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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. Jimc

    Jimc Part of the furniture

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    But is a simplistic point of any value at all? We're all well aware that there's no point in having half the number of moving parts if they need attention twice as often.
     
  2. Sheff

    Sheff Resident of Nat Pres

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    Chaps, I really didn't intend to raise anyone's hackles. I have no illusions about the wartime reliability issues and Thompson's solution (as I stated, I'm talking post WW11) IMHO the 2:1 gear has the distinct advantages of being external and having fewer moving parts so prep and maintenance are simplified, leaving just the slide bars and big end between the frames. The advantages on an A4 are, I image, somewhat limited by the accessibility due to the casing. However, with modern sealed bearings I think the advantages are clear. I have a downer generally on internal valve gears from an operational point of view. GWR were the obvious culprits and the Princesses amongst the worse offenders. For me, Gresely/Holcroft gear and the Duchesses had the best arrangement for multi cylinder locos. along with DoG. Bulleid's oil bath was another wartime attempt to reduce prep time, but in the end Gresley's gear gave you much of that advantage without all the disadvantages regarding maintenance access. Peace and goodwill :)
     
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  3. Jimc

    Jimc Part of the furniture

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    Not really a question of hackles.

    I do believe we enthusiasts are prone to over simplistic evaluations of what are actually quite complex engineering decisions. As I said, the question posed, which is cheaper to maintain, is a very useful, even vital one if we want to understand why the various decisions were made. But if we then reply to those questions with over simplistic answers that don't actually take into account the reality of the situation then we are going to deceive ourselves.

    Off hand possibilities that occur to me are things like how much lubricant was used, how much the lubricants cost, whether special lubricants had to be stocked that would otherwise be unnecessary, how often failures occurred on the road, and whether they'd disable the locomotive, whether and how many bearing surfaces would run between general overhauls without attention... Doubtless there are loads more. Consider Tornado's recent failure caused by a seized valve. What would happen if the same thing occurred on a conjugated gear locomotive. Would there be less damage or more? Would it be easier or more difficult to get the locomotive off the running line? And of course very often the information wasn't even available then, let alone now, so the engineers had to take a best guess on what information they did have.

    This is something I learned the hard way writing my book. Early drafts have several really logical theories about why things were done or decisions made that had to be discarded when a new piece of evidence turned up that proved or at least suggested they were false. Sometimes I found it rather hard to discard pet theories that got exploded when I found another source. Sometimes the sources seem to contradict too...
     
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  4. sir gilbert claughton

    sir gilbert claughton Well-Known Member

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    the V4 will be asked to produce neither high power , nor high speed
     
  5. Hermod

    Hermod Member

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    What is worse is it cannot be full BR Rugby and road tested, to answer :
    was Thompsons B1 better than Gresleys V4?
    Very important question.
     
  6. Jamessquared

    Jamessquared Nat Pres stalwart

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    What does “better” mean in that sentence? Once you assume both could shift the loads they had been designed for, you start getting into questions of capital cost (and what the cost of capital was), per mile repair cost, per mile running cost, availability etc. And then those numbers, even if available, would be skewed by the fact that one class had 400 members and one had 2, affecting the real cost of ownership (because of cost of maintaining spares etc - total cost of ownership will tend to favour the bigger class just because it is bigger, hence the reason small non-standard classes tended to succumb to an early demise).

    Bottom line is “which was better” is at this remove almost impossible to answer, but if you wanted a genie to grant you some hitherto unknown data with which to try, results from Rugby wouldn’t be where I’d start looking.

    Tom
     
  7. jma1009

    jma1009 Well-Known Member

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    I suppose to add a bit of objectivity to the debate, Maunsell decided to convert the Holcroft conjugated gear locos and whilst Holcroft was still one of his 3 senior officers, and Holcroft was pretty sanguine about it in print. It was a very clever mathematical and geometric devise that Holcroft understood perfectly. Maunsell retired well before Holcroft, and Holcroft then served under Bulleid. (End of objectivity).

    Bulleid never showed any interest in his ex-boss Gresley's conjugated gear, or ever tried to re-apply Holcroft's conjugated gear to SR locos (though I consider personally Bulleid had a very poor understanding of locomotive valve gears and smokebox draughting).

    One could easily form an argument that prior to WW2, Maunsell had decided to abandon Holcroft's conjugated gear, though one might add the locos concerned were designed to be easily so converted. E S Cox could easily have referred to this in his report to Thompson as an example of one of the 'Big Four' ditching the conjugated gear, but did not do so. (Probably he was not that much in touch with SR loco matters under Maunsell).

    Cheers,

    Julian
     
  8. Hermod

    Hermod Member

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    Mr Cox (guiding star of my Youth) stated somewhere that he thougth B1 a sounder locomotive than the V4.
    The search has to start somewhere and comparing coal in/traction out is a first good test.
    The B1 report from Rugby exists.
    In Germany it was baureihe 38 against baureihe 23 and the P8 won.
     
  9. paullad1984

    paullad1984 Member

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    Well with a replica in the wings well find out by comparison with the two B1s
     
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  10. Fred Kerr

    Fred Kerr Resident of Nat Pres Friend

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    But Mr Cox was familiar in an environment in which 2-6-2 was a Class 2 tank locomotive and the 4-6-0 was the mixed traffic design hence Thomson was following familiar lines; Gresley was doing the same but his familiar ones emanated from the success of the V2 2-6-2 which had proved the concept of 2-6-2 tender locomotive as a mixed traffic design. Whilst not expert in the field of engineering I begin to suspect that Cox was to locomotive design what Nock was to authorship - is that fair I wonder ?
     
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  11. MellishR

    MellishR Resident of Nat Pres Friend

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    Is it known why Maunsell converted the Holcroft conjugated gear locos? That was before the changed circumstances of WWII when the Gresley version suffered from poor maintenance.
     
  12. Jimc

    Jimc Part of the furniture

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  13. RLinkinS

    RLinkinS Member

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    I think you are being unfair to E S Cox. I have read several of his books and, as an engineer, I believe he had a very good understanding of locomotive design. He had started out "on the shop floor" and worked for and with a lot of very talented locomotive engineers. He also admits at times that he did not understand problems that were occurring. The LMS had worked up an outline scheme for a 2-6-2 tender loco in 1942 that was obviously inspired by the V2s. I think that this outline design pre-dated the 2-6-2 Ivatt tanks.
     
  14. Jamessquared

    Jamessquared Nat Pres stalwart

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    Re 2-6-2 tender engines. There was a 1934 proposal from Maunsell for one on the SR, with the wide firebox Belpaire boiler from the proposed (unbuilt) pacific, four cylinders, standard flush-sided 5,000 gallon 8-wheel double-bogie tender. The design was rejected after the Civil Engineer put quite onerous restrictions on where it could run. From the outline dimensions given in Bradley it would have had the highest tractive effort of any conventional loco ever built in the UK (over 45,000lbf) though I have a hunch that he has made a mistake either in the quoted cylinder diameter or the number of cylinders or both; a figure of about 35,000lbf seems more likely.

    From the line drawing, it would have been an imposing loco.

    Tom
     
  15. Jamessquared

    Jamessquared Nat Pres stalwart

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    From the relevant volume of Bradley, talking about the prototype N1, which was outshopped in March 1923:

    "By this date [mid 1925] trouble was being met from the derived valve gear where back-lash and loss of lever rigidity was causing the centre valve to over-run when working at speed in full gear. The clearance between the valve head and the cover was 5/8", but nevertheless on inspection there was clear evidence that contact was occurring regularly. In part the loss of rigidity was the result of poor maintenance of the floating lever's grease lubricated bearings, but even after they had been renewed some contact with the valve cover was still made when coasting in full gear. Accordingly Ashford Works removed the derived gear and fitted a third set of Walschaerts motion in October 1931. At the same time all three cylinders were renewed and the number altered to 1822."​

    So poor maintenance still cited as a factor.

    Tom
     
    Last edited: Jan 18, 2019
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  16. RLinkinS

    RLinkinS Member

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    The weight diagram of the LMS proposal is shown on page 130 of "Chronicles of Steam". I has 3 cylinders, a shortened Duchess boiler with 40 square feet grate area and 6' driving wheels and a tractive effort of 35250 lbs. It is very similar in size to the Maunsell proposal. The LMS would have found them very useful and would have been better to build some of these rather than Black 5s for the heavier duties.
     
  17. 35B

    35B Nat Pres stalwart

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    Worth noting that the latest Backtrack includes part 1 of an article by LA Summers entitled “A Revisionist View of Edward Thompson”.


    Sent from my iPhone using Tapatalk
     
  18. S.A.C. Martin

    S.A.C. Martin Part of the furniture

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    Yes. Having now read the article in question, my initial response confirmed by further re reading and talking it out with some friends (without railway links so as to get some level of objectivity).

    The article is not “revisionist”.

    It is however, speculative and in several ways, malicious.

    If Thompson were alive several points could be likened to libel.

    Having spoken to the late Dorothy Mather once on his disapproval of her (and she was very restrained in her responses - she made clear however her own dislike for Thompson, understandable given Peppercorns and Thompson’s working relationship), I can entirely rebuttal the comment made in the article that Thompson disapproved of her marriage to Peppercorn because he (Thompson) was interested in her (!) but that a more conservative and atypical Christian view of age versus remarrying was at work in that.

    I’m afraid there’s nothing revisionist about LA Summers work. It is a further example of poor research coupled with rampant speculation.

    Suffice to say, I will be writing to backtrack magazine to provide a rebuttal and evidence.

    He does get one thing abundantly right however - Colonel Rogers book on Thompson and Peppercorn is definitely not to be recommended as a reliable source for study on Thompson or Peppercorn.
     
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  19. Monkey Magic

    Monkey Magic Part of the furniture

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  20. S.A.C. Martin

    S.A.C. Martin Part of the furniture

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    The only way the writer could have stolen a march on me was to do any research outside of the tired and tested already known sources.
     

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