UK 12 wheeled, 8coupled tank engines

[D605Eagle]

I'm trying to get a list together of all the UK 12 wheeled 8 coupled tank engines.

Sofar I have got

GCR 8H class 0-8-4T (I believe these were the largest most powerful tanks build for the UK)

GWR 72xx 2-8-2T

LSWR G16 4-8-0T

NER Class X 4-8-0T

LNWR Beames 0-8-4T

Are there any others? (standard gauge!)

Cheers

Jim

[34theletterbetweenB&D]

Interesting line up. Are you planning a grand, grand , grand all groups marshalling yard with examples of power from all over the UK?

 

Regarding power, the most powerful UK tank loco was undoubtedly the U1. The Midland Garratts should have been able to put out more power than the GCR tanks too (improbable though it sounds that any Derby design should ever excel in this field) and the GER Decapod was no slouch in the power output stakes, almost certainly able to outclass any of the eight coupled types you list, based on its demonstrated acceleration.

 

I think you have all the eight coupled twelve wheeled classes that made it into BR ownership. I hesitate to say there were no others, given the diversity of designs produced for the UK's railways. There was a nice looking proposal for a Gresley 2-8-2T with 4'8" drivers, looking very much like a V1 topsides.

[melmerby]

There was a nice looking proposal for a Gresley 2-8-2T with 4'8" drivers, looking very much like a V1 topsides.

On those lines there was an interesting proposal from the GWR of a 2-10-2T with 4' 7½" drivers and a T.E. of no less than 41,465lb, alternately with 4'6" wheels the T.E. would be 42,620lb!

With the 2-8-2Ts known propensity to straighten curves what would the 23' 0" driving wheelbase 2-10-2T done?

 

Keith

[D605Eagle]

Interesting line up. Are you planning a grand, grand , grand all groups marshalling yard with examples of power from all over the UK?

I hadn't thought about it, but my that would be some model railway! I just have a fasination in large tank enignes. A thread about 14 wheelers coming soon

 

Regarding power, the most powerful UK tank loco was undoubtedly the U1. The Midland Garratts should have been able to put out more power than the GCR tanks too (improbable though it sounds that any Derby design should ever excel in this field) and the GER Decapod was no slouch in the power output stakes, almost certainly able to outclass any of the eight coupled types you list, based on its demonstrated acceleration.

 

I think you have all the eight coupled twelve wheeled classes that made it into BR ownership. I hesitate to say there were no others, given the diversity of designs produced for the UK's railways. There was a nice looking proposal for a Gresley 2-8-2T with 4'8" drivers, looking very much like a V1 topsides.

Oh yes, I'd totally forgotten about the Decapod, I'll try and find what its TE was. The Wath dasies just pipped the other 12 wheelers TE, length and weight wise in standard form, but the Gresley built ones with boosters were massively powerfull, with a TE of nearly 47000 lbs.

I never considered the garretts as tanks, wouldn't they be classed as articulated locomotives?

Those proposed Gresley 2-8-2T would have been very handsome beasts. Some tallented guy on the LNER forum scratch built one IIRC.

The GWR 72xxs were in my humble opinion one of the most handsome looking freight tanks in the UK, and thats coming from an GCR/LNER man!

Jim

[Gordon A]

Garratts can be classified as tank engines because they dont pull a seperate wagon (tender) with coal and water.

Remove the rear chassis from a Garratt????????

 

Gordon A

Bristol

[John_Hughes]

On those lines there was an interesting proposal from the GWR of a 2-10-2T with 4' 7½" drivers and a T.E. of no less than 41,465lb, alternately with 4'6" wheels the T.E. would be 42,620lb!

With the 2-8-2Ts known propensity to straighten curves what would the 23' 0" driving wheelbase 2-10-2T done?

 

Keith

'Blind' (flangeless) central drivers would have helped, as well as the numerous well-tested dodges for making the coupled wheelbase more flexible, such as articulating the coupling rods horizontally as well as vertically.

 

Anyone so talented care to come up with a concept picture?

[melmerby]

'Blind' (flangeless) central drivers would have helped, as well as the numerous well-tested dodges for making the coupled wheelbase more flexible, such as articulating the coupling rods horizontally as well as vertically.

 

Anyone so talented care to come up with a concept picture?

 

What was the "rigid" wheelbase on a 9F? I wonder if they are similar?

There's the outline drawing in RCTS and other tomes with the specification re: boiler etc. So a possible "cut & shut" someone?

 

Keith

[pointstaken]

Possibly not quite what you're looking for, but didn't the Londonderry & Lough Swilly have a pair of 4-8-4 tanks ?

 

Dennis

[EddieB]

On those lines there was an interesting proposal from the GWR of a 2-10-2T with 4' 7½" drivers and a T.E. of no less than 41,465lb, alternately with 4'6" wheels the T.E. would be 42,620lb!

With the 2-8-2Ts known propensity to straighten curves what would the 23' 0" driving wheelbase 2-10-2T done?

 

Keith

 

Or, perhaps the ultimate "concept" is "Dusty" Durrant's design for a 2-14-4T, illustrated in his book "Swindon Apprentice". With a calculated TE of 74,125lb, the author envisaged it would replace two 9Fs on the Ebbw Vale iron trains. It was arranged with a 30' coupled wheelbase and the same 4' 7½" drivers (centre pair flangeless, next wheelsets thin flanged and 1½" play on outermost driving wheels).

[34theletterbetweenB&D]

...Oh yes, I'd totally forgotten about the Decapod, I'll try and find what its TE was. The Wath dasies just pipped the other 12 wheelers TE, length and weight wise in standard form, but the Gresley built ones with boosters were massively powerfull, with a TE of nearly 47000 lbs...

Never confuse the starting tractive effort estimate with 'power'. Power output in steam locos requires consideration of factors such as grate and superheater area; in addition to boiler pressure, cylinder volume and wheel diameter, that are used to generate the starting tractive effort estimate. These small wheeled eight coupled types were probably good for around 1,000 hp sustained output. Express passenger types with much larger firegrates and superheaters and TE estimates in the same 30 - 40,000lb range were capable of more like 2,000hp.

 

The GER Decapod had 43,000lb TE, and 42 sq ft of grate, no superheater. Probably good for circa 1,700hp in bursts.

[JOHNMCDRAGON]

The GSWR had some Baltic tanks, 4-6-4 wheel arrangement, I know there was Decapod, but I think this was only example of this wheel arrangement in everyday use in the early part of century, they were used for heavy, fast Clyde coast commuter services.

[Oldddudders]

If we're talking Baltic tanks, these were pretty successful. http://en.wikipedia.org/wiki/LB%26SCR_L_class. The arrival of the juice rail in Brighton in 1933 put them out of their prime role, and Maunsell rebuilt them to tender locos for the ex-LSWR routes. Why they were then called N15X is not clear - but it certainly gave them an image they couldn't quite live up to.

[D605Eagle]

The GSWR had some Baltic tanks, 4-6-4 wheel arrangement, I know there was Decapod, but I think this was only example of this wheel arrangement in everyday use in the early part of century, they were used for heavy, fast Clyde coast commuter services.

There were no less than 5 different standard guage baltic tanks that ran in the UK mainland. I was going to do a thread about them later on, and they are 14 wheelers BTW!

[Budgie]

'Blind' (flangeless) central drivers would have helped, as well as the numerous well-tested dodges for making the coupled wheelbase more flexible, such as articulating the coupling rods horizontally as well as vertically.

 

Anyone so talented care to come up with a concept picture?

 

There is this one (not mine, incidentally): http://www.flickr.co...in/photostream/

 

Or, perhaps the ultimate "concept" is "Dusty" Durrant's design for a 2-14-4T, illustrated in his book "Swindon Apprentice". With a calculated TE of 74,125lb, the author envisaged it would replace two 9Fs on the Ebbw Vale iron trains. It was arranged with a 30' coupled wheelbase and the same 4' 7½" drivers (centre pair flangeless, next wheelsets thin flanged and 1½" play on outermost driving wheels).

 

Why make it a rigid wheelbase loco? Surely it would be better to make it a Mallet articulated 2-6-8-4T or something like that?

[t-b-g]

Glad to see somebody questioning the use of tractive effort as a measure of how powerful a locomotive was. I have quoted this before but when the GWR announced that the King was the most powerful express passenger loco in the UK because it had the highest tractive effort, somebody answered with something along these lines........

 

"If you remove the coupling rods from a King, the theoretical tractive effort would remain the same. If you took the boiler off and replaced it with a Sentinel vertcal boiler, it probably wouldn't move itself but you would have increased the tractive effort because of the higher boiler pressure."

[D605Eagle]

Its all very well getting all high and mighty about TE excetera, but when thats the only available information at hand you have to use what you can. Be my guest and spend several hundred quid on books to find out measurements of DBHP etc. just for one thread. Peronally I'm really not that bothered about it. Several posters on this forum seem to take great pleasure in attempting to belittle people at any oppotunity.

[John_Hughes]

There is this one (not mine, incidentally): http://www.flickr.co...in/photostream/

 

 

(snipped)

 

 

Brilliant! And what fun for the fireman!

[Oldddudders]

Its all very well getting all high and mighty about TE excetera, but when thats the only available information at hand you have to use what you can. Be my guest and spend several hundred quid on books to find out measurements of DBHP etc. just for one thread. Peronally I'm really not that bothered about it. Several posters on this forum seem to take great pleasure in attempting to belittle people at any oppotunity.

Don't take it personally! We all quote figures and measures which we may not fully understand - while others are qualified in that area of expertise, and will occasionally bristle when we have indeed misunderstood and misconstrued the data. It happens.

 

My very thin knowledge of the history of the steam locomotive tells me that things like tractive effort appear to tell us much more than they actually do - and that designs that should have been successful sometimes turned out on rails to be complete dogs.

[62613]

Glad to see somebody questioning the use of tractive effort as a measure of how powerful a locomotive was. I have quoted this before but when the GWR announced that the King was the most powerful express passenger loco in the UK because it had the highest tractive effort, somebody answered with something along these lines........

 

"If you remove the coupling rods from a King, the theoretical tractive effort would remain the same. If you took the boiler off and replaced it with a Sentinel vertcal boiler, it probably wouldn't move itself but you would have increased the tractive effort because of the higher boiler pressure."

 

That spunds like the sort of thing Dr. Tuplin might have said!

[bbishop]

That spunds like the sort of thing Dr. Tuplin might have said!

 

And that reads like something Dr Spooner may have written.

 

Bill

[LMS2968]

For the record, ACTUAL Tractive Effort is the force that the loco exerts on the track to move itself and its train in a given direction. With a steam loco, it starts at the maximum at zero mph and falls exponentially as speed rises, the rate of fall depending on several factors, driving wheel diameter not the least but valve events also come into it. Adhesion also plays a part. NOMINAL Tractive Effort, as quoted in the ABCs, is a purly theoretical value with little relevance to actual conditions or ability to grip the rails.

 

Power is the loco's ability to keep a train moving at a speed, and is largely a function of the boiler's ability to generate steam in sufficient quantities over time, while tractive effort derives from an instantaneos boiler pressure, allied to cylinder dimensions and wheel diameter.

 

It does get more complicated than this, but I'm trying to avoid getting bogged down in the technology!

[t-b-g]

Its all very well getting all high and mighty about TE excetera, but when thats the only available information at hand you have to use what you can. Be my guest and spend several hundred quid on books to find out measurements of DBHP etc. just for one thread. Peronally I'm really not that bothered about it. Several posters on this forum seem to take great pleasure in attempting to belittle people at any oppotunity.

 

I don't really see how passing on a slightly humerous anecdote to illustrate why tractive effort does not equal power represents being "high and mighty" or "taking great pleasure in attempting to belittle people at any opportunity".

 

That spunds like the sort of thing Dr. Tuplin might have said!

 

 

I can't remember who wrote it but I read it in a letter in an old Railway Modeller from the 1960s. However, as quoting such pearls of wisdom caused the post above to be written, I now wish I had kept it to myself so that I didn't cause anybody any offence!

[asmay2002]

Its all very well getting all high and mighty about TE excetera, but when thats the only available information at hand you have to use what you can. Be my guest and spend several hundred quid on books to find out measurements of DBHP etc. just for one thread. Peronally I'm really not that bothered about it. Several posters on this forum seem to take great pleasure in attempting to belittle people at any oppotunity.

It's fashionable to rubbish people with actual knowledge. Please don't do it. You don't need to spend several hundred quid to know that lbs is a measure of weight or force and power is measured in horsepower or watts - having a pulse whilst at school should have been sufficient. "Using the only information at hand" is like saying Chelsea beat Liverpool 2-0 when asked what the score in the Man Utd vs Arsenal game was.

[Budgie]

Brilliant! And what fun for the fireman!

 

One would hope they would install a mechanical stoker, or build the loco to bun oil.

[Alan76]

Not 8-coupled, but it would have been 12-wheeled: the GC came up with a proposal for a 0-10-2 banking tank for the Worsborough Bank. It came to nothing, but the 'Wath Daisy' tanks were tried as bankers from Wath Yard to Dunford Bridge. Nice idea but it didn't work because the locos didn't have the water capacity.

 

Alan