He was very interested in that I had spoken about methods of drifting that would not damage the engine by not allowing the motion to run loose when not under power and also not draw exhaust gasses into the cylinders and valve chests.

 

He was also very interested in what I had done with 34067's valve gear and how I had worked out the front and back dead centres and applied the heat allowances to the settings of the valves

 

Your last point is one that I would, along with Mr Hardy, have to fully support, the French System produced the best locomotive enginemen in the world by quite some margin. He spoke at length about his experience of an exchange trip to France during his time on the Southern and that the French could not believe the carry on in Britain where engineers were graded below drivers and that drivers took what was randomly allocated to them often along with different firemen.

 

Gibbo.

[Phil Bullock]

Hi 34...BD,

 

I was fortunate enough to have spent some time with Dick Hardy some years back while on some jobs out of Fenchurch Steet and what a super chap he really is/was (is he still breathing?). I had a great time picking his brain for all the things I needed to know about the how, why, what, where and when of all thing locomotive. He was very interested in that I had spoken about methods of drifting that would not damage the engine by not allowing the motion to run loose when not under power and also not draw exhaust gasses into the cylinders and valve chests.

 

He was also very interested in what I had done with 34067's valve gear and how I had worked out the front and back dead centres and applied the heat allowances to the settings of the valves

 

Your last point is one that I would, along with Mr Hardy, have to fully support, the French System produced the best locomotive enginemen in the world by quite some margin. He spoke at length about his experience of an exchange trip to France during his time on the Southern and that the French could not believe the carry on in Britain where engineers were graded below drivers and that drivers took what was randomly allocated to them often along with different firemen.

 

Gibbo.

 

And yet according to Peter Smith Baron Vuillett was mightly impressed with the enginemanship and power output when he rode 92000 on the S&D.....

 

Phil

[Gibbo675]

And yet according to Peter Smith Baron Vuillett was mightly impressed with the enginemanship and power output when he rode 92000 on the S&D.....

 

Phil

Hi Phil,

 

I have been with 45407 between Crewe and Carlise via Blackburn and the Midland with Crewe men that blamed the world and his dog for the locomotives poor performance over that route and yet after only fire cleaning, a quick oil round and top up of water the very same locomotive ran like the wind back to Crewe with Carlise men on board (Gordon Hodgeson driving and Paul Kane firing).

 

I could explain why this was the case but I shall not do so for it is not my place to tell "too much truth" and leave it for you to guess the reason from who is named and who was not.

 

Gibbo.

[mcowgill]

I was fortunate enough to have spent some time with Dick Hardy some years back while on some jobs out of Fenchurch Steet and what a super chap he really is/was (is he still breathing?).

 

Sadly Dick passed away early this year. aged 94.  70013 worked a charter down the GEML a week or so later carrying a wreath on the smokebox door.

 

Martin

[Gibbo675]

Sadly Dick passed away early this year. aged 94.  70013 worked a charter down the GEML a week or so later carrying a wreath on the smokebox door.

 

Martin

Hi Martin,

 

I'm out of the big railway game these days and so didn't know. Many thanks for the news as it is all the same.

 

Gibbo.

[asmay2002]

 I've always thought it slightly odd that no trials were ever made (AFAIK) using them on either LMS or BR Class 5MT locos, given that 5XP Jubilees did get them. 

Some of the later black fives were built with double chimneys. 44765-44767, 44755-44757 and 44686/7, 44767 lost its in 1953 but the others all kept theirs.

 

 

 The LMS thought that sticking double chimneys on Ivatt 4mt 2-6-0s would increase their power output. Biggest disaster ever!

 

The Ivatt 4MTs had a very weird deisgn of double chimney with the two blast pipes sloping fore and aft unlike anything else ever used anywhere.  Whether a more conventional double chimney would have made a difference is unknown.

 

 So how was it that firemen on wide firebox designs with 40 to 50 sq ft grates managed day in day out on the LMS and LNER routes? There were incidents on both A4s and Princess Coronations on up runs when conditions were adverse (headwind, high demand for steam heat) that bunkers of 9 to 10 ton capacity - larger than on any 9F - were emptied well short of London. Better men?

For the most part the locos were worked at nowhere near the limit of what they were capable of mechanically. Firemen could work harder for short periods but the timetables didn't demand it. If they had been they would have burned way more than 10 tons of coal. In the book "The LMS Duchesses" there is a theoretical piece on what would have been needed for sustained high power on the WCML to take the loco much closer to its limits.  A stoker equipped tender with 14 tons of coal and 5400 galls of water would have been necessary.

 

Possibly better riding engines; a 3 or 4 cylinder pacific with 6'8" or 6'10" wheels rides better and delivers power more smoothly than a 2 cyl 2-10-0 with 5' wheels. 

The 9Fs were almost notoriously good riding engines - hence the 90MPH speeds recorded on occasions with them.

Edited October 6, 2018 by asmay2002

[manna]

G'Day Folks.

 

T go to the other end of the spectrum, a Deltic had two exhaust ports and 36 cylinders !

 

manna

[Dunsignalling]

And yet according to Peter Smith Baron Vuillett was mightly impressed with the enginemanship and power output when he rode 92000 on the S&D.....

 

Phil

Good, well-prepared loco, good driver, good fireman, all coming together on the day. In the UK, other than under exceptional circumstances, that was usually a matter of sheer luck; if any of the factors was "off" the performance would be too.

 

The purpose of the French way was to ensure those circumstances applied every day, on nearly every train. 

 

John

[The Johnster]

Some of the later black fives were built with double chimneys. 44765-44767, 44755-44757 and 44686/7, 44767 lost its in 1953 but the others all kept theirs.

 

 

 

The Ivatt 4MTs had a very weird deisgn of double chimney with the two blask pipes sloping fore and aft unlike anything else ever used anywhere.  Whether a more conventional double chimney would have made a difference is unknown.

 

For the most part the locos were worked at nowhere near the limit of what they were capable of mechanically. Firemen could work harder for short periods but the timetables didn't demand it. If they had been they would have burned way more than 10 tons of coal. In the book "The LMS Duchesses" there is a theoretical piece on what would have been needed for sustained high power on the WCML to take the loco much closer to its limits.  A stoker equipped tender with 14 tons of coal and 5400 galls of water would have been necessary.

 

The 9Fs were almost notoriously good riding engines - hence the 90MPH speeds recorded on occasions with them.

 

They were not bad riders for 2 cylinder 10 coupled engines with only one leading axle, but pacifics can ride like Pullmans.  The 90 mph stories are all concerned with making up time on locos which had replaced failures, a situation in which a crew willing to do their best would tolerate conditions which would not be acceptable in day to day service, and about which the Per Way people would have had something to say!  Evening Star's brief career at Canton on the 'Red Dragon' was on a timetable that required slogging with 16 coaches more than out and out speed, and she was brand new and riding at her best!

[asmay2002]

They were not bad riders for 2 cylinder 10 coupled engines with only one leading axle, but pacifics can ride like Pullmans.  The 90 mph stories are all concerned with making up time on locos which had replaced failures, a situation in which a crew willing to do their best would tolerate conditions which would not be acceptable in day to day service, and about which the Per Way people would have had something to say!  Evening Star's brief career at Canton on the 'Red Dragon' was on a timetable that required slogging with 16 coaches more than out and out speed, and she was brand new and riding at her best!

I'll quote Phillip Atkins here from "The British Raiwlays Standard 9F 2-10-0" page 48.

 

"A contributory factor here could well have been the exceptionally rigid frame structure of the 2-10-0 whose smooth riding qualities at speed were remarkable, something which could certainly not be said for the 4-6-2". (This was in the context of comparison of two runs, one by a 9F, the other by a Britannia over the same line).  It is fairly obvious that if the 9Fs didn't ride very well at speed the crews would simply not have gone fast with them.  They certainly didn't with other freight types substituting on passenger workings. No crew will push an engine to the point where they feel unsafe.

Edited October 6, 2018 by asmay2002

[The Johnster]

Agreed, but that's in relation to 2 cylinder Britannia pacifics, not A4s or Duchesses.  Canton men I spoke to in the 70s reckoned that Castles were a better ride than the Britannias, and held that the 4 cylinder layout was responsible.  Brits were considered stronger engines, but Castles were claimed to ride better and be capable of higher speed; this makes sense given the difference in driving wheel diameter.  

[LMS2968]

The Britannias were not particularly good riding engines, especially for a Pacific. There was a heavy vibration came up through the floor emanating from the trailing truck, which was very tiring. The surge from the two-cylinder layout also lent a certain roughness.

 

The 9Fs on the other hand rode like a coach. I spoke to many men who were not keen on the 9Fs; they were too big for most of the work, for one thing, and they always preferred an 8F. But all admitted that they were a very comfortable engine as far as ride quality was concerned.

[kevinlms]

Good, well-prepared loco, good driver, good fireman, all coming together on the day. In the UK, other than under exceptional circumstances, that was usually a matter of sheer luck; if any of the factors was "off" the performance would be too.

 

The purpose of the French way was to ensure those circumstances applied every day, on nearly every train. 

 

John

Don't forget the need for a good run, little point putting the effort in, if for all the trouble, you get caught up by 'control'. Perhaps something slow being put in front of you, because you were already running late!

[slilley]

No Standard Fives had a double chimney. Ivatt did equip some of his Black Fives but it may have been just the Caprotti ones. The Stephenson valve gear Black Five had a double chimney in BR days.

Some of the conventional ones had double chimneys as well. Also a small number of Jubilees had them including late on the now preserved Bahamas.

[The Johnster]

The Britannias were not particularly good riding engines, especially for a Pacific. There was a heavy vibration came up through the floor emanating from the trailing truck, which was very tiring. The surge from the two-cylinder layout also lent a certain roughness.

 

The 9Fs on the other hand rode like a coach. I spoke to many men who were not keen on the 9Fs; they were too big for most of the work, for one thing, and they always preferred an 8F. But all admitted that they were a very comfortable engine as far as ride quality was concerned.

 

Canton drivers complained about draughts in the cab as well, coming up through the floor as there was no conventional  fall plate between the tender and loco.  This was rectified on later locos with the high sided tenders; I assume the same applied to 9Fs, but the lower speed of their freight work may have made the issue less apparent; I do not recall anyone complaining about draughts on WR 9Fs.  The Brits looked modern and sophisticated, but the men regarded them as rough and ready compared to Castles; Canton had been after Kings for it's heaviest jobs for years and eventually got them at the end of the shed's steam life, for a brief period.  

 

A powerful 2 cylinder loco will always have a noticeable surge; it prevented the Hawksworth Counties being used on loose coupled trains, and was very apparent with 56xx accelerating hard away from platforms (these could do 0-50mph in 5 coach lengths with 5 on).  This is uncomfortable in the train, punishing to frames, flanges, and track, and in general A Bad Thing.

[Corbs]

Thanks all for the replies and discussion. With the Hawksworth Counties, what effect did the double chimney conversion have? Was it for power alone?

[Dunsignalling]

Canton drivers complained about draughts in the cab as well, coming up through the floor as there was no conventional  fall plate between the tender and loco.  This was rectified on later locos with the high sided tenders; I assume the same applied to 9Fs, but the lower speed of their freight work may have made the issue less apparent; I do not recall anyone complaining about draughts on WR 9Fs.  The Brits looked modern and sophisticated, but the men regarded them as rough and ready compared to Castles; Canton had been after Kings for it's heaviest jobs for years and eventually got them at the end of the shed's steam life, for a brief period.  

 

A powerful 2 cylinder loco will always have a noticeable surge; it prevented the Hawksworth Counties being used on loose coupled trains, and was very apparent with 56xx accelerating hard away from platforms (these could do 0-50mph in 5 coach lengths with 5 on).  This is uncomfortable in the train, punishing to frames, flanges, and track, and in general A Bad Thing.

The "no-fall-plate" tender design had already been abandoned for new-build by the time the 9Fs emerged AIUI - the earliest ones had the BR1G pattern, as did the last.

 

The GWR 2-cylinder surge was very noticeable, even though the loco was not being worked hard, on a trip up the West Somerset Railway behind a 42xx 2-8-0T, anyone prone to travel sickness would not have enjoyed travelling in the front half of the train.

 

John

Edited October 7, 2018 by Dunsignalling

[The Johnster]

Thanks all for the replies and discussion. With the Hawksworth Counties, what effect did the double chimney conversion have? Was it for power alone?

 

I believe in the case of the 10xx Counties it was to improve steaming; nobody complained that the locos weren't powerful enough.  They were originally conceived as a fast mixed traffic design, indeed could not have been built under wartime regulations otherwise, but were a bit rough on freight work due to the 2 cylinder surge effect, breaking couplings and damaging goods in transit.  

 

Their forte turned out to be heavy passenger and parcels trains on routes with gradients, notably in Cornwall and on the North to West line.  But Hawksworth reverted to Castles for express work and modified the Hall for mixed traffic.  BR rated the Counties as 6MT, which equates to a V2 and is only beaten in mixed traffic terms by the Britannias.

[Corbs]

Thank you Johnster. Could I ask a stupid question? I don't really understand what is meant by 'steaming' in this context, do you mean the ability to make steam quickly so there is more available when there is a demand?

[Corbs]

Follow-up question for you engineering types - so if I have understood this correctly, there would be no point in installing a Kylchap/Double Chimney combination on a Beyer Garratt design, because the exhaust has to take such a long route from the cylinders to the chimney anyway, that a large single chimney would suffice?

[The Johnster]

Thank you Johnster. Could I ask a stupid question? I don't really understand what is meant by 'steaming' in this context, do you mean the ability to make steam quickly so there is more available when there is a demand?

 

Yes (sorry for delay, haven't checked this thread for a bit), steaming in this sense is the ability of the loco's boiler to raise steam at a faster rate than it is being consumed at the cylinders, which of course depends on the work being done.  It is part of a chain of events, though, and if the exhaust arrangements do not allow for the steam being used to be cleared from the exhaust side of the piston at least as quickly as it is being drawn in on the 'working' side (and in the case of a loco travelling at speed and working hard this can be a very large amount of steam indeed), the knock on effect is to retard the piston's movement and prevent steam being inducted on the working side at the rate required.  The bit between the cylinders and the chimney is described as the locomotive's draughting, and in some circumstances a double chimney can improve it.

[brack]

Follow-up question for you engineering types - so if I have understood this correctly, there would be no point in installing a Kylchap/Double Chimney combination on a Beyer Garratt design, because the exhaust has to take such a long route from the cylinders to the chimney anyway, that a large single chimney would suffice?

The big Algerian double Pacific garratts had a transverse double chimney (ie side by side) due to the short smokebox.

The East African Railways fitted giesl ejectors to a lot of their garratts, finding they could handle a couple of extra coaches compared to their brethren.

 

 

 

There are two things happening in the exhaust - steam from cylinders goes out through the chimney, but needs to also draw hot gases through the tubes from the fire.

 

Anyone thinking the longer exhaust circuit on a garratt might mean they don't have as defined a blast is recommended to look up garratts at fassifern bank on YouTube. You can clearly see the exhaust beats

Edited November 23, 2018 by brack

[Corbs]

Ah, thanks!

 

What an epic sight and sound!

 

Brack - I have a question in that case. My Garratt is a 4 cylinder loco for banking - short but intense workings followed by coasting back downhill. Would free steaming (and a big enough draw on the fire) be an advantage in this instance?

[brack]

Ah, thanks!

 

What an epic sight and sound!

https://www.youtube.com/watch?v=-1EWpCQP7eE

 

Brack - I have a question in that case. My Garratt is a 4 cylinder loco for banking - short but intense workings followed by coasting back downhill. Would free steaming (and a big enough draw on the fire) be an advantage in this instance?

Free steaming is always an advantage. But when is your garratt design from? If it's 20s/30s I wouldn't expect a double chimney. Those garratts I'd mentioned were hauling passengers at decent speeds for long distances - the EAR garratts were main line power and the Algerian ones topped 82mph on test and were meant for hauling 600 ton passenger trains at up to 75mph around 300m curves and up 1 in 38 (not all at once though!) Hence you can see their requirement for being free steaming. Due to boiler proportions most garratts were very good steamers. I wouldn't have thought a double chimney necessary for a banking loco primarily operating at low speeds.

 

Interestingly enough whilst beyer peacock incorporated most features of late steam development in their postwar garratt designs most were turned out with (admittedly rather fat) single chimneys. I suspect double chimneys weren't that much of an advantage otherwise BP would've shoved them on. The EAR and Rhodesian giesl conversions were later (60s). In Rhodesia they settled on a large multiple jet blastpipe and single chimney. The Alfred county NGG16As had a lempor fitted.

 

Essentially I'd stick with the single chimney. If the running gear is coming from old Robinson O4s then there's going to be more bottlenecks in the steam circuit there than in the smokebox.

Edited November 23, 2018 by brack

[The Johnster]

Free steaming is A Good Thing, and will improve any steam locomotive's performance in any situation. at the same time reducing the fireman's work load, and the coal and water consumption.  The boiler's capacity to raise steam is predictable as a function of grate or burner area, the heating surface available, the superheating, and the pressure.  It can be accurately worked out by men and women with rational minds and white coats, as can the tractive effort and cylinder performance.

 

When you get to the exhaust side of the piston, however, all bets are off.  Gone are the white coats, clipboards and pencils, and rational deductions, and the work is done in darkened gothic crypts by people in hooded cloaks by the light of black candles to the accompaniment of sinister chanting and the background eldritch screaming of the sacrificial victims.  It is the classic black and occult art, and the men responsible for it's successes, like Chapelon, Porta, Geisl, and Ell, are not to be trifled with, as the Dark Lord Who Must Remain Nameless Lest He Be Summoned protects them.  

 

This may be an exaggeration, but only a slight one...