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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. 35B

    35B Nat Pres stalwart

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    I think that's unfair. @huochemi may not be the only one to question the focus on two different types of 3 cylinder design as the answer to the availability issues faced by the LNER. Much as I like - and recognise the validity of - that Dilbert strip, I'm holding my opinion on ET's behaviour. But if we step back from the specific question of the conjugated valve gear, one has to ask why the question of "2 cylinders or 3" wasn't asked. I can come up with ideas - for and against the commissioning of that report - as to why, but am interested in what questions were - or were not - asked, and why.
     
  2. oldmrheath

    oldmrheath Well-Known Member

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    I think it's interesting from that table that the K4's were achieving very similar average loco mileages to the K2's.

    I understand that the K4's were able to do work over the West Highland which would have required double-headed K2's , so it might be interesting to know how many K2's would have been needed to do the work the small K4 class did, given the relative availability of the two types?

    Jon
     
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  3. S.A.C. Martin

    S.A.C. Martin Part of the furniture

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    Am I in an alternate reality right now?

    Thompson literally did exactly that. The question was answered - 2 cylinders instead of 3 - for all but the largest classes.

    The only class on the LNER which had three cylinders but not conjugated valve gear was B16/1.

    Therefore it can only be a question of 3 cylinders and conjugated against 2 cylinders - you cannot remove conjugated from the equation, it is literally all there is, in terms of 3 cylinders.
     
  4. huochemi

    huochemi Part of the furniture

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    Forgive me, I was not aware you had posted the report in full. Perhaps you could repost or send me a copy privately?
     
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  5. S.A.C. Martin

    S.A.C. Martin Part of the furniture

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    That’s okay, I’ll send it shortly. My apologies for the frustration. It’s been a wearying day elsewhere!
     
  6. 35B

    35B Nat Pres stalwart

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    Thank you - my expertise on the LNER fleet is limited, so that point had passed me by.
     
  7. Jamessquared

    Jamessquared Nat Pres stalwart

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    Simon - it was the Maunsell Mogul family, the chronology of the three cylinder locos was as follows:

    Class N1 2-6-0
    1 loco, built 1922 with conjugated valve gear, rebuilt 1931 with independent valve gear.
    5 locos, built 1930 with three independent sets of valve gear.

    Class K1 2-6-4T
    1 loco, built December 1925 with conjugated valve gear, rebuilt (as 2-6-0 class U1) June 1928 retaining conjugated valve gear, rebuilt 1930 with independent valve gear.

    Class U1 2-6-0
    20 locos, built 1931 all with three independent sets of valve gear.

    Class Z 0-8-0T
    8 locos, built 1929 with three independent sets of valve gear.

    Class W 2-6-4T
    5 locos, built 1932 with three independent sets of valve gear

    The class Z is interesting, in that it was designed to use conjugated valve gear, but the civil engineer objected to the large overhang at the front (essentially it meant the leading wheels would not invariably depress fouling bars at the point the front of the loco became foul at a set of points). So before construction, the class was redesigned with three independent sets of valve gear, of which Holcroft says "provision having been made in the original design for such a contingency". The inside valve gear design was then re-used on the later series N1, U1 and W classes.

    All that actually raises more questions to me than it answers! It seems there was something of a change of heart on the SR between 1929 - 1930 about conjugated valve gear, which was in any case not widely used. One reason put about for the switchover to three sets of valve gear was that the weigh saving advantage of the conjugated gear was no longer needed due to upgrades of the p/way particularly on the Southern's Eastern section. It is notable that Holcroft (who naturally felt a somewhat proprietorial interest in the design) and Clayton (who was on record as perceiving disadvantages, as for example in the in the discussion of Holcroft's 1918 paper on three cylinder locos) had differing views on the efficacy of the gear. Holcroft notes, about the second (1931) batch of N1s: "An inside valve gear similar to that on the Z class was provided, notwithstanding that this meant some sacrifice of the rigid horizontal staying of the frames and impaired accessibility for oiling, since engines had to be brought over a pit." Reading between the lines, you could read that as a slightly veiled comment that Holcroft wasn't altogether in favour of that design modification over the original design.

    Apart from that, there was quite a lot of testing done on the SR between the two and three cylinder locos, but it primarily seems to have been a comparison between two and three cylinders, and not an analysis of conjugated vs. independent valve gear.

    Tom
     
    Last edited: Sep 9, 2019
  8. Eightpot

    Eightpot Resident of Nat Pres Friend

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    Simon, I'm not sure that your K4 to K2 comparison is really comparing 'like for like' for 1942. The K4s were specifically designed for the West Highland Line and by being capable of giving short bursts of high power - this being reflected in their tractive effort of 36,600 lb with a boiler pressure of 200 psi. In comparison, the K2s had a T.E of only 2/3 that of the K4 at 23,400 lb with a B.P of only 180 lb. Granted that on the flatter and speedier stretches at the Glasgow end of the line, I've seen somewhere to the effect that with only 5' - 2" wheels they were flogged a bit, the K2s being 5' - 8". All were based at Eastfield in 1942 apart from 3443/61995 shedded at Fort William. It is only reasonable to believe that in view of the harder work they were doing compared to the K2s that there would be more maintenance needed, and more time out of action.

    The K2s do seem to have had an easier life and from Yeadon's Register I can only find 10 K2s that were shedded at either Eastfield or Fort William for the whole of 1942. Another 7 were transferred to Eastfield later in 1942, 61772/4 sometime in September, and 61776/84/5/6/92 sometime in October, but 61785 transferred away again to St. Margarets on 3/12/42. The only other sheds to have them were St. Margarets and Thornton Junction, so I think it fair to say that they had a much easier life near the Scottish east coast than the K4s did on the West Highland Line. This has to be taken into account when it comes to maintenance and downtime. Would it also be fair to say that in the absence of a K4, it would need two K2s to do the job? I have seen several photos of double-headed K2s on the WHL.
     
    Last edited: Sep 9, 2019
  9. ross

    ross Well-Known Member

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    The problem is, none of us on here, even the most experienced Gresley locomotive crewman, does not know what it is to maintain locomotives for everyday service during the conditions prevalent during the war. We've read about it, we might have watched a Pathe film about "keeping the wheels turning" but we've not experienced it.
    I have experienced a sustained period of conflict (but didn't play with steam locomotives), and it is impossible to describe to people the slow slide into madness. The shortages of commonplace or essential supplies, the extraordinary operating methods you adopt to eke out such supplies, and it seems reasonable because everyone else is doing it. "Madness is the new normal" was a popular phrase....
    But the guys on the NYMR who operated an A4 on a daily basis have never spent the night sleeping fitfully in a pig ark and the bottom of the garden because of an air raid, then headed for Grosmont in the early dawn wondering if the shed roof has been blown to bits by a passing heinkel
     
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  10. huochemi

    huochemi Part of the furniture

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    I suspect that is where our mutual difficulty is. Unless you can compare Gresley gear against another three cylinder arrangement, it seems to me difficult to point the finger at the Gresley gear, which lends weight to ET' s apparent idee fixe on this point. The more obvious conclusion (to me) would be that two cylinders are better than three for maintainability, and clearly Gresley gear was not that bad as it lasted in front line service to 1966.
    But why would those conditions not affect maintenance of three sets of valve gear?
     
  11. jma1009

    jma1009 Well-Known Member

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    The ex-LBSCR in SR days got on very well with providing trains in WW2, and John Pelham Maitland got a 'gong' as a result.

    The LBSCR lines had to deal with Dunkirk and much else besides, and was pretty much in the 'front line'.

    I personally fail to see why the LNER was as affected by WW2 as the SR, and why Thompson should have elevated status as proposed by Simon. Seems a bit blinkered to me.

    Cheers,
    Julian
     
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  12. Eightpot

    Eightpot Resident of Nat Pres Friend

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    I think the best example for a comparison would be the Gresley rebuilt 2 : 1 fitted B16/2 and the three sets of Walschaerts gear fitted B16/3 by Thompson. Got anything to cover these variations, Simon?
     
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  13. Jamessquared

    Jamessquared Nat Pres stalwart

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    I tend to agree with @huochemi here. The availability figures will certainly show the worsening locomotive situation as the war developed, and can also potentially shine light on differences between two and three cylinder locos. However, since almost all the three cylinder locos had conjugated valve gear, you cannot readily say how much of the lower availability was attributable specifically to the valve gear, and how much just to being a three cylinder design.

    It's worth considering that a multi-cylinder loco will inherently take longer and cost more to overhaul, for no other reason that there is "more of everything". Three sets of valve gear to take down, refurbish and put back up will take longer than doing the same with two sets. So you don't necessarily need the precise layout of the valve gear to understand a lower availability for three cylinder locos.

    As an aside - and I haven't got the figures to hand, but can get them tonight - but amongst the Manusell moguls, through the 1930s the three cylinder N1 and U1 had about 5 - 10% lower mileages between overhauls relative to the two cylinder N and U class. That is with three sets of conventional valve gear and before any drop off in maintenance standards occasioned by the war. So if they run lower mileage between overhaul and are then incrementally more time consuming to overhaul, the availability of a three cylinder design will inevitably be worse than a comparable two cylinder design. Where I think you need to focus is whether, amongst the general drop off during the war, whether the three cylinder designs declined more than the two cylinder ones.

    Tom
     
  14. 35B

    35B Nat Pres stalwart

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    You may want to consider the nature of the companies, the duties required of them, and the condition of their fleets beforehand - remember, the LNER had been run on a shoestring for a long time, something obscured by the high profile of its expresses.

    I also note that Simon is considering Thompson, whose reputation is chiefly defined in relation to his predecessor Gresley. I’m unclear how much, in those terms, is to be gained by expanding that study to consider the relative performance of all fleets. There’s certainly a question in respect of the Stanier/Cox Report over the real significance of the statistics, and whether the primary issue was conjugated valve gear or the number of cylinders, but that is to qualify understanding, not fundamentally change an assessment. In any case, the answer to that question can only ever be along the lines of “had they had the benefit of today’s hindsight then...”


    Sent from my iPad using Tapatalk
     
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  15. Hermod

    Hermod Member

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    Or B17 versus two outside cylinders and more or less samme rpm like Robinson 2-8-0
     
  16. huochemi

    huochemi Part of the furniture

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    No worries. Do you have sufficient data to compare the Q7s (which I think had three sets of independent valve gear) with say the Q6s?
     
  17. S.A.C. Martin

    S.A.C. Martin Part of the furniture

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    I will respond to all requests that I can shortly.

    I feel strongly that we are overlooking a vital part of the Cox Report which states the below:


    So taking away from that:
    • 652 conjugated valve gear LNER engines suffered 10 times as many hot bearings on the inside as outside big ends in 1941.
    • The number of hot bearings suffered by these 652 engines was 6 times as many as those suffered by the 591 3-cylinder engines on the LMS (none of these are conjugated valve gear locomotives) in the same period. The report did not give the stat for that failure.
    Two years ago I approached a gentlemen who remains an expert in LMS matters and he furnished me with the following stat - the number of big end failures for 1941 was 67 for the LMS 3 cylinder engines. 6 times 67 is 402 failures.

    In my original lecture that I gave last year, I used this pie chart - it's not a particularly useful chart now, with the additional information we know on the availability figures, but it is useful for seeing what the proportion of the fleet which failed with big end failure in just that year, 1941.

    upload_2019-9-10_10-2-38.png

    Now, whether or not you put the end result - middle big end failure - down to walschaerts valve gear or not, we cannot deny that there is a comparison made there between one fleet which is conjugated, and one which is not, of similar numbers.

    Whether they are similar types is another matter, of course, and it's worth having that discussion as to whether comparing mostly LMS 4-6-0s with three cylinders is actually comparable to the variety of wheel arrangements the LNER had with three cylinders.

    I find it an interesting comparison, nonetheless.
     
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  18. S.A.C. Martin

    S.A.C. Martin Part of the furniture

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    I believe I should do, I will look today when I am able.
     
  19. S.A.C. Martin

    S.A.C. Martin Part of the furniture

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    I do for B16/1 and B16/2 - but I haven't as yet put it into the spreadsheet. I will do so when I can and will share accordingly. I am unsure if I have anything for B16/3 - it may be that they were converted too late to get anything into the period that I have availability figures for, but I will check.

    One thing is clear though from a quick glance at the figures - B16/2 looks considerably worse than B16/1 for availability.
     
  20. S.A.C. Martin

    S.A.C. Martin Part of the furniture

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    I have all of the B classes done for 1942 so will copy a selection over for interest's sake later on.
     

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