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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. pete2hogs

    pete2hogs Member

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    Direct comparison between statistics from different railways which had different organisational and documentation practices are not very enlightening. However, comparisons between classes on the same railway are of great interest.

    I never was anti-Thompson - the B1's, K1's and O1's (or more accurately the pragmatic approach to the O4's with a decision whether to renew or rebuild taken on the condition of the frames) are enough to demonstrate he was competent to be in charge of the department. And I've always liked the appearance of the A2/2's - heresy I know.

    The original premise was that the characterisation of Thompson as a petty Gresley hater was incorrect . I think that has been satisfactorily shown to be the case. Thompson, being aware of the general maintenance difficulties being encountered, had to overcome the Board's idea that all that was needed was to carry on churning out Gresley standard designs (in so far as Gresley had standards). He did so, and then proceeded to build engines generally more suited to the war and the prolonged aftermath of arrears of maintenance and shortage of skills.

    I do think he had some character flaws - as did Gresley. As in fact do we all. I have found this a fascinating discussion and I would have liked more time to research on some of the points - I have most of the relevant books and have been able to follow up to some extent.
     
    Last edited: Aug 15, 2018
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  2. S.A.C. Martin

    S.A.C. Martin Part of the furniture

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    An update on the writing.

    As some of you may know, I spent a month this year going through the archives at Kew Gardens. That month of work turned up some amazing documents and finds, one of which has led to me putting together a sort of side document which covers all of the mileages achieved by LNER locomotive classes throughout the second world war (which I intend to make available online).

    Much of the information has been directly relevant to the wider points of the book in progress, and I have been carefully extrapolating the information I require out to add to evidence in the book. It is taking me longer to do this than I anticipated (my apologies). The main bulk of the work is now complete, and revisions to the bibliography are now in progress.

    I hope to be able to produce a final draft closer to Christmas now.

    I um'd and ah'd about making wholesale changes to the book over September but ultimately I don't believe it would be fair to those waiting for the tome to delay further. My apprenticeship of course takes precedence, but I feel reasonably confident of finishing this to a good standard.

    Thank you for your continued patience.
     
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  3. PoleStar

    PoleStar New Member

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    Simon,

    I found this thread by accident and it is fascinating, as I have always thought that Thompson and his work were misunderstood and deserved to be properly and impartially studied. It is a significant piece of research and I look forward to reading the book in due course.

    I have an interest in valve gears and I have often wondered why Thompson did not convert one Gresley Pacific experimentally to a separate inside valve gear, as was apparently recommended in Stanier's report. I have read somewhere - can't find the reference - that Thompson considered Stephenson's gear for the inside cylinder but was dissuaded by Stanier. If this is correct it does cast doubt on Thompson, because the two gears are incompatible. It would have to be Walscheart's, but I think there would be clearance problems between the combination lever and the leading coupled axle, hence possibly why Stephenson's was considered. The answer would surely have been to use a Walscheart's variant with a second eccentric, as found on the Maunsell Z class and others - well established by Thompson's time.

    I hope that is food for thought, and I hope the book is a great success.

    Tony.
     
  4. Kylchap

    Kylchap Member

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    He did! It was called Great Northern. It's because of this that Thompson has been reviled (rightly or wrongly) by so many people.
     
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  5. johnofwessex

    johnofwessex Resident of Nat Pres

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    Didnt Porta suggest a similar arrangement for Tornado's inside cylinder - Gooch or Allen valve gear from memory?
     
  6. PoleStar

    PoleStar New Member

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    Deleted
     
    Last edited: Nov 11, 2018
  7. PoleStar

    PoleStar New Member

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    Interesting, I didn't know that. Porta must have had good reasons, but it is difficult to see what the advantage would have been.
     
  8. johnofwessex

    johnofwessex Resident of Nat Pres

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  9. 8126

    8126 Member

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    The link provided by @johnofwessex just says space restrictions; I would guess insufficient room for a reasonably sized combination lever arrangement (it was done on the rebuilt Bulleids of course, but they had smaller drivers, shorter stroke and all the taper on the underside of the boiler barrel). Gooch gear gives a better match to the valve events of the outside Walschaerts gear than Stephensons, being another constant lead gear.
     
  10. PoleStar

    PoleStar New Member

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    I am not sure where Porta is coming from. The Peppercorn A1 has room for a combination lever, so might as well stick with conventional Walschearts as designed. Gooch gear of course gives a constant lead, but I doubt that it would give good results with a long travel valve on a "modern" express loco. and the valve events would still conflict with the outside Walschearts. Space is more restricted on the Gresley chassis which was never designed for an inside combination lever, hence the original problem.
     
  11. 8126

    8126 Member

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    Porta's proposed scheme was a Gresley chassis layout, with many other changes besides, dressed up to look like an A1. Gooch gear was his solution to the problem of putting a third set of valve gear on a Gresley-like chassis, with its very small vertical offset between the cylinder and steam chest centrelines (they're not parallel either, on the Gresley engines or the Porta proposal, which would certainly make implementing Walschaerts a lot harder). Look at the layout drawing in the link and all will be revealed. Inside admission Walscharts in a confined space is actually a very difficult gear to get good long-travel valve events for; the rebuilt Bulleids with the Gresley-like chassis have better events from their outside gear.
     
  12. PoleStar

    PoleStar New Member

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    Fair enough, and we are perhaps getting a little off-topic, but I wonder whether Porta did any detailed work on the valve gear. Gooch gear is compact, but it has some inherent disadvantages and I would expect a Walscheart's derivative with a second eccentric to give better results and be easier to design. Maybe not - just my thoughts.

    Gooch gear I believe was originally Swindon's way of avoiding Stephenson's patents, and was generally superseded by about 1900. I can't think of many later examples but I expect someone else can....
     
  13. MellishR

    MellishR Resident of Nat Pres Friend

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    Different kinds of valve gear for the inside and outside cylinders would cause some differences in the valve events, but how much would that really matter?
     
  14. Hermod

    Hermod Member

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    Our Prophet, mr Cox describes the sound of a Caledonian class 956 4-6-0 that had two walschaerts and one stephenson as unbelievable.
    It burned coal and pulled trains for some years nonetheless.
     
    Last edited: Nov 11, 2018
  15. PoleStar

    PoleStar New Member

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    A certain amount of difference is acceptable, and may not even be noticeable, but mixing the fixed-lead Walscheart's and variable-lead Stephenson's as per Caledonian Pickersgill 956 class is not a good plan. It will work OK in full gear but as the engine is notched up, the lead on the inside cylinder will gradually increase and it will be fighting the outside cylinders, hence wasting power. Maybe someone else can explain it better, but it takes us back to my original posting - Thompson (and Pickersgill) should have known this.

    I think the point is that while it would have been feasible to convert a Gresley design to an independent inside valve gear, it would not have been simple and was not thought to be cost-effective.
     
  16. johnofwessex

    johnofwessex Resident of Nat Pres

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    What does the inside valve gear on the Z class look like?
     
  17. 8126

    8126 Member

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    Two eccentrics, one driving the base of the combination lever (which can be much shorter as a consequence and avoids the problems with having the piston and valve centrelines non-parallel). The original intention was conjugated valve gear as per the prototype N1, but it would have made the already significant overhang at the front end too much for the Civil Engineer's liking. The N1 and U1 designs both originated with conjugated valve gear and got three independent sets of Walschaerts later on, I believe of the same pattern.
     
  18. andrewshimmin

    andrewshimmin Well-Known Member

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    Apparently a lot of coal, and it didn't pull them very well. They were very handsome engines, but complete turkeys.
    Like a number of other places, St Rollox had great difficulty moving from a fleet of superb 4-4-0s to powerful and efficient 4-6-0s when the need arose. The only really good ones they had were the ex-Highland ones.
     
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  19. S.A.C. Martin

    S.A.C. Martin Part of the furniture

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    Most kind Tony. The book itself is more or less complete but - as always - I have been distracted by my current apprenticeship with Network Rail and collating some more of the Kew Gardens evidence (including creating a document on the LNER's wartime availability of locomotives). I am still looking at releasing it online to interested Nat Pres members around Christmas time with a caveat of a donation made to some of the loco groups I support.

    I would be interested to see where you read this. I have never heard anything approaching this. As far as I am aware Thompson was always in mind to use three sets of walschaerts on the three cylinder Pacifics. Indeed he was encouraged to and also for the benefits of equal length connecting rods - hence the P2 rebuilds.

    He did of course experimentally rebuild Great Northern - no.113 (later 60113) to a form developed from his 6ft 2in Pacifics (A2/1, A2/2, A2/3) albeit developing the Gresley A4 further in reality, when you look at Great Northern's setup (250lb boiler identical to A4s, frames and cartazzi setup based on the A4s - cartazzi slightly different).

    Only the Pacifics were considered for retaining three cylinders - everything else counted as small or medium sized locomotives and were therefore to be two cylinder machines.

    Most kind - so do I! But success I would judge based on whether or not it produces a greater swell of support for rethinking that which we think we know about Edward Thompson (and the other wartime CMEs).
     
  20. S.A.C. Martin

    S.A.C. Martin Part of the furniture

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    Always - wrongly. The issue is in the emotive response and the idea of it being done specifically because it was Great Northern. In summary:

    1) It could have been any of the remaining A10s - but L.A. Musgrave picked Great Northern. It was in works, it was the oldest, it was logical.

    2) There is anecdotal evidence that Teddy Windle and Thompson had a lively discussion on the name.

    My gut feeling is this is likely true, but the context potentially skewed by history. Thompson did not like names being attached to locomotives: the P2 rebuilds and his reluctance for the B1s to be named is evidence of this. Perhaps - and this is only summation on my part - the issue wasn't rebuilding the locomotive so much as losing the name. The locomotive had to retain the original number to count as a "rebuilding" when submitted for rebuilding to the LNER emergency board and the war department - the name would aid in this one suspects. But I cannot prove this, only surmise based on the documents I have seen in the National Records at Kew Gardens to that effect.

    3) Various commentary on "gresley turning in his grave", "Machiavellian campaign" etc etc

    All ludicrous when you consider Gresley rebuilt many of his own locomotives from different forms and other engineers too. Coupled with the availability problem (now clear to me after four months worth of collating the full figures for the LNER fleet) anything that could be done to improve the lot of the conjugated valve gear fleet would have been - and was at the time - welcome. Including three sets of full walschaerts it seems.

    I could go on but really we've done the Great Northern debate to death in this thread. It almost always comes down to whether you feel the LNER and Thompson cared about preservation of steam locomotives in WW2 or not. If not, then its immaterial that the prototype was Great Northern.
     

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