Edward Thompson: Wartime C.M.E. Discussion

In the case of the Lord Nelsons, I think that at least in part they were a "crew sensitive" design. In the right hands with experienced crew they gave excellent results, but because there weren't many of the class built, many crews didn't gain sufficient familiarity with their quirks; in particular, firing to a very long grate that had a distinct change of slope mid way along its length. An inexperienced crew could let holes build up where the grate changed slope, leading to a sudden loss of pressure; or else end up constructing a "wall" midway across the box with the fire too thin at the front, leading to the same result. By contrast, the King Arthurs were easier to fire and, with so many in traffic (along with S15s and H15s with essentially identical boilers), crews became familiar with how to get the best results from them.

The Schools was an interesting design. I've always felt that Maunsell's best designs were when he had a series of constraints to work round, and in the Schools, he had probably the tightest set of constraints of all, and ended up designing his masterpiece. By contrast, with the LN he had more or less a clean slate, and ended up designing arguably his most flawed loco.

Tom

 

While not being a Southern aficionado at all (apart from appreciation of the survival of all those wonderful pre-grouping classes) I have always rated Maunsell much higher than most. One of his great strengths was not being precious about his own designs, being happy to use elements of other people's designs, and working with a team who he allowed to influence him.
It was a great shame for the GSWR that he didn't stay longer at Inchicore!

On a different note, many posts back we discussed multiple cylinder locos from overseas. I later recalled that the Nigerian Railways had some 3-cylinder 4-8-2 locos with Gresley gear, on the 3'6'' gauge. They were built by VF in 1930 and lasted until the 1960s.

 

As already noted, Gresley gear was popular pre-WWII on locos with three cylinders. Going back to my earlier example of the Thai Baldwin Pacifics, where a different arrangement was preferred on later batches, I have found this drawing in the Locomotive for 1928 of the valve gear of a 3'6" gauge Manila RR Baldwin Pacific, the same as that used on the later Thai Baldwins, showing two sets of outside valve gear on the RHS (LHS on the Thai locos), with two return cranks, two expansion links etc. The same volume of the Locomotive has an article on a three-cylinder pacific for the Buenos Aires and Pacific Rly (AW, three sets of valve gear), a pacific for the Federated Malay States Rly (NBL, Gresley), Victorian Rlys S Class pacific (VR Newport, Gresley) and South African 18 Class 2-10-2 (Henschel, Gresley).

 

You may have forgotten the NSW D-57 Class 4-8-2, introduced in 1929. Built by Clyde Engineering with a massive set of Gresley Valve Gear for the centre cylinder.

 

Or the Union Pacific 4-12-2s, or the Japanese C53s, or the South Manchuria Railway Mika-ni etc, but it was not an attempt to catalogue all such locos, merely a note of others appearing in The Locomotive for 1928. The sway beam on the D57 is certainly massive, or agricultural, depending which adjective you prefer.

 

The Russians had some 3-cylinder locos with the third set of valvegear outside the frames and a rocking arm to drive the inside cylinder, a few of the UP 4-12-2's were altered the same way. I don't know if loading gauge would prevent that solution in the UK.

 

Here's a link to the post with the Stanier/Cox report.
http://www.national-preservation.co...lysis-2012-present.35938/page-33#post-1081993
Its worth re-reading again, because we seem to be losing sight of exactly what Stanier said.

Here's the "management summary"

To put it in even simpler words.
1 - the conjugated valve gear has inherent problems and *should not be repeated*.
2 - it *might* be worth considering replacing the conjugated gear on some classes.
3 - the fundamental problem with the big ends is *the big end design*, not the conjugated gear.

The other thing that seems to being frequently missed about the report is that it states that the problems with valve timing owing to wear are not confined to excessive work done by the middle cylinder at speed, but that the effects will be different in different circumstances.

 

Without wishing to divert from what is a genuinely fascinating diversion onto other designs, the above part of the report is one of my big bug bears about the reporting of Thompsons history.

Cox describes him as using the report in a Machiavellian campaign - but he didn't exactly mince his words, did he?

OS Nock dismisses it as Stanier (who signed off on the report) merely saying he wouldn't use it himself - which in light of what the report actually says is almost a complete fabrication.

This is part of why I question if Thompson has been given a fair deal in the reporting of his work, post the Cox report.

Look at those recommendations - Thompson carried out Coxs recommendations to the letter.

Not perpetuating the conjugated gear - check.

Rebuilding some classes with three independent sets of gear - check.

Try out different types of big end? There were a few minor trials including relining a few A4s in addition to that.

Overall it strikes me that a fair reporting of the whole thing is dependent on actually understanding what the report said, putting its writing into context of the time it was written, and then analysing what came next to understand why it happened as it did.

Which frankly isn't what has happened previously. No we get "Thompson wanted to rid the LNER of Gresley". Ho hum.

 

I almost completely agree with you, but the thing that most causes me to pause is Cook says. almost as an aside, in the epilogue of his book 'Swindon Steam', , "Perhaps I was able to heal a little of the discord brought in by Edward Thompson's tragic desire to obliterate Gresley."

So no matter that Thompson's decisions seem rational and engineering led with the benefit of hindsight, there was certainly a very different feeling on the ground at the time. I don't know how much Cook would have known Gresley and Thompson. He records meeting Bulleid and Weatherburn, the dynanometer car head, but doesn't mention the other two.

 

That's an interesting quote - I'll try and get a copy of the book to have a read. Thank you for the heads up on that.

 

Simon,

Your lack of context background knowledge astounds me! Cook's book although primarily GWR based deals also with his period on the ER. How could you not have read yet such an important work?

So far as the Cox/Stanier report in 1942 is concerned, Cox's statement that the Gresley gear is incapable of being made into a sound mechanical job is rubbish. Lplus asserted it was ok before WW2 and after, and I agree with his conclusion. Holcroft stated in papers I've previously quoted how the levers could be 'tweaked' to avoid overrunning of the middle cylinder if thought necessary. Flying Scotsman has been running around all day today performing faultlessly with the Gresley gear, and delighting many thousands in the process.

To get back to the Maunsell link, it is significant that all the Maunsell locos had all 3 cylinders 'in line', but with the middle cylinder inclined except on the Schools. This is apart from the Schools the same arrangement Gresley used. The major failing of Thompson was to have a middle conn rod with an 'ahead' cylinder driving the front driving axle, that weakened the frames and produced an ugly and poor engineering arrangement, and poor steam and exhaust pipe connections.

All the SR 3 cylinder locos had pretty much equal connecting rods. There was no need for Thompson to have the middle conn rod drive off the front driving axle.

Cheers,
Julian

 

Only in the very sketchiest way...

However that's merely an assertion, whereas the engineering logic in the paper seems unassailable. Its certainly true that the conjugated gear, serviced well, worked adequately, but that's not at all the same as saying it was a thoroughly sound design.

What, like those notoriously unreliable and unsuccessful GWR 4 cylinder locomotives?

 

Hi Julian,

I am learning all the time. Nobody starts out with a base knowledge of everything and I'm grateful to those people who've cited sources and pointed me in the directions of specific works. I am but human.

I've alerted a number of people to the existence of the Cox report and provided copies on request including a bibliography of the work I'm undertaking.

I'm not a GWR man so although I was vaguely aware of Cook, if you come at it from an LNER centric point of view his work and influence isn't immediately obvious in light of Gresley, Thompson and Peppercorn.

It's through this thread that I've learned a great deal and I am grateful for your thoughts on these matters.

On the subject of the report: you once again cite that pre and post war use of the conjugated valve gear makes Coxs report rubbish.

The point I've now made about a dozen times is that the Cox report is a snapshot in time of what was happening in 1942.

Of course it's not reflective of pre-war conditions: because it's reporting on the current situation.

It cannot possibly report on post war dealings because post war hadn't happened yet.

I'm not trying to justify away the failings of Thompsons work. I'm trying to put it into context and to ask if he is fairly reported on and treated in hindsight.

I've said a number of times that I agree there was nothing wrong with the valve gear if maintained well. I'm not arguing against that: that you seem to think I am perplexes me.

So let me be clear, for avoidance of doubt: my book and the aims of my book are not to denigrate Gresleys engineering work. It's to investigate Thompsons work and to see if it's been fairly reported in history.

The Cox report is part of that, and that you and Lplus repeatedly cite its use pre and post war as justification against Thompsons actions actually misses the point of what I'm trying to achieve here.

 

That is very clever Jimc, but I think actually we would ultimately agree.

A dodgy valve gear doesnt produce the UK and World speed record for steam.

With 4 cylinders on the GWR locos the Pearce valve gear worked perfectly, and the 2 middle cylinders provided a substantial frame stay. The rocker arm arrangement with cranked arms worked perfectly.

In comparison there is lot of evidence that the Thompson Pacifics shook themselves to pieces on the front section of the frames.

Incidentally I doubt anyone would claim that oiling up a GWR King was easy with that great big horizontal stretcher on top supporting the weighshaft intermediate and expansion links. And all those corks! An SR Schools must have been/is far simpler.

Cheers,
Julian

 

Why not? You may as well say a faulty big end doesn't produce the World record for steam, but clearly it did.

The A4s were a significant advance on what went before, but that doesn't mean they were perfect in every respect.

 

Hi Simon,

I hope we are getting down to the nitty gritty!

We seem to be making some progress in identifying the key engineering issues.

So far as WW2 is concerned can I please refer you again to what Bill Harvey said. He had a number of solutions including simply avoiding smokebox ash getting on the 2 in 1 lever and pins. So simple!

But what does Thompson do instead?

I suggest this is really the crux of the matter re Thompson against which all his other decisions get based and judged.

I should stress I have not the slightest interest in LNER locos, being a diehard GWR and Brighton fan. I have no bias one way or the other re LNER loco design and policy.

Cheers,
Julian

 

Have you forgot that Mallards middle big end overheated? Although not anywhere near as damaged as done sources exaggerate, this was a known problem.

So a world speed record made and the valve gear in question suffers.

So is that really evidence to help your view, Julian?

Where is this evidence Julian? Please cite it.

It was certainly true of the A2/2s - but then they shared that problem with the P2s as both classes had spliced frames at the front end. Thompson created the A2/2 by utilising this part of the P2 design.

The spliced section was between the first and second coupled wheels on the P2 - which on the A2/2 was between the cylinders and the front driving wheels. The A2/2 was effectively made by bolting on a new front end in place of the old one.

Hence, flexing of the frames at that point was possible and this was in practice a flaw across the same point. Throw in three separately fitted cylinders and the class certainly had the potential for shaking itself loose between the frames, between joints to the steam pipes, and between the cylinders and frames.

This was not the case on the A2/1 which didn't have spliced frames in the same place. The A2/1s did share the A2/2s problem of keeping the separate cylinders tight to the frames.

This was a trade off between the strength of the mono bloc against the easier maintenance of removing one cylinder instead of all three when renewal was necessary.

The A2/3 was a very similar engine to A2/2 - but the frame design was improved compared to the P2 derived A2/2.

The problems of the three separate cylinders was retained - again a trade off between maintenance and performance, one presumes.

However the biggest problem of the A2/2s wasn't the frames. It was the boilers.

Until the decision was taken to renew them with Peppercorn boilers, the six A2/2s spent considerable time waiting for their own boilers to be repaired - they had a pool of seven boilers (reduced to six when Wolf of Badenochs original boiler was scrapped).

I cite Peter Townends work - East Coast Pacifics at Work is very illuminating. There are other sources too but it is late and I am tired. I'd be happy to send you a copy of my bibliography once it's complete.

Part of my research has led me to read the engine cards available at York, NRM, and the details are vague in parts to say the least.

One thing is clear - none of the Thompson Pacifics nor Peppercorn machines suffered the frame fractures the A10s and A3s did. 3/4 length frame replacements from the 20s all the way through to BR days for these Pacifics.

The A4s didn't suffer this as their stay arrangement was beefed up and improved.

In preservation most recently Flying Scotsman has had the front 1/3 of its frames renewed. She's had a tough preservation life, of course, but the fact remains this was necessary and that's down to the design.

Strange though - nobody uses that to batter Gresleys reputation despite it being worse than the Pacifcs which followed.

 

Hi Simon,

I think you have quoted enough examples to prove my point! I could quote a few more sources but I would be repeating previous posts.

The LNER pacifics were well known for frame problems, as were the B1s. The thickness of the frame plates was always rather 'thin' and in the case of the B1s the thinnest of all.

On the otherhand many contemporary commentators in Inst LE debates commented on how the Bullied Pacifics had very sturdy well designed frames. This pattern formed the basis of the BR standard classes. Bulleid designed his in WW2, as did Thompson, but I think any reasoned assessment would say Bulleid did a much better job than Thompson!

Cheers,
Julian

 

I quote you:

"I feel that I have the ability to go and write a book that should give the facts, and if possible restrain myself enough to ask if others can read it, and do as I feel I have done - sought out both sides of the story and made my views based on that. If I fail in that task, I will have failed Edward Thompson more than if I had simply championed him. It should not be about that, it should be about letting others make an informed opinion on such matters. They haven't been able to before and now I hope, I can help there."

This is what you are supposedly trying to achieve here, to allow others to make an informed opinion. So will your book include the views of those you disagree with? Will it include the questions I asked about the report and the reservations I have about it? How it was obviously a report on the war situation, but criticizes the Gresley gear as if there had been no successful use prewar? Will it include the questions I have about why Cox was so vague about the report in his memoirs? Will it explain that Nock was vague about the report because he didn't see it? Will it explain the differences between the full report and the edited version in Stanier's biography. And I'm not just concerned with my own arguments. Having skimmed through the whole thread, I am amazed by the number of posts both for and against Thompson by so many people. So in short, will you fairly put both sides of the arguments you have heard on this thread in your book? You have every right to draw your own conclusions in your book, but unless you present both sides of the argument first, you will not be achieving what I have quoted you as wanting to achieve, you will simply be providing the sort of biased reporting you accuse all the other writers of.