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Edward Thompson: Wartime C.M.E. Discussion

Discussion in 'Steam Traction' started by S.A.C. Martin, May 2, 2012.

  1. S.A.C. Martin

    S.A.C. Martin Part of the furniture

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    Julian, I've never given you a vitriolic reply in this thread. A firm one, definitely, a hopeful one that the next response to me might be a bit more humble, but never vitriolic.

    Not just Spencer: it was made up of the statistics on availability, maintenance times, and physical examinations of the spare sets of conjugated valve gear and what was involved in overhauling/replacing a set.

    The timing is by no means coincidental. I would like to think I have been diplomatic in my wording previously.

    Point of information. Great Northern does not have, nor never had, equal length connecting rods and was the only Thompson Pacific designed this way. She also had the highest overall availability of the Thompson classes and finished with the highest mileage too. Is it about valve gears? Given the significantly improved availability of the A2/2s after rebuilding, one could be forgiven for thinking that Thompson and his design team had proved a point.

    So, not Thompson's successor...at all?

    Come now Julian - this is clearly a nonsense.

    Peppercorn was Thompson's successor. Cook was Peppercorn's successor.

    Thompson started a revamping of the major locomotive works policies and maintenance approaches - which Peppercorn continued. Cook then changed dramatically the way frames were set up at Doncaster. The improvement in availability in the 50s as a result of this was clear - and it affected the Gresley locomotives in particular, because they were all coming from a place of low availability whereas the Thompson and Peppercorn designed Pacifics already had high overall availability. Yes - even the A2/2s are not as bad as has been previously described when you look at their engine card records.

    Thompson was working in the middle of the second world war, with limited resources, manpower and intense pressure from the board, War Department, and more. Cook was working in an entirely different scenario. Might I suggest that this is a poor comparison? The hard work for Cook had already been done by the time he took up office at Doncaster. Both Thompson and Peppercorn had changed the emphasis on new builds and changed the requirements for overhauls (an example I gave earlier in this thread was the use of a boiler inspector to determine if a locomotive should be shopped on the basis of the boiler or if it could continue in traffic).

    Thompson was not interested in developing conjugated valve gear any further. He is more than justified in changing the policy as CME. That is the end of the matter.

    I have read Cook's autobiography and his time at Doncaster is a footnote in his overall history. Bizarre that you claim it completes a picture - it is a very short piece.

    The thing you do not seem able to grasp is that Thompson was not interested in developing or fixing conjugated valve gear. That's a perfectly reasonable line of development.

    Bulleid went to the Southern and promptly discarded almost every single thing he had seen at the LNER in the development of his own Pacifics. Thompson's team, by contrast, kept the Gresley round topped boiler, 6ft 2in wheels, tender, overall layout and the kylchap double chimney together with some modifications to improve the steam circuit.

    He discarded the conjugated valve gear and this one decision led directly to the Peppercorn A1s thereafter.

    Cox's report was based on internal statistics and evidence furnished by the LNER. Sir William Stanier had an overview and agreed on its wording. We have since been able to glean more information from the availability of LNER locomotives during the war and beyond. if Cox's report is somehow "biased and poor" then you need to explain specifically which part of the stats it refers to (corroborated by the data we have) is somehow biased.

    I feel I have said all I need to on this post, and if I may, I will not write further on Spencer in this thread. It is wearying to repeat the same points ad infinitum.

    Nail, head, hit.

    On these questions:
    • Thompson's choice to reduce to two cylinders for small and medium sized locomotives was in line with literally everyone else in the UK at that time. If this is "wrong" then the GWR, SR, and LMS combined are all "wrong", which seems unlikely. The rest of the world also did this.
    • Under Gresley and Thompson there were some modifications to the conjugated valve gear and different big end bearings used, in addition with lining the cylinders differently on a couple of A4s. All inconclusive and all abandoned. Thompson's policy change set things in motion for future builds and Peppercorn built on his decisions.
    • Peppercorn stuck with three sets, divided drive, and went for his connecting rod setup as it was likely seen as a "best of both worlds" approach - and there is no doubt, given the high availability of his roller bearing A1s, that he was abundantly right to do this.
    The immediate changes were to how locomotives were shopped and what criteria were applied to shop them. Newer locomotives - though they didn't call it this at the time - were shopped more regularly for less intensive maintenance (a "preventative maintenance" approach" which made availability much higher.

    Gresley locomotives were "run to failure" mostly due to the difficulties in dismantling and the nature of the conjugated valve gear being seen as one complete set - you don't swap over only one valve gear, you do the outside pair and the 2:1 lever at the same time, which necessitates a longer stay in works as likely boiler lifts and other dismantling are required. On the Thompson Pacifics, the valve gear was swapped out as individual sets, and this policy continued under Peppercorn and to the end of steam.

    It is quite clear from the loco records cards that this was what was happening - the LNER didn't use terms like "preventative maintenance" and "run to failure" at the time - these are modern terms which do accurately describe the maintenance regimes that were planned for the classes in question.

    I may have had a very small hand in it. The real credit goes to Paul Isles, Tony Wright and Andrew Hardy for their research and hard work. Certainly I have become aware of the complexities of the A2/2 decisions today and can only applaud those who have worked on them.
     
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  2. MellishR

    MellishR Resident of Nat Pres Friend

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    When I said
    that was in response to Julian's post #3597. I did not mean to suggest that Thompson's policy was a poor choice.
     
  3. Fred Kerr

    Fred Kerr Resident of Nat Pres Friend

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    Having read through some of the above comments it seems apparent that many critics are failing to appreciate the demands placed on Thompson by the demands of WWII hence the limited time and resources available to investigate and determine future developments. The fact that Thompson appears to have instituted some measure of development (which I hope your proposed book will confirm) that others followed suggests that his work has been undervalued by those who see his work as a denigration of Gresley rather than a development of Gresley albeit along a slightly different path.

    I look forward to seeing the book once available.
     
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  4. S.A.C. Martin

    S.A.C. Martin Part of the furniture

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    Understood, my apologies.
     
  5. S.A.C. Martin

    S.A.C. Martin Part of the furniture

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    The thing that really perplexes me is that the comparison betwen Thompson and Bulleid is stark. Bulleid quite literally abandoned all Gresley engineering practice and had a Pacific designed from scratch. Literally nothing of a Bulleid Pacific, bar the air smoothing, really echoes Gresley. In fact, one could cogently argue that Bulleid went out of his way to do everything differently to Gresley on the basis that he had experienced the issues with the Gresley designed locomotives. The oil bath and chain drive for the centre valve gear was one solution to the conjugated valve gear issues where maintenance was concerned - but this presented its own difficulties in practice in overhauls and stripping down.

    Thompson's solution was to use a third set of valve gear for the Pacifics and two cylinders for everything else.

    Fred, DM me later on. :)
     
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  6. 35B

    35B Nat Pres stalwart

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    I find the contrast between the two extremely interesting - and also notice the point of unity was a move away from Gresley's practice.
     
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  7. Fred Kerr

    Fred Kerr Resident of Nat Pres Friend

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    With the interesting point that both were looking to move away from Gresley's "horses for courses" policy to the Stanier "standardisation" policy. Note that Bulleid defined his Pacifics as "mixed traffic" able to power a wide range of services; whether replacing the mixed fleets ranging from tank to tender locos on the "withered arm" of the Devon and Cornwall branch lines or the express services from London to either Bournemouth / Weymouth or the West Country at Exeter his Pacifics were intended to initiate a process of standardisation in terms of the number of locomotive classes. In the same way Thompson sought standardisation by using many Gresley features but replacing the conjugated valve gear with the simpler separate valve gear arrangements to reduce maintenance. In Thompson's case he also restructured maintenance by transferring some work from depots to the centre at Doncaster - much as the GWR later concentrated diesel hydraulic repair work at Swindon to leave depots with unit replacement thus reducing down time. Also much the same as Doncaster Works doing the same (unit replacement) with its Deltic fleet leaving depots to simply undertake maintenance.

    It is an understated point that Thompson's review of locomotive maintenance that included more time at works but increased availability (if I read Simon's tables correctly) initiated a policy that served the LNER well in a principle that was continued into BR days but both this - and Bulleid's ill-fated Pacific designs - were alternative strategies to Gresley's policies. Neither Bulleid or Thompson IMHO sought to denigrate Gresley but in the changed conditions of WWII sought to take the best of Gresley and improve the weaknesses that both felt the Gresley era presented - Bulleid with a standard locomotive design to reduce the number of locomotive types and Thompson with an improved maintenance regime based around a simplified valve gear arrangement.
     
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  8. S.A.C. Martin

    S.A.C. Martin Part of the furniture

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    Absolutely. It is notable how the previously accepted shed practices of specific types of repair (e.g. lifting locos and working on bogies) became increasingly rarer, with almost all work such as that concentrated on the major works. Cowlairs effectively lost a lot of its work and one wonders if this was a result of the poor availability of locomotives that had been repaired there previously.

    Rule of thumb:

    Thompson/Peppercorn Pacifics - more works visits overall, higher availability, preventative maintenance approach.

    Gresley Pacifics - less works visits overall, lower availability, run to failure approach.

    These are not absolutes - these are general observations of trends in the statistics I have collated.

    Totally agree. But again - Bulleid stepped away from the Gresley designs almost entirely.
     
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  9. S.A.C. Martin

    S.A.C. Martin Part of the furniture

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    I've been told we've been mentioned on one of the internet's infamous model railway forums. We've hit the big time everyone! However I would like to refute any assertions that much, or most, of this discussion has been "acrimonious" (Really?) On the contrary: this thread remains one of the most thoughtful, robustly peer reviewed and interesting threads out there.

    I remain grateful for everyone's help in getting to the nub of the issues and, for the most part, contributing in meaningful, thoughtful, constructive manners. This presents the thread's eighth year of discussion and I hope to bring my part in it to a close by finally publishing the long promised book. We are getting ever closer.

    The reason for our mention on the forum is no doubt in light of the Hornby announcements yesterday. I can claim only a very small role to play in the announcement of the Thompson A2/2 and A2/3 models, having made some contributions to the Hornby researchers towards them. By far more worthy of our thanks are Paul Isles, Tony Wright and Andy Hardy.

    It is of immense pride that I see one of the first new releases will be no.500, "Edward Thompson". I would like to think I have done some good in highlighting the new evidence available to us to be better informed about his time as CME, and his work for the LNER.

    And if anyone would like to ask as to why the first standard Pacific was given the name "Edward Thompson" - be in no doubt, it reflects a long career with the LNER from 1923 to 1946, having worked under Gresley until 1941. It reflects that he was taking over the CME role during the most difficult years of the second world war, and with his team of designers, assistants and the staff of the L.N.E.R., turning the companies' own fortunes around. It is reflective of a man, much respected by his board, and chairman, and by his subordinates.

    Be in no doubt: the naming of the locomotive (which Thompson had no part to play in) was out of respect for a hard working man who did his duty.

    Let that be the end of it.
     
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  10. MikeParkin65

    MikeParkin65 Member Friend

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    Ha - sorry that was me. No offence intended although I think you'll agree this thread has been quite a roller coaster and a little heated at times. And now it all seems to be starting up again over on RMWEB
     
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  11. S.A.C. Martin

    S.A.C. Martin Part of the furniture

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    No worries Mike! I don’t go on RMweb anymore and haven’t for some time. I wasn’t given your name specifically, for clarity.

    Heated? Oh definitely, and robust too. But that’s actually been one of its positives. We’ve come a long way from the days of “Thompson rebuilt Great Northern out of spite” happily.
     
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  12. MarkinDurham

    MarkinDurham Well-Known Member

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  13. clinker

    clinker Member

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    Did Bulleid not use unified drive? I'm afraid that I still remain unconvinced of the advantages of divided drive with three cylinders.
     
  14. Spamcan81

    Spamcan81 Nat Pres stalwart

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    Bulleid stepped away from Maunsell too, and just about every other CME for that matter.
     
  15. Spamcan81

    Spamcan81 Nat Pres stalwart

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    Yep, everything drives the middle axle.
     
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  16. huochemi

    huochemi Part of the furniture

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    I guess one answer is that you don't have to work around the limitations that a steeply inclined and set back cylinder gives rise to.
     
  17. clinker

    clinker Member

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    Sorry, still not convinced, surely assuming equal length connecting rods then unified drive would put all three cylinders the same distance from the driven axle? I can see how the middle cylinder may need to be inclined to clear the bogie pivot, but that would only involve a few degrees, whereas divided drive to the first driving axle and equal length would put the middle cylinder ahead of the outer cylinders, or involve the outer cylinders being set back, as with both Thomson and Peppercorn designs (Also GWR fours) The middle cylinder may still need to be inclined in order to clear the bogie pivot. If divided drive and equal length were used to the third driving axle then the middle cylinder would need to be set back and even more inclination needed in order to clear the second driving axle.
     
  18. huochemi

    huochemi Part of the furniture

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    You have to clear the leading coupled axle, unless you want to drive everything onto the leading driving wheel, which causes its own challenges.
     
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  19. S.A.C. Martin

    S.A.C. Martin Part of the furniture

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    Agree.
     
  20. clinker

    clinker Member

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    Sorry, but these are points that My last post was covering, the middle cylinder driving the middle axle involves the cylinder being mounted forward, and still having to clear the bogie pivot, and driving the third axle would involve both setting back and clearing the second coupled axle,hence more inclination, unless different length rods are used, which Thompson certainly would never have done, as I have said, I remain unconvinced about alleged advantages of divided drive.
     

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