Smoke Deflectors

[alexl92]

It was pointed out to me yesterday that express engines built by the LMS, LNER and SR generally always needed smoke deflectors of some type or other, but the GWR never found need for them on their 4-6-0s.

Does anyone know why this is the case? What was different in the GW designs?

 

[Llanigraham]

Because the GWR knew how to design their engines properly!




I'll get my hat.

 

[70014IronDuke]

It was pointed out to me yesterday that express engines built by the LMS, LNER and SR generally always needed smoke deflectors of some type or other, but the GWR never found need for them on their 4-6-0s.

Does anyone know why this is the case? What was different in the GW designs?

I believe it is in part due to the higher loading gauge allowed on the GWR. It allowed them to have slightly higher chimneys, which helped lift the smoke and steam exhaust.

Then we had the double chimney modifications on some locomotive classes.

When the LMS and LNER introduced double chimneys, the problem got more difficult, as the twin exhaust rings produced an even softer exhaust. So, for example, the rebuilt Royal Scots needed something doing, while most Jubilees and Black 5s never had deflectors - being single chimneys, they didn't need them. Same for the A3s until they got double chimneys. See recent thread with contributions by MarkyT, son of Top Shed's Townend

http://www.railforums.co.uk/showthread.php?t=123334&page=3&highlight=townend

 

[TheEdge]

Because the GWR knew how to design their engines properly!




I'll get my hat.

Why do you need a hat? Its the correct answer.

 

[D365]

Why do you need a hat?

He needs the hat to deflect the steam off his face!

 

[edwin_m]

He needs the hat to deflect the steam off his face!

No, it's a stovepipe hat.

 

[HSTEd]

Because the GWR always did things differently because it could.

 

[30907]

url]http://www.railforums.co.uk/showthread.php?t=123334&page=3&highlight=townend[/url]

Thanks for the fascinating link, from a forum I don't regularly read.

 

[colchesterken]

I think the full size ones look better. I do not like the German style fitted to Scotsman
Spam can is best of all, except the streamlined Duchess, and of course the Brits & the Duke...

 

[sprinterguy]

I think the full size ones look better. I do not like the German style fitted to Scotsman

I thought that the German style smoke deflectors suited the clean lines of the A3s very well. However full size smoke deflectors far better suited the greater bulk and longer smokeboxes of the LNER A2/3 and Peppercorn A1s, and personally I think that the Princess Coronations look somehow denuded without smoke deflectors

 

[coppercapped]

I believe it is in part due to the higher loading gauge allowed on the GWR. It allowed them to have slightly higher chimneys, which helped lift the smoke and steam exhaust.

Then we had the double chimney modifications on some locomotive classes.

When the LMS and LNER introduced double chimneys, the problem got more difficult, as the twin exhaust rings produced an even softer exhaust. So, for example, the rebuilt Royal Scots needed something doing, while most Jubilees and Black 5s never had deflectors - being single chimneys, they didn't need them. Same for the A3s until they got double chimneys. See recent thread with contributions by MarkyT, son of Top Shed's Townend

http://www.railforums.co.uk/showthread.php?t=123334&page=3&highlight=townend

Another small point. The taper on the boilers of GWR locomotives was quite pronounced which meant that, size for size, the smokebox diameter tended to be smaller than that used by other companies. This in turn meant that the top of the chimney stood higher than for comparable designs with the effect you mentioned.
Whether the smaller smoke box had other disadvantages I don't know - it was probably more difficult to fit self-cleaning kit inside them and the GWR used quite low degrees of superheat so the superheater headers wouldn't have been so big.
Even with 4-row superheaters and double chimneys, the GWR locos didn't need deflectors, see https://www.youtube.com/watch?v=A4r5SklgMCU

 

[theageofthetra]

Smoke deflectors seemed to be used far less in the US-and they had some enormous smoke boxes with very short chimneys. I accept many were oil fired, but many weren't and the NW had plenty of Mallets (or simple versions) which must produce a less forceful exhaust?

 

[deltic08]

Another small point. The taper on the boilers of GWR locomotives was quite pronounced which meant that, size for size, the smokebox diameter tended to be smaller than that used by other companies. This in turn meant that the top of the chimney stood higher than for comparable designs with the effect you mentioned.
Whether the smaller smoke box had other disadvantages I don't know - it was probably more difficult to fit self-cleaning kit inside them and the GWR used quite low degrees of superheat so the superheater headers wouldn't have been so big.
Even with 4-row superheaters and double chimneys, the GWR locos didn't need deflectors, see https://www.youtube.com/watch?v=A4r5SklgMCU

No, not a small point, the main point. All GWR 4-6-0s were taper boiler with smaller diameter smoke boxes. All locos with smoke deflectors had parallel boilers except the rebuilt Royal Scots, Patriots and two Jubilees 'Comet' and 'Phoenix' fitted with 2A boilers. The Duchesses were built and ran initially without but were soon fitted.

Stanier's Princess Royal Pacifics were a copy of Swindons finest so were taper boilers.

I was brought up on Castles and Kings but enjoyed the Duchesses, Scots and Patriots when visiting grandparents in West Cumberland. They looked more powerful with smoke deflectors but of course a King was more powerful than a Duchess both in tractive effort and hauling ability.

The driver who went out to America with 6000 (but really 6018 in disguise) used to come into my fathers garage for servicing and repairs. I remember him relating the tale many times that the Yanks laughed discreetly at such a small loco compared to theirs until one day he wiped the smiles off their faces by winding up 6000 with quite a heavy load behind, even without Welsh coal in the firebox, and was asked to slow down as the Yanks weren't used to these speeds with that weight behind.

 

[DarloRich]

Because the GWR knew how to design their engines properly!




I'll get my hat.

the GWR engines didn't need smoke deflectors as they didn't go fast enough

 

[MarkyT]

. . . the Yanks laughed discreetly at such a small loco compared to theirs until one day he wiped the smiles off their faces by winding up 6000 with quite a heavy load behind, even without Welsh coal in the firebox, and was asked to slow down as the Yanks weren't used to these speeds with that weight behind.

The USA had few 'multi-cylinder' steam engines of simple unarticulated chassis design. A few 3-cylinder examples were tried but by far the majority were 2-cylinder, although there was room there for particularly large outside cylinders, bigger than even the GWR could accommodate on the former broad gauge network! It's understandable the power to size ratio must have seemed impressive. To get more powerful over there they just got bigger, much bigger in the latter days of later big boys etc. In Europe and especially the UK, designers didn't have that luxury.

 

[ilkestonian]

I'd have thought the key reason GWR didn't tend to need deflectors was simply that they designed their locos with a sharper exhaust than most of the other railways. You've only got to watch and listen to a GWR loco working to appreciate this, and a sharper exhaust is less likely to drift.

Maybe also a greater tendency to run with full regulator and short cut-off too?

 

[MarkyT]

. . . the GWR locos didn't need deflectors, see https://www.youtube.com/watch?v=A4r5SklgMCU

That's at what 70 or 75MPH? Take that to 90 or 95 and the exhaust will drift lower. Fantastic video BTW thanks!

. . . they designed their locos with a sharper exhaust than most of the other railways. You've only got to watch and listen to a GWR loco working to appreciate this.

Yes, GWR and LMS designs used rather smaller blastpipe orifices, even in the double chimney variants, compared to the double chimney A3s and other larger LNER designs. The double Kylchap modification aimed to reduce back pressure involved in ejecting the expanded steam from the cylinders and hence get more useful work out the power strokes, so used a larger blastpipe with lower flow resistance. On its own that would have reduced draft unacceptably, so the design used a series of nozzles and cowls inserted into the exhaust flow in the smokebox to increase the pull on the fire. This was most successful in freeing up the engine, increasing power available and boiler steaming rate whilst saving coal, but the larger orifice reduced the exhaust force undeniably, highlighting the need for smoke deflectors on the A3s when they were modified. In addition to their superior smoke lifting abilities, other advantages of the German style deflector were the simple two bracket fixing to the smokebox sides, requiring no modification or obstruction to the footplate below (so staff could continue to move around easily at the front of the locos), and their relatively small size representing as little obstacle as possible to crews' forward vision, improvement of which which was the whole purpose of the exercise to fit them after all!

 

[E&W Lucas]

I'd have thought the key reason GWR didn't tend to need deflectors was simply that they designed their locos with a sharper exhaust than most of the other railways. You've only got to watch and listen to a GWR loco working to appreciate this, and a sharper exhaust is less likely to drift.

Maybe also a greater tendency to run with full regulator and short cut-off too?

Oh dear, oh dear.

Get your head round what is actually inside the smoke box, don't just look at the bit you can see from the end of the platform.

Bedtime reading:
GWR jumper blastpipe
Difference between a double blastpipe and a kylchap system.

 

[deltic08]

the GWR engines didn't need smoke deflectors as they didn't go fast enough

Except diminutive 4-4-0 City of Truro, the first loco to reach 100mph, near Taunton on a Plymouth-Paddington mail train more than a Century ago.

The Cheltenham Flyer that held the world record for end to end average speed of 77mph between Swindon and Paddington. I would imagine speeds in the high 90s would be required to give an average this high.

The Bristolian in the late 1950s was fast non stop Bristol-Paddington with eight bogies Mon-Thurs and ten on Fridays when a King replaced a Castle. 90mph was held most of the way from Wootton Bassett to Acton.

Apart from Swindon-Paddington there weren't routes straight enough or flat enough for continuous high speed in steam days on the GWR. Cotswolds, Chilterns, South Devon Banks, Welsh Mountains. Where else on the national system is there a 1 in 42 gradient where 10 coach trains regularly ran, mostly unassisted, to or from London? That is why GWR locos were smaller wheeled 4-6-0s for power rather than speed and why hydraulic gearboxes were chosen instead of electric transmission in pioneer diesels. Horses for courses.

 

[DarloRich]

Except diminutive 4-4-0 City of Truro, the first loco to reach 100mph, near Taunton on a Plymouth-Paddington mail train more than a Century ago.

It is said. There is no documentary proof.

The Cheltenham Flyer that held the world record for end to end average speed of 77mph between Swindon and Paddington. I would imagine speeds in the high 90s would be required to give an average this high.

The Bristolian in the late 1950s was fast non stop Bristol-Paddington with eight bogies Mon-Thurs and ten on Fridays when a King replaced a Castle. 90mph was held most of the way from Wootton Bassett to Acton.

Indeed - but on a nice, flat, easy running line in good condition

Apart from Swindon-Paddington there weren't routes straight enough or flat enough for continuous high speed in steam days on the GWR. Cotswolds, Chilterns, South Devon Banks, Welsh Mountains. Where else on the national system is there a 1 in 42 gradient where 10 coach trains regularly ran, mostly unassisted, to or from London? That is why GWR locos were smaller wheeled 4-6-0s for power rather than speed and why hydraulic gearboxes were chosen instead of electric transmission in pioneer diesels. Horses for courses.

They weren't built in Darlington or Doncaster so they are no good

PS humour is lost on some people! Horses for courses is the best description

 

[edwin_m]

They weren't built in Darlington or Doncaster so they are no good

PS humour is lost on some people! Horses for courses is the best description

Especially if they happen to be named after racehorses?

 

[Spamcan81]

No, not a small point, the main point. All GWR 4-6-0s were taper boiler with smaller diameter smoke boxes. All locos with smoke deflectors had parallel boilers except the rebuilt Royal Scots, Patriots and two Jubilees 'Comet' and 'Phoenix' fitted with 2A boilers. The Duchesses were built and ran initially without but were soon fitted.

Stanier's Princess Royal Pacifics were a copy of Swindons finest so were taper boilers.

I was brought up on Castles and Kings but enjoyed the Duchesses, Scots and Patriots when visiting grandparents in West Cumberland. They looked more powerful with smoke deflectors but of course a King was more powerful than a Duchess both in tractive effort and hauling ability.

The driver who went out to America with 6000 (but really 6018 in disguise) used to come into my fathers garage for servicing and repairs. I remember him relating the tale many times that the Yanks laughed discreetly at such a small loco compared to theirs until one day he wiped the smiles off their faces by winding up 6000 with quite a heavy load behind, even without Welsh coal in the firebox, and was asked to slow down as the Yanks weren't used to these speeds with that weight behind.

LNER A1, A2 and A3 classes all had taper boilers as did the Maunsell 2-6-0 classes as well as the Britannias and the Clans. In fact most locos fitted with smoke deflectors had taper boilers.
As for the Kings being more powerful than the Dichesses - nonsense. Highest ever horsepower recorded by a UK steam loco was a Duchess. As for the KIng worrying the Americans, you do realise that they had locos capable of cursing along at 100 mph with a 1000 tons on the drawbar?

 

[ilkestonian]

Oh dear, oh dear.

Get your head round what is actually inside the smoke box, don't just look at the bit you can see from the end of the platform.

Bedtime reading:
GWR jumper blastpipe
Difference between a double blastpipe and a kylchap system.

Thank you for your helpful and informative post.

The question posed by the OP related to the absence of deflectors on GWR locos, so a detailed thesis on advances in internal streamlining by other companies didn't seem appropriate.

But a little addition illumination from you with regard to the GWR jumper or variable blast pipe design would have been appreciated and have added to the thread, rather than sarcastic assumptions which don't advance the discussion.

 

[Spamcan81]

I'd have thought the key reason GWR didn't tend to need deflectors was simply that they designed their locos with a sharper exhaust than most of the other railways. You've only got to watch and listen to a GWR loco working to appreciate this, and a sharper exhaust is less likely to drift.

Maybe also a greater tendency to run with full regulator and short cut-off too?

Most modern steam locos were designed to run with full regulator and short cut off so in that case the GWR express locos were no different. You are quite right about the sharpness of the blast though.
--- old post above --- --- new post below ---

Except diminutive 4-4-0 City of Truro, the first loco to reach 100mph, near Taunton on a Plymouth-Paddington mail train more than a Century ago.

Never authenticated and still a subject for debate over 100 years later.

The Cheltenham Flyer that held the world record for end to end average speed of 77mph between Swindon and Paddington. I would imagine speeds in the high 90s would be required to give an average this high.

Until the LNER Coronation streamliner took that record.

 

[sprinterguy]

As for the Kings being more powerful than the Duchesses - nonsense.

That part is, to my knowledge, actually true. Under British Railways, the "Kings" were recorded as having a maximum tractive effort of 40,300lbs, the "Duchesses" a maximum of 40,285lbs.

I'm aware of the Duchess record for sure, but has a "King" ever been meaningfully measured against it?

 

[ilkestonian]

That part is, to my knowledge, actually true. Under British Railways, the "Kings" were recorded as having a maximum tractive effort of 40,300lbs, the "Duchesses" a maximum of 40,285lbs.

I'm aware of the Duchess record for sure, but has a "King" ever been meaningfully measured against it?

Tractive effort is a theoretical measure which bears little relation to actual power, as measured on the road, with a dynamometer car, or at the erstwhile Rugby Loco Testing facility, so isn't tested. It is simply calculated from the quoted figures for wheel diameter, cylinder size and boiler pressure.

The GWR were not averse to using tractive effort in their publicity; claiming (IIRC) that the Kings were the most powerful locomotive when introduced simply because their TE was fractionally higher than the Southern's Nelsons, which had eclipsed the Castle's earlier title, much to the chagrin of the GWR's publicity department.

I think I've read somewhere that Collett was leaned on to tweak certain dimensions to produce "good" TE figures, compared to the original King design, and thereby regain the title of "Most Powerful Loco" from the Southern.

There was something of an arms race between the Big Four, or at least their publicity departments!

 

[sprinterguy]

Tractive effort is a theoretical measure which bears little relation to actual power, as measured on the road, with a dynamometer car, or at the erstwhile Rugby Loco Testing facility, so isn't tested. It is simply calculated from the quoted figures for wheel diameter, cylinder size and boiler pressure.

The GWR were not averse to using tractive effort in their publicity; claiming (IIRC) that the Kings were the most powerful locomotive when introduced simply because their TE was fractionally higher than the Southern's Nelsons, which had eclipsed the Castle's earlier title, much to the chagrin of the GWR's publicity department.

I think I've read somewhere that Collett was leaned on to tweak certain dimensions to produce "good" TE figures, compared to the original King design, and thereby regain the title of "Most Powerful Loco" from the Southern.

Ah, fair enough, thanks for the clarification.

 

[deltic08]

It is said. There is no documentary proof.



Indeed - but on a nice, flat, easy running line in good condition



They weren't built in Darlington or Doncaster so they are no good

PS humour is lost on some people! Horses for courses is the best description

Acknowledged as being so. Why was City of Truro preserved if it wasn't so?

I already said it was the only section of the GWR where high speed was possible.

If this comment is directed at me, although not sure what you mean, I am GWR through and through but still contributed the equivalent of 'a pint a week' (I am teetotal) towards Tornado built in Darlington.

Did you?
--- old post above --- --- new post below ---

Just passing on an interesting story as told to me by the actual driver so it is not lost forever. He was elderly and 30 years after the occasion but I have no reason to disbelieve him. I think his name was Mr Trigg if anybody wants to look it up.
--- old post above --- --- new post below ---

Check your facts before making a Dich of yourself.

 

[70014IronDuke]

.....

The Cheltenham Flyer that held the world record for end to end average speed of 77mph between Swindon and Paddington. I would imagine speeds in the high 90s would be required to give an average this high.
....
The Bristolian in the late 1950s was fast non stop Bristol-Paddington with eight bogies Mon-Thurs and ten on Fridays when a King replaced a Castle. 90mph was held most of the way from Wootton Bassett to Acton.

Going rather OT

I thought it was 7 carriages and 8 on a Friday, but maybe you are correct.

Can you show a run where it was 90 mph for long distances? I remember studying some of the (supposedly) best runs in Trains Illustrated (or MR) and noting that the speeds were within a narrow band of 80-85 mph, but not above 85 and never touching 90 mph.

I think these runs were when the train was diagrammed for the first D8xx and one was not available - 1959? time.

Please note, I am not trying to decry this achievement, I think it was astonishing driving skills - just seeking to determine that 90 mph was not the norm (but not saying that this was never reached), only that rather 80-85 mph was maintained consistently for around 90 miles of travel, bar permanent speed restrictions at the odd spot, such as Reading.

 

[deltic08]

Going rather OT

I thought it was 7 carriages and 8 on a Friday, but maybe you are correct.

Can you show a run where it was 90 mph for long distances? I remember studying some of the (supposedly) best runs in Trains Illustrated (or MR) and noting that the speeds were within a narrow band of 80-85 mph, but not above 85 and never touching 90 mph.

I think these runs were when the train was diagrammed for the first D8xx and one was not available - 1959? time.

Please note, I am not trying to decry this achievement, I think it was astonishing driving skills - just seeking to determine that 90 mph was not the norm (but not saying that this was never reached), only that rather 80-85 mph was maintained consistently for around 90 miles of travel, bar permanent speed restrictions at the odd spot, such as Reading.

If you say so.

A film was made with 7018 hauling. The guard is shown checking the stock and tells us the weight for that day. Perhaps you can find it.

My return train home after a days spotting left Bristol just after the Bristolian. Always a clean Castle and chocolate and cream coaches. Glorious site

When the Warships replaced steam, speeds definitely were above 90mph and occasionally above 100mph until limited to 90mph max.