Edward Thompson: Wartime C.M.E. Discussion

The original 4470 was dismantled and the replacement 4470 was mostly a brand new loco, with new frames. Its previous frames dating from 1933, were re-used on Harvester (Locomotives of the LNER Part 2A p.174).

 

So if you subscribe to the "the frames are the identity" school of thought Thompson is innocent?

I fear though all that tale does is demonstrate that we shouldn't regard the loco's identity as being resident in any particular component...

 

I'm not sure anyone believes that, do they - except the specialist press, who endlessly bang on about it despite all evidence to the contrary!

Indeed.

If I've understood that right, are you saying that "Great Northern" - built in 1922, received new frames in 1933? Eleven years' life is pretty short, and certainly puts into context the preservation-era issues with Flying Scotsman's frames. How many miles had she done by 1933?

Not being an LNER aficionado - were the A4 frames significantly different / redesigned relative to those on A1/3s?

Tom

 

I am not a particular LNER aficionado either but the RCTS Locomotives of the LNER is a tour de force, far better than the their GWR series, and very readable. The history of the A1/A3 frame problem is covered on p32-33 of Part 2A and troubles with cracking started very early on. Some locos got entirely new frames but later the preferred solution seems to have been to replace the front three quarters, forward of the trailing coupled axle, with Doncaster keeping spare sets of same, so locos could be turned round quickly at overhaul. Thus the new Grand Parade was ready apart from wheels before the damaged one arrived at Doncaster. Re A4 frames, there is a brief section (p101-102) which starts "The arrangement of the frames conformed basically to the latest A3 practice with additional improvements." I note in particular that the horn stays were bolted to both the horn blocks and the frames (instead of just to the horn blocks).

 

I don't suppose there exists a list of times to prepare and dispose of Thompson engines vs predecessors and perhaps in comparison to other railway designs? Didn't several of his designs feature self cleaning smokeboxes and rocking grates?

 

Indeed, like the analogy of human beings to a wave whereby the identity is discrete from the collection of atoms that happen to make up the physical form at any particular moment. Perhaps locomotives are more anthropomorphic than we think?

 

Depends on what you've been drinking.

 

LPlus, you seem to be suggesting Thompson KNEW his design was worse than the A3, so deliberately tested it against an A1 (or A10 as T would presumably have said) to get approval to build more locos he knew were bad?!?!?!
I am completely mystified unless you think ET was pathologically insane.
He must have thought his new design was good. He presumably didn't test it against the non-standard Kylchap A4, because there wet only half a dozen of them and hence not at all representative of LNER traction.
His new design was to be the standard, replacing (on the front line) A3, A1 and augmenting A4.
The Peppercorn A1, which retained much of the Thompson ethos in the sense of the same brief and lots of the same incremental improvements, of course developed off a side branch a bit further back via the P2 rebuilds, the A2/3 and the Peppercorn A2. They were generally found to be better than an A3 but not the equal of a Kylchap A4 on the top link. So were they duds, by your reckoning...?

 

I'm totally bemused by that part of your post.

I sincerely thank you for reminding me of where to find a quotation ( when I am away from my source material which contains, at last count in the bibliography, around 105 publications including railway books, engineering journals, contemporary magazine and newspaper reports, biographies and similar) and your first instinct when met with a genuine thank you is to rubbish the individual giving it.

Rather unwarranted I'm afraid.

 

But Great Northern wasn't tested against an A10 (which is what Gresley A1 became during the war). She was tested against two Gresley A4s. Golden Plover and Sir Ralph Wedgwood, both single chimney A4s.

She had a double kylchap and the same type of boiler as the A4s. There were only 4 A4s with double chimneys and there were 30 A4s with single chimneys. They formed the majority of the top link of 6ft 8in Pacifics on the LNER (the single chimney A10s and A3s effectively the second string by comparison - I am in no way saying this to deride them, far from it they were very able machines but the A4s were the LNER's top link).

Thompson was designing a locomotive class to succeed the Gresley A4, post war. Hence why the frame, stay and horn block arrangement, and the boiler of the A4 was kept, and effectively a Thompson front end put on. He kept everything that he liked about Gresley's A4 designed and incorporated all that he felt was important (with one exception: equal connecting rods. Perhaps by this point of his engineering career he had acknowledged that equal length connecting rods on a 3 cylinder locomotive were not absolutely necessary?)

You don't compare the new design with the oldest classes, you compare it with the current top link. Modifications were made to 4470 off the back of these tests.

There's the word: prototype. Great Northern was a prototype.

The point I am trying to make is that the comparison was meant to be, as near as possible anyway, what the standard in the fleet was like compared to the future. 4470 proved to be as economical as a single chimney A4, maybe a little better in places. No shame in that for the older design nor was the one off prototype perfect.

We forget that Great Northern was originally to have been streamlined like the A4s. This might have incorporated the wedge shaped cab in addition. Thompson however reverted to the flat front cab on his A2/3 and A1/1 designs - the wedge shape of the P2 and V2 designs being kept for those rebuilds/new builds.

 

Ok, the figures I quoted were from Gavin Morrison's book and were supposed to be mileage as A2/2's. That's what you get for not cross-referencing sources . I've got the Green guide as well!

 

Someone replied to this earlier - just a couple of additional points:

First, one presumes the cracking was not regarded as dangerous.

The replacement system went on right up to the last general repairs in 60/61.

Gresley - or his drawing office - redesigned the A4 frames and they did not have the same problem - at least, there is no record of similar frame changes being necessary.

The idea that a loco's identity is tied up with the frames is an absolute myth, certainly as far as the GNR/LNER is concerned. Frame changing or replacement seems to have been something that Doncaster accepted as a matter of course. Many of the Stirling engines got through two or three sets of frames. Probably why they didn't turn a hair at the Deltic engines requiring a similar replacement and off-line repair process.

The private owners of FS have apparently not been aware of the frame problems which is a little surprising. Had they been then a spare set of frames might have been a sensible purchase to go with the spare boiler.

 

The problem with the Thompson Pacifics - and it is really quite unfair to keep concentrating on the Pacifics, unless we are going to go on about Gresley's J39's or Stanier's 2-6-2T's - was not that they were uneconomical, inefficient or whatever, it was that they needed a great deal more maintenance than the other classes they were 'competing' with. And since the prime reason for the design changes was to improve maintenance compared to the Gresley conjugated Pacifics it's reasonable to say they failed in Thompson's prime intention. I don't know how quickly this became apparent, not all the comments are dated , but it really seems to have been quite soon after they entered service, and clearly the designers of the Peppercorn variants knew exactly the cause of the problem - the odd frame layout at the front and the other design features that followed from that.

About , what, 800 engines of Thompson's designs were built / rebuilt, and about 600 of those were either perfectly good engines, or no worse than the engines they were rebuilt from., say 75%. Comparing to other CME's I'd say that's about par for the course if not better than average. Not everyone can be a Churchward. And even he produced the odd dud.

 

That's an even-handed assessment, but not the one handed down through history - which comes back to the question, why does Thompson alone attract a deal of opprobrium not reserved for other CMEs?

Tom

 

Firstly, in post 1189 I wrote A1 instead of A4 whilst quoting P Townend - my mistake, though I did use the correct number 31 which was an A4. The next sentence also refers to A4. In my post 1195 I made no mention of the A1/A10.

the reference to an A10 was this:-
"an other wise excellent engine, generally more powerful and easier to work than in its original form, slightly if anything more economical than the majority of the A4's of the time had been spoiled by the positioning of the outside cylinders and the problems arising therefrom." so, a loco with an A4 boiler and kylchap exhaust was better than a 180 lb A10 with single blastpipe

The quotation was from P Townend, who was making a general observation about the A1 in relation to the A10 (the original form). The remainder was a clarification of what I understand P Townend was saying. The A1 was not specifically tested against an A10. Sorry to those who thought I was saying it was

Indeed, but he used the A4 boiler and kylchap exhaust on his new loco with his revised frames valve gear and cylinder placing. Assuming the boiler and kylchap were equal, why didn't he test the loco against a kylchap A4 which had the same boiler and exhaust, thus highlighting the improvements he expected due to his new layout?
A simple question - if he thought is was better, why not test it against the best of the existing?

As to whether it was deliberate, isn't it just possible that it was?

Not sure I follow you there - The Peppercorn A1 had a different boiler with a bigger firebox but with Kylchap exhaust and in theory and I believe in practice was a better heavy hauler than the A3/A4 I seem to recall that once the train loads were reduced, the A4s were considered better for the fastest expresses, perhaps on ease of running and maybe fuel consumption with the lighter loads? I've never considered the Peppercorn A1 to be a dud.

 

I wrote the entire post because you were exaggerating P Townend's approval of 4470. I had to get the book out to confirm my impression and then write yet another detailed post on this extremely long thread as to why I thought you were at fault in this particular case. I then find you hadn't checked it when quoting. I'm pleased you now have found the page in question, and I hope you accept what I wrote as being a true record of P Townend's views.

 

Oh, come on - really? You may not agree, but having read this thread you can see why enthusiasts of Gresley and the Gresley locos, particularly the A3/A4 might be so animated against Thompson, given what is known to date. Mr Martin is hoping to change that, but until he publishes his book we won't know if the railway enthusiast world will agree with him. I doubt the proponents of other companies care, so it'll be the LNER enthusiasts he has to convince.

 

Not really, no. I can see *that* they are so animated, but I still don't understand *why* they are so hostile...

 

Clearly many of them are, and always have been, very animated against Thompson, but this thread includes many examples of things that Thompson got right and things that other CMEs got wrong.

Yes, it will be good for the book to be finished, giving as complete and balanced account as Mr Martin can provide. Even then, of course, it will be human nature for people to take heed of the bits that support their existing beliefs and ignore the bits that challenge those beliefs.

 

Maybe it's an LNER thing....