Imaginary Locomotives

[John Besley]

10 hours ago, ScottishRailFanatic said:

“Sir, I think Mr Bulleid has gone mad.”

”You say that as if he hadn’t lost his marbles beforehand. The bleeding thing doesn’t even have front buffers.”

Pure Hornby Clockwork.... wheres the key?

[PenrithBeacon]

5 hours ago, The Johnster said:

True, but a King could not be built to conform to the loading gauge height had Castle wheels been used; the smaller drivers did increase the T.E. as well of course, which the publicity guys were appreciative of.

The demand for 40k TE came from the board. 

Do you have a source for the loading gauge  statement, I'd like to know more. Stanier managed to get the Duchess boiler into the LMS composite loading gauge with 6'-9" drivers. Seems a little suspect to me.

[rodent279]

Might there be other factors that would influence height/size of boiler? The GWR 4 cyl family was quite formulaic, with things like divided drive, length of con rods, position of cyl c/l relative to axles etc. Might those things have influenced, even dictated, the positioning of the boiler within the frames, and hence the size?

[JimC]

1 hour ago, rodent279 said:

Might there be other factors that would influence height/size of boiler? The GWR 4 cyl family was quite formulaic, with things like divided drive, length of con rods, position of cyl c/l relative to axles etc. Might those things have influenced, even dictated, the positioning of the boiler within the frames, and hence the size?

This is what I don't understand about the proposition.  The King boiler used the same flanging blocks as the Great Bear and the Std 7 (47xx) boilers, being intermediate in length between the two and having the same diameters. The Bear had pretty much a modified Star chassis and cylinders, and the Std 7 boiler on Star proposal that was abandoned due to weight problems was obviously also on a Star chassis, so there seems no obvious reason why the boiler couldn't have fitted over 6'8.5 wheels. There may of course have been more subtle reasons, which is why I'm so keen to hear if there's a good source for it. Its not in Holcroft or Cook to my knowledge, or even AFAICS in Nock.

[ScottishRailFanatic]

A short-range yard inspection vehicle, powered by batteries. Effectively a shunter’s truck with motors and a control panel.

[rodent279]

7 hours ago, JimC said:

This is what I don't understand about the proposition.  The King boiler used the same flanging blocks as the Great Bear and the Std 7 (47xx) boilers, being intermediate in length between the two and having the same diameters. The Bear had pretty much a modified Star chassis and cylinders, and the Std 7 boiler on Star proposal that was abandoned due to weight problems was obviously also on a Star chassis, so there seems no obvious reason why the boiler couldn't have fitted over 6'8.5 wheels. There may of course have been more subtle reasons, which is why I'm so keen to hear if there's a good source for it. Its not in Holcroft or Cook to my knowledge, or even AFAICS in Nock.

Just so we all understand, what is a flange block?

If I understand correctly, it is the piece or pieces of metal that the sheet metal forming the boiler& the firebox are pressed against in order to form the complex curves and bends where the two meet?

I'd imagine they are large, hard pieces of metal, unique to a particular boiler/firebox diameter, expensive to make.

If so, then one of several possible reasons for the King boiler being the size it is, could be that those flange blocks were available, weren't going to get used for anything else, and avoided the expense of making new ones.

The relative positioning of the boiler/firebox within the chassis might dictate how high it needs to be in order to clear the wheels, and in turn, it's maximum size. So a larger boiler might be able to fit within the loading gauge, if it was positioned sightly differently within the chassis.

Edited July 31, 2021 by rodent279

[ScottishRailFanatic]

What if the National Coal Board took its operations up a notch?

[Gibbo675]

1 hour ago, rodent279 said:

Just so we all understand, what is a flange block?

If I understand correctly, it is the piece or pieces of metal that the sheet metal forming the boiler& the firebox are pressed against in order to form the complex curves and bends where the two meet?

I'd imagine they are large, hard pieces of metal, unique to a particular boiler/firebox diameter, expensive to make.

If so, then one of several possible reasons for the King boiler being the size it is, could be that those flange blocks were available, weren't going to get used for anything else, and avoided the expense of making new ones.

The relative positioning of the boiler/firebox within the chassis might dictate how high it needs to be in order to clear the wheels, and in turn, it's maximum size. So a larger boiler might be able to fit within the loading gauge, if it was positioned sightly differently within the chassis.

Hi Rodent,

 

Here is the film No. 6207, A Study in Steel, it shews the building of an LMS Princess Royal at Crewe works. The boiler flanging blocks are to be seen at 11:00, although the whole film is worth a watch.

 

 

 

Gibbo.

[billbedford]

15 hours ago, Compound2632 said:

 

That doesn't quite square (so to speak) with Hunt et al., op. cit., so I'm curious as to the evidence for this. The boiler design was very much in the Derby tradition, being based on the boiler for the Lickey banker. Obviously the Derby LDO would have been able to supply NBL with the relevant drawings.

 

...but, but, but the Lord Nelson fire box was a completely different beast from anything Derby built, having sloping crown and back plates.  One of the class, Lord Hood, was fitted with 6'3" driving wheels, but "no advantage could be detected"

 

 

 

15 hours ago, Compound2632 said:

Anyway, here's an NBL-built Belpaire-boilered outside-cylindered 4-6-0 of 1905.

 

Precursor of the GER Clauds?

[Compound2632]

6 minutes ago, billbedford said:

...but, but, but the Lord Nelson fire box was a completely different beast from anything Derby built, having sloping crown and back plates.  

 

Hunt et al. comment on that:

 

"It has been suggested that since the G10¼S was the first 'Derby' boiler to feature a sloping throatplate that this must have been copied from the 'Nelson' but, as already mentioned, Derby LDO had included such a firebox in its 1924 proposal for a 3-cylinder compound 4-6-0 and Herbert Chalmers was known to favour the type."

[rockershovel]

1 hour ago, Gibbo675 said:

Hi Rodent,

 

Here is the film No. 6207, A Study in Steel, it shews the building of an LMS Princess Royal at Crewe works. The boiler flanging blocks are to be seen at 11:00, although the whole film is worth a watch.

 

 

 

Gibbo.

 

I note that at the time, "engine" and "locomotive" were used synonymously.

 

love the business of balancing the lifting beam by more or less men sitting on it!

[Compound2632]

I've found the discussion of the calculations of TE at 25 mph (goods) and 50 mph (passenger) used to determine the LMS power classifications. It starts a bit before this post and carries on some way after but gets there in the end:

 

 

It's evident from Mr Gass' L&Y curve that the King's long piston stroke and smaller diameter wheels would have an unfavourable effect on mean effective pressure, only saved by the increase in boiler pressure:

 

Piston speed at 50 mph = (stroke / 26") x (81" / driving wheel diameter) x 899 ft/min

 

Castle: stroke = 26", diameter = 80.5", piston speed = 905 ft/min, MEP = 29% of boiler pressure = 65 psi.

King: stroke = 28", diameter = 78", piston speed = 1,005 ft/min, MEP = 26% of boiler pressure = 65 psi.

[Michael Edge]

1 hour ago, Compound2632 said:

 

Hunt et al. comment on that:

 

"It has been suggested that since the G10¼S was the first 'Derby' boiler to feature a sloping throatplate that this must have been copied from the 'Nelson' but, as already mentioned, Derby LDO had included such a firebox in its 1924 proposal for a 3-cylinder compound 4-6-0 and Herbert Chalmers was known to favour the type."

It's hard to find anything of the 4 cylinder Lord Nelson in the 3 cylinder Scot, the firebox is the only story I've heard but one other possibility is the inside Walschaerts valve gear. I haven't got a GA of the Nelson to compare them though.

[MikeOxon]

On he subject of flanging blocks, I believe Hawksworth designed the boiler of his 'County' class to use the flanging blocks that Swindon already had for wartime building of Stanier 2-8-0s.

[rodent279]

4 hours ago, Gibbo675 said:

Hi Rodent,

 

Here is the film No. 6207, A Study in Steel, it shews the building of an LMS Princess Royal at Crewe works. The boiler flanging blocks are to be seen at 11:00, although the whole film is worth a watch.

 

 

 

Gibbo.

Thanks. So flanging blocks are basically as I said, big lumps of metal that form a die that shapes the complex curves of the boiler & firebox. So they would dictate the size of boiler & firebox, at least in terms of height, width & diameter. I could imagine that they are costly & time consuming to produce, & if you've got some spare lying around not doing much, those holding the purse strings might encourage you to use them.

[PenrithBeacon]

I have often thought that when people talk about standard boilers they should really be talking about 'standard flanging blocks ' because of similar circumstances to the way the King boiler was designed. 

There is really no justification for the idea that the King was compromised by the need to adopt 6'-6" drivers. If anything,  the King was compromised by it not being a Pacific. The Lizzie was the engine the King should have been.

[tythatguy1312]

7 minutes ago, PenrithBeacon said:

I have often thought that when people talk about standard boilers they should really be talking about 'standard flanging blocks ' because of similar circumstances to the way the King boiler was designed. 

There is really no justification for the idea that the King was compromised by the need to adopt 6'-6" drivers. If anything,  the King was compromised by it not being a Pacific. The Lizzie was the engine the King should have been.

that's always been infuriating to me, as I live right at the start of the places a King feared to tread, with the Royal Albert Bridge being within visual range of my house. A 4-6-0 has great climbing power, yes, but a Pacific of the same weight can use that power in many more places. I always do wonder why the GWR didn't use the bear as a starting point for the Kings, as there was a lot of room to improve.

[JimC]

12 minutes ago, PenrithBeacon said:

I have often thought that when people talk about standard boilers they should really be talking about 'standard flanging blocks '

There's a good deal of truth in that. GWR standard boilers came in distinct families, based on, amongst other things, the flanging blocks.  Both barrel and firebox could be longer or shorter. These families can be identified.
Std 6, 7, 8 used the same (the Bear's set)
Std 1 and 4
Std 2, 3, 10 .

Metro, Std 11, Std 21
Class P (Dean Goods), Class N, Std 9
Classes U, R, V, S, SS, Std 16
Most out of place were the two boilers designed against really big weight issues, the Castle, which was originally a Std 7 with a smaller diameter barrel, and the Manor. 
It must have pleased Hawksworth that the government had bought him a set of blocks intermediate between the Castle and Std 1 sets, which gave him more options.

[JimC]

21 minutes ago, tythatguy1312 said:

 I always do wonder why the GWR didn't use the bear as a starting point for the Kings, as there was a lot of room to improve.

You could argue that they did. There was a great deal of common DNA. But a Pacific costs a lot more money without adding that much extra capability, so why would you build one if you didn't have to. And a substantial part of the theoretical extra carrying capacity of the trailing wheel is taken up with carrying the extra weight of wheel and truck. Its worth noting that inter alia A4, Merchant Navy and Princess Coronation were all too heavy for GWR red routes, and indeed the published axle weights for the Princess Coronation exceed those for the King.  Even the original Gresley A1 was half a ton heavier on each driving wheel than the Castle, which was on the red route limit.

[Compound2632]

4 hours ago, JimC said:

There's a good deal of truth in that. GWR standard boilers came in distinct families, based on, amongst other things, the flanging blocks.  Both barrel and firebox could be longer or shorter.

 

Same thing goes for LMS boilers - certainly the "G" family of Midland-derived parallel Belpaire boilers. 

[PenrithBeacon]

4 hours ago, tythatguy1312 said:

that's always been infuriating to me, as I live right at the start of the places a King feared to tread, with the Royal Albert Bridge being within visual range of my house. A 4-6-0 has great climbing power, yes, but a Pacific of the same weight can use that power in many more places. I always do wonder why the GWR didn't use the bear as a starting point for the Kings, as there was a lot of room to improve.

I think so was so much wrong with The Great Bear that it would have been better to start with a clean sheet of paper. 

One of the things that was wrong at Swindon is the way it dropped good ideas if they didn't work first time. Stanier must have found the attitude on the LMS so different. 

[rodent279]

Swindon seemed to stick so rigidly to Churchward's ideas that it failed to see where deviating slightly might benefit things. I think the Princess was the greatest enlargement of the Churchward 4 cyl 4-6-0 concept possible within the UK loading gauge, but just putting a bigger boiler and firebox on what amounted to a King chassis with an extra trailing axle didn't seem to fully answer the WCML problem.

[Northmoor]

1 hour ago, rodent279 said:

Swindon seemed to stick so rigidly to Churchward's ideas that it failed to see where deviating slightly might benefit things. I think the Princess was the greatest enlargement of the Churchward 4 cyl 4-6-0 concept possible within the UK loading gauge, but just putting a bigger boiler and firebox on what amounted to a King chassis with an extra trailing axle didn't seem to fully answer the WCML problem.

Arguably, the "WCML Problem" was only solved by the E-word: Electrification.

[PenrithBeacon]

2 hours ago, rodent279 said:

 ...

just putting a bigger boiler and firebox on what amounted to a King chassis with an extra trailing axle didn't seem to fully answer the WCML problem.

All very mystical, but what was the WCML problem?

[Compound2632]

Just now, PenrithBeacon said:

All very mystical, but what was the WCML problem?

 

Corridor carriages and speed. If folk had been content to hold on while their train jogged along at a 40 mph average speed between stations and to stop for half an hour for dinner at Preston, Webb's little engines would still have been doing the job.