Edward Thompson: Wartime C.M.E. Discussion

Do your sources say why the SER dropped the arrangement?

 

Hi Beckford,

Maunsell put a stop to Gresley pinching Holcroft from the SECR, and then allowed Holcroft free reign to do what he wanted on the 3 cylinder locos of the SECR. This was continued when the SR was formed. Maunsell, having 'proved his point' so to speak vis a vis Gresley, and bearing in mind his 3 cylinder conjugated gear locos were all long travel and performed far better than the A1s as originally built with short travel valves, then reverted to a policy of standardisation, and the conjugated gear locos were converted easily to 3 sets of valve gear.

Maunsell remained on good terms with Gresley as exemplified by the trails on the LNER after the Severnoaks accident.

Holcroft never stated his conjugated gear was better than 3 sets of gear. It was an option that was 'interesting' and a challenge to an expert at valve gear design (there are lots of subtleties in the conjugated gear that only modern computer simulation has found - see Don Ashton's work on this subject). He always acknowledged it had some advantages and some disadvantages. This is perhaps where Gresley was not so pragmatic.

Holcroft didnt mind at all his conjugated gear locos being converted to 3 sets of valve gear. He had enough footplate knowledge and shed experience to realise the shortcomings in practice. He went on to design for Maunsell quite novel Walschaerts gear for the 3 cylinder Z class, with 3 sets of valve gear, and with the combination lever movement being provided by an eccentric on the driving axle. He also was responsible for the novel Lord Nelson crank settings.

So we go from 1909 with a young Holcroft producing (perhaps as an academic exercise) a conjugated gear that Churchward insited was patented, and might have taken up (Churchward was very interested in it especially after Holcroft produced a working model) to Holcroft agreeing with Maunsell that really it wasnt worth the ticket in the 1920s in continuing.

Now compare this with Gresley and how this reflects on Thompson! I dont think you could describe Gresley as a pragmatist with conjugated gear. Rather than dwell on Thompson, lets look at how Peppercorn dealt with his locos. He didnt butcher any of Gresley's locos but built new with 3 sets of valve gear.

Cheers,
Julian

 

Just to be clear; use of high strength alloys doesn't affect stiffness. All steels are roughly as stiff as each other (i.e. Young's modulus is about the same). So to reduce whip, the combination lever needs to have its moment of inertia changed to increase its stiffness, not the alloy.

 

A second minor aside. The B17 and D49 had the conjugation behind the cylinders. Of course, the disadvantage is the reduced access to the valve gear.

 

Thank you for the link, most interesting. I do note Holcrofts praise for the LNER stud of locos which used Gresley's conjugated gear and his comment that it had been used by ALCO and throughout the world.

I agree that Holcroft's design prevents the problem of spindle expansion, but as I pointed out above that can be taken account of in the settings to produce the correct setting when the valves are hot - a condition that pertains during almost all of the loco's running time.

I also note Holcroft's comments about not losing the settings, however I understand that the settings on Gresley gear are achieved by flat shims in the ends of parallel sockets into which the valve spindle ends are held by taper cotters, and the rest of the gear uses fixed pivots. On that basis, as long as the shims are not lost or mixed up and the various link parts are kept in the correct order, disassembly and reassembly should not alter the valve settings at all. Actually setting the valves after replacement of various parts may well be a black art (Mr Riley had lots of fun with FS when the shims were lost) but for a p and v exam the setting should be maintainable. Sadly, I didn't get a chance to take Bittern's valve gear apart, but I did have a close look at it when it was in Ropley yard. Having been involved in taking valves out of various locos, I would point out that care must always be taken to drive the valve spindles into the valve crossheads the right amount to maintain the setting. I'd have been quite pleased to have the Gresley type of connection, since the ones I've done have been tapered seat type and thus have to be driven to marks, though I'm trying to remember if Tornado had shims - I think it did.
All that said, settings are a minor problem compared to getting the valves themselves out and back in.

With regard to whip, I agree the main beam has to be massive to prevent flexure, although achieving stiffness isn't just about weight, far more about depth of the beam (width, since it's lying flat) I understood this was a problem on the K3 class until the beam was widened and the pivot made much stiffer.

In the end I feel the Gresley gear to be a lot more elegant than the Holcroft variety and the benefits you and Holcroft point out are relatively minor in actual use - which in the end is the most important situation.

Agreed - he might also have developed the Gresley gear further to ease maintenance and applied the Swindon big end to the Pacifics a lot earlier.

I would imagine getting the setting right after overhaul must be a right pig. First getting the shims right for the outside valves and then the shims on each side to give just the right setting on the centre valve - including any offset for expansion. Even then there was probably room for improvement. Norman McKillop tells of badgering the foreman at Haymarket to alter a shim by "the thickness of this page" (a slight exaggeration) to get his favourite A3 Spearmint running perfectly.

I think it's more a case of applying the metal in the right place. As I said above, stiffness in a beam is more dependent on the beam section than its weight.

I think we may have to agree to differ on this. Thanks very much anyway.

Edit several hours later - I meant differ on the merits of the valve gear, not on the comprehensiveness of Julian's post.

 

I just want to give my apologies for not responding to everyone for their participation: may I say thank you to everyone for your thoughtful, insightful, and at all times respectful posting.

Oh Julian! I was so with you on everything up until the use of the word "butcher".

It's such a strange phenomenon. You've written a perfectly objective, thoughtful and insightful piece and then this word suddenly appears which changes the whole tone of the discussion from being an objective assessment to a personal belittlement of Thompson's engineering credibility.

In one word. The use of the word "rebuilt" would have been more objective. It is factual without personal viewpoint.

This sort of thing fascinates me so because it seems to be ingrained in railway enthusiasts of the LNER and they are always Gresley inclined.

Thompson rebuilt just 26 Gresley locomotives, the most notable being the 6 P2s, 1 A10, a D49, a K3, a K4, 10 B17s (the A2/1s do not count as they were built new, but based on the V2 design). By comparison, more Robinson and Raven machines are rebuilt under Thompson than Gresley locomotives - more O1s were built by nearly double the number of Gresley machines he had rebuilt.

Gresley by comparison as CME rebuilt more of Ivatt's, Raven's and Robinsons locomotives and nobody bats an eyelid.

Peppercorn continues with Thompson's wartime policies almost verbatim bar the last 15 A2s constructed to his design and the 49 new A1s. Classes like O4/8 and O1 are continued to be built and the L1 class was built as requested. The K1 had minimal changes to the front end layout and came out almost identical to Thompson's planned "Baby Bongos" which they are called regardless.

This is part of why I am so bullish on occasion I suspect. It never feels like quite the level playing field it should be when conducting an objective assessment of Thompson's work.

 

I'm minded of your recent description of Gresley's liking for three cylinders and his derived gear as a "character flaw" Now, he may have had character flaws, but I think you were unreasonable to describe his liking for a layout he'd had success with as a flaw. I didn't mention it at the time, trying not to start yet another debate on it, but since you pick up others I feel inclined to do the same to you. It seems you must find fault with Gresley to counter others' finding fault with Thompson. I realise you find the A1/1 to be the epitome of locomotive beauty - and fair enough, beauty is in the eye etc, but a majority of people who take an interest in LNER locos, and some who don't, find the Thompson rebuilt pacifics to be shadows of their former glory, in looks if not in performance. The term butchery has been used in print from almost as far back as the rebuilds themselves and its use above is hardly vitriolic. You really are way to sensitive about Thompson - perhaps it's no wonder your friend was so vehement - even if I think his basic premise was questionable.

 

I take your point about the use of the word "character flaw" but you've taken it out of its context completely. That was in reference to a perception of Gresley and that he would have dropped three cylinder conjugated gear in favour of three sets of walschaerts. So far as it goes he did nothing to suggest he would have done that and yet a number of authors and engineers suggest the Peppercorn A1 is evidence he would have done.

In addition I did not state the use of the word "butcher" as vitriolic and I certainly didn't infer it was used there in such a manner.

I feel you've actually missed what I'm saying. It's the use of the word and its context which is crucial.

 

It is indeed interesting to note the different "press" that Thompson gets compared with Peppercorn. However, Thompson's mission seems to have been to correct what he saw as flaws in Gresley's work; unfortunately in so doing he introduced some of his own. Had he not had that mission, he might have been more readily excused his own stumbles. Contemporary descriptions and assessments of his personality ("difficult" might be a tactful description) put the tin lid on his reputation for many. Peppercorn, by contrast, seems to have followed a more middle course and gets off lightly.

 

I quote you from the rebuild thread:-

When I said "flaw" - and forgive me for not putting it in context particularly well - it was in (and again in my opinion, but shared by others more reputable than me) Gresley's choice to keep the valve gear for small and medium locomotives, which as evidenced elsewhere before and after his passing was unnecessary. Two cylinders being more than adequate.

As I say, it isn't a character flaw to keep doing what has so far worked well. If the gear hadn't worked well you might accuse him of stubbornness, but that wasn't the case.

You complained that jmc1009 expressed a "personal viewpoint". So what? The whole point of your research over the last umpteen years has been a personal attempt to rehabilitate Thompson. Fair enough, that's up to you, and we understand that, but to censure someone for having a personal viewpoint which you disagree with, when this entire thread is based on your own personal viewpoint seem hypocritical.

 

Hi Simon,

I am sorry if my use of the 'butcher' word detracted from the information provided on the conjugated gear.

I wish you were writing a book on Churchward or Collett - we know just about everything about their engineering and design work, but very little about their private lives. A friend of mine is researching the life of WH (Willie) Pearce, the GWR valve gear supremo, and has uncovered much interesting stuff after a lapse of 110 odd years. Churchward and Collett both relied heavily on Willie Pearce. I have been helping and it is quite surprising what primary source material can now be found and accessed through the internet, that then provides leads to further primary source material.

My point is that so far as Thompson is concerned, there is no doubt a lot of primary source information still to be uncovered. O S Nock was well known for his lazy research, and C J Allen was a die hard Gresley fan.

I think that one of the most significant postings concerned access to a link to the original report commisioned by Thompson, under Stanier's signature condemning the Gresley conjugated gear. It was an appendix in the biography of Stanier. I dont want to go over old ground, but there is a lot of relevant original primary source material out there.

My personal view is that when you have a week off you need to go to Kew and review all the LNER board records, loco committee minutes etc for Thompson's period in office. You ought to research all the relevant loco record cards from the works. You really need to do the sort of in depth research of primary source material that say Michael Rutherford has done.

You also need to appreciate that appraising Thompson as a loco CME requires quite a high degree of technical knowledge to assess the locomotive designs.

An example might be how do you assess Stanier's report on the conjugated gear commisioned by Thompson, if you dont fully understand the intricacies of valve gear design and middle big end design? Lplus says there was nothing inherently wrong in the Gresley conjugated gear if well maintained. He quotes the post war performance of the premier ER expresses in the hands of Gresley locos with conjugated gear.

I do not disagree with his assessment.

But how does this subsequent knowledge compare with the Stanier report?

Did Thompson influence the report's findings? Was the writer of the report quite the best person to give an assessment of conjugated valve gears? (The obvious candidate for the report was Holcroft, as he was the leading UK expert in conjugated gears).

The report was commisioned by Thompson with a particular aim in mind I suggest. When O S Nock interviewed Thompson he wasnt shown the report, and what Thompson told him was misleading to say the least.

I dont quite get the 'wartime' conditions arguement. Lplus has stated many many posts ago the cost of ensuring the joints were properly lubricated in the conjugated gear in wartime were insignificant compared to the re-builds with 3-sets of valve gear by Thompson.

Thompson also completely failed to deal with the middle big end problem on the Gresley gear, despite this being covered in the Stanier report. The implementation of the solution had to await K J Cook's transfer to the ER later on after nationalisation.

The whipping of the long lever on the conjugated gear and consequent over-running of the middle cylinder valve were known well before WW2. Clayton and Holcroft both criticised the Gresley conjugated gear in 1925, and Mallard's record run was brought to an abrupt end, as was the incident when on 27th August 1936 with 'Silver Fox' Thompson suddenly appeared and ordered Driver Haygreen to 'top a hundred' (Nock 'Speed Records on Britain's Railways' p.151 quoting what Driver Haygreen told him at first hand).

Cheers,
Julian

 

I think there's potentially a very long distance between 'works acceptably when well maintained' and "nothing inherently wrong". To copy a para from a post of more than a year ago, in A E Durrants book he writes "It was an education to stand on Finsbury Park platform and watch a procession of northbound expresses... Gresley engines roared up under a vertical column of smoke, the hop, skip-and-a-jump exhaust betraying the fact that only two and a half cylinders were working... the Peppercorns purred up, faster, with all three cylinders fully operative..."

Holcroft almost certainly couldn't have brought the 'Swindon big end' to Doncaster BTW. The key developments were in lubrication and machining under Collett/Cook, long after Holcroft had left. That was the sort of unexciting yet vital development the oft maligned Collett was very good at.

 

Mallard was taken off the train with an overheated big end thought it didn't disintegrate. The big end of silver fox did lose its bearing brasses, though that has been blamed on the driver having to use far more cutoff than he would have otherwise done if he'd been prepared for a high speed attempt. Somewhere I recall reading Gresley gave Thompson a bollocking in public for that -which would have done little to endear him to his subordinate...

One wonders what would have happened if the revised big end had been in use at that time - even Cox didn't think the overrun of the middle valve had a significant effect on the middle bearing life. Didn't SNG do 112 post war and continued in service?

There's plenty of youtube clips around to allow comparison between well maintained A3 and A4 locos and the A1 working hard. I doubt you could tell the difference.
I wonder what year it was when Durrant was standing on Finsbury Park station.

Serves me right for being facetious I suppose. The major changes to the big end were to increase the size and fixing of the back strap on the big end to stop the brasses moving due to flexing and to change to a full whitemetal surface on the brasses with a long felt filled oilway across the top of the bearing. How much of that was GWR practice I don't know, and if it was I also don't know when it might have been developed.

 

Well, when i've seen that suggested it is always 'in the light of wartime experience'. Gresley simply didn't live long enough to tell what his response would have been. He was averse to changing his designs according to some people - and yet I have seen complaints from authors who were in the works in the Gresley era about the number of design changes that came through! As always, it is difficult to get the whole picture.

Certainly a designer who has engines on the road in hundreds is not going to want to change a major feature of design unless there is very good evidence for doing so - he would be a very bad manager if he did. But we have proven cases that when Gresley was given good evidence - as with the long/short travel - he did change his mind.

Gresley must have trusted Thompson as an engineer, he allowed him a much freer hand (it would appear) than anyone else, or indeed anyone in a similar position in the other big 4 (except, maybe, Holcroft). Witness the rebuilds he was allowed to undertake - it was not the rebuilding, but the release to the outside world of information about the rebuilding without going through 'channels' that Gresley objected to - as, again, any competent manager would.

Where the problem would appear to have originated is that Gresley did not understand Thompson's relative sensitivity as a person. Gresley clearly still had an element of the Victorian martinet in him and would speak his mind as and when he felt like it - Thompson would appear to have had more of the behaviour patterns (weaknesses and strengths) of a modern manager.

The Thompson Pacific's - well, for whatever reason, their designer allowed the design to be spoiled at least as much if not more by his own shibboleths as Gresley did with the original A1.

On the aesthetic point, in my personal opinion the A2/2's look pretty good, but I can't say that for the A1/1 . I don't honestly think the original P2's were especially handsome.

 

Wasn't the "Swindon Big End" French in origin?

 

F A S Brown records Gresley as being described as "a benevolent tyrant" and a senior official as saying" it was all right if Gresley liked you." Nuff said?

 

As I said, an element of the Victorian martinet. You could probably have said exactly the same of any Victorian CME. Except some of them were not benevolent.

But what about the point that, whether he liked or disliked Thompson, he allowed him to be involved in rebuilds in a way that , for example , Bulleid was never allowed to do? At lot that went on a Stratford after Thompson became works manager has a certain foreshadowing of things to come. The B12 and D16 rebuilds are credited to Gresley but was there not more than a hint of Thompson involvement? Especially in valve travel. If we accept the D20 rebuild is Thompson's work then surely that shows many of the same features?

 

Word of the week. Thank you.

 

It most certainly did and achieved three separate maxima of 100/100+ on that run.

 

I'm currently ill in bed with the flu so if any of the latter makes no sense, I reserve some right to blame the medication I am on!

Thompson and AE English were directly responsible for the D16/3 and B12/3. Thompson ordered locomotive 8579 to incorporate all of the features discussed between them as a demonstrator, effectively. There is a great description of the wooden mock up of the valve gear he and English had made, with Thompson turning the lever for English to work out valve events, in Grafton's book on Thompson, corroborated by other sources. Gresley's involvement as CME was to sign off the rebuilding of more of the class and also for the D16/3.

I completely agree on the D20. It seems to have been the forerunner of many of Thompson's standardisation ideals and also for the conversions carried out during and post war of other classes.

Yes that seems fair to me. I should quantify my stance better but it is difficult when you do not wish to over egg the conversation. The conjugated valve gear pre, during and post war received different levels of maintenance and modifications and as such the results of each should be considered in the full context of each time period.

There is a quotation in one of the books on Bulleid that suggests Gresley allowed Thompson a degree of free rein to "give him something to do" - I am paraphrasing there as it is a quotation at the back of my mind. I will try and dig out the source. If true, it shows a remarkable lack of respect to Thompson in public and shows a side of Gresley I wasn't expecting.

Again I feel this is a fair point, though Thompson does appear to have liked the ability to administrate to very exacting levels. However that has been described as one of his strengths by a number of sources, and there's no real shame in that if the main aim - getting the LNER in the best shape possible through the rest of the war - was achieved. And by hook or by crook, he did accomplish that on the whole.

That's interesting because in its original form I find the A1/1 to be the most handsome of the lot and the A2/2s though purposeful, don't quite have its elegance for me. I'm a founder member of no.2007 so my views on the P2s should be quite clear by comparison.

No need to apologise Julian - I wasn't picking on you per say but my point remains that it's the unquantified word that does the most damage. Lplus has above accused me of hypocrisy in putting forward my view on the valve gear - the difference being that I put forward my viewpoint and quantified it as subjective, whereas the use of "butcher" (seen elsewhere) is used in a more factual, unquantified sense. It is a subtle difference but it does affect how Thompson is perceived.

Which is fairer - the view which criticises Gresley but emphasises it is his personal view or the view which states Thompson butchered locomotives without quantifying why this is so?

That sounds most interesting and I look forward to buying a copy one day. I completely agree with you RE what primary source material can be found and accessed through the internet, though I have found that interviews with railwaymen and women still alive can also produce some surprising information. A single tip off led me to finding the despatches note on Thompson's award for war service.

OS Nock is a fascinating source of Thompson information, if only because the further you go away from when he was hired by Thompson to publicise the LNER through books and leaflets he wrote, to when he died his views become harder and harder, and more entrenched, to the extent that the fairly balanced work of the late 1940s bears little resemblance to the outright criticism of the 1960s and 70s. Whereas Cecil J. Allen, as you say, was a Gresley man, and his account in British Pacific Locomotives is one of the most astonishingly short and dismissive reads on Thompson's work available.

I was very lucky last year to get hold of an original copy of the report from an acquaintance who allowed me to copy it for my own purposes. As such the version I posted on this thread is not identical to that I have now read in Stanier's autobiography from Oakwood Press. If I had known about that it would have saved some time and thought but in the end it was beneficial as I was able to understand it all better.

I quite agree and have been doing this a little at a time for some time.

For me, I'm not looking to assess them from an engineer's point of view. I am not an engineer; though I did two years of an aeronautical degree I will not kid myself or anyone else into thinking that my mechanical understanding is anything the like of the some of the true engineers on here. However I do feel there is to some extent a great deal of unfair criticism and perhaps misunderstanding of Thompson's work from those who, like me, are not necessarily as mechanically inclined. I would rather point to the source material and ask "what do you think?" in my book than to point someone in a direction specifically.

That doesn't mean I don't have my own views and won't air them, but I will always try and quantify my views without wishing to influence.

I do not think anyone in this thread or in the wider world with disagree with that assessment. But a point keeps being missed. Thompson could not have foreseen the future when Gresley died and he was made CME shortly after. The post war performance of the valve gear is something Thompson could not have foreseen.

He was many things but like Gresley he was not a soothsayer.

ES Cox wrote the report (and Sir William Stanier signed off on that report) and from everything that he has written in his own books, Thompson did not influence his writing of the report at all. Cox claims that Thompson used the report "in a machiavellian campaign to rid the LNER of all that was Gresley" but I think it is fair to say from reading the report that he did not pull his punches in writing the report.

So there you have a perception that Thompson must have influenced the writer; there is evidence the writer was not influenced at all, and the writer himself then says his report was used to influence the LNER board to make changes.

It is a strange one how the perception of Thompson can be seen to be is wrong and yet is almost always made detrimental to him.

If you read ES Cox's report it makes three suggestions, one of which is to replace the conjugated valve gear with three sets of valve gear. So when you look at the report as a whole, and bear in mind the context of the time (wartime maintenance conditions on the LNER were at an all time low: not to mention the specialist lubricants available for certain classes, such as the Pacifics, were no longer available) it is clear Thompson may have been influenced by the report, rather than the other way around.

That last quote is intriguing and is one I will look up immediately. Thank you Julian.