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Edward Thompson: Wartime C.M.E. Discussion 2012 - 2019

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

  1. andrewshimmin

    andrewshimmin Well-Known Member

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    As others have said, the Railways weren't after perfection, especially expensive perfection or long development perfection.
    Any loco which could be built relatively inexpensively, and did the job required reliably without too high maintenance cost or running cost, was a success.
     
  2. D6332found

    D6332found New Member

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    I have read somewhere a taper boiler with a Belpaire is threefold the cost of a simpler design. So such as a B1s. I think it was in the nrm papers but the cost of a new Black 5 vs a B1 would be most informative as to the accounting of this.
     
  3. Hirn

    Hirn New Member

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    Could I add? The model he made of his concept, half a generation before the Schools class emerged, while convalescing during WWI, is at Didcot.
    A 4-4-0, kept and conserved. Shown to Maunsell on Holcroft's return to work, it evidently considerably impressed Maunsell.
     
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  4. Hirn

    Hirn New Member

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    Very interesting: the height of the upper corner of British platform edges imposed a very effective limit on the diameter of outside cylinders
    that did not apply when the platform height was about the railhead - i.e. most other countries - Japan is a notable exception.
    This constrained in Britain - or would have constrained - three cylinder compounds on the Smith principle as Chapelon proposed for modern
    high power output in France.

    There were other reasons for adopting more than two cylinders than just what would go through the loading gauge.
     
    Last edited: May 28, 2019
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  5. Hirn

    Hirn New Member

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    Would be Holcroft himself. I think in one of his published books. If not - maybe implicit - in the unpublished typescript of his last book in 1990,
    with his papers in the NRM.
     
    Last edited: May 28, 2019
  6. Hirn

    Hirn New Member

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    Is that Grand who was in charge of the Western Region in BR days in the background?

    The model had not only Holcroft's original design features but an intermediate tubeplate within the boiler barrel like Chapelon's 2-12- o.
    (The feed water was led into the separate compartment so formed at the front end of the boiler & preheated by the cooler end of the tubes.
    Apart from any fuel economy achieved Chapelon commented that the boiler rallied distinctly well if refilled after the water level had been
    allowed to fall.)
     
  7. Hirn

    Hirn New Member

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    Holcroft while still on the SR had remarkably little to do with Bulleid until 1943, though when they did strike up they got on well.
     
  8. Hirn

    Hirn New Member

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    Would the Claughton as a Pacific have been too long for the existing turntables?

    It was the unenthusiasm of another department to pay for longer turntables that undid the Fowler compound 4-6-2/2-8-2
    (There are different diagrams: interestingly, one shows a long low bogie tender like a Urie one from the LSWR and the Southern,
    the other something much more compact and six wheeled. An attempt to mitigate the turntable problem?)
     
  9. 30854

    30854 Part of the furniture

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    By which logic ..... if big probs with the Claughtons centred on the bottom of the firebox, perhaps they'd have been better as Garratts. Just kidding! :)
     
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  10. Hirn

    Hirn New Member

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    The point was not that any metal had been cut but that the materials had been ordered - presumably firmly and there would be damages to pay if
    cancelled - Clayton had to talk Bulleid out of not proceeding with the Q Class as he indeed wanted to.

    This is in the unpublished typescript in the NRM. One of the numerous occasions where Holcroft enlarges on what is a bald statement in ""Locomotive Adventure" and the detail later recalled helps to establish the reliability of the earlier book.
     
  11. Hirn

    Hirn New Member

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    Grarratts are long indeed. The LMS ones without a turntable were turned though: on a triangle at one end and a marvellous semi circular reversing loop as a dive under at the other end of their carefully planned main coal haul.
     
    Last edited: May 28, 2019
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  12. RLinkinS

    RLinkinS Member

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    Not Grand but Reggie Hanks. Mr Hanks had a private 3.5" gauge railway and a fine collection of locos to run on it. Unfortunately several of them were stolen.
     
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  13. jma1009

    jma1009 Member

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    I am very sorry, but I don't understand any of poster 'Hirn''s threads today

    Cheers,

    Julian
     
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  14. andrewshimmin

    andrewshimmin Well-Known Member

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    It was seriously contemplated in the early days of the LMS.
    The LMS running dept proposed a compound express double-atlantic to Beyer Peacock, who counter-proposed an express double-pacific (superficially similar to the 5'3" ones they supplied to Brazil, although those were originally 2-6-2+2-6-2 and were modified later in Sao Paulo)
    Both are described and illustrated in Robin Barnes' "Locomotives that never where", which I highly recommend.
    The BP 4-6-2+2+2-6-4 in particular would have been a magnificent beast.
     
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  15. andrewshimmin

    andrewshimmin Well-Known Member

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    There are various different diagrams: some of them are Hughes' proposals from the pre-Fowler era.
     
  16. bluetrain

    bluetrain New Member

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    Thank-you for your thoughts above. There is no doubt that the high station platforms in Britain and Ireland acted as a significant constraint on locomotive designers who wished to use large-diameter outside cylinders.

    There are some examples where engineers managed to incorporate surprisingly large cylinders in spite of the difficulties. Way back in 1888, the LSWR loco engineer William Adams rebuilt one of his outside-cylinder 4-4-0s as a 2-cylinder compound, replacing a standard 18-in cylinder with a new low-pressure cylinder of 26-in diameter. That is only slightly less than the 680mm (26¾-in) outside cylinders on Chapelon's famous 3-cylinder compound No 242A1. The trick was that Adams 4-4-0 cylinders drove onto the leading coupled axle, with the connecting rods placed inside the coupling rods. That was a feature seen on many outside cylinder 2-4-0s and 4-4-0s. It meant the cylinders were closer together and the engine's overall width kept down.

    The Midland 3-cylinder 4-4-0 compounds also had the connecting rods inside the coupling rods. In spite of large 21-in diameter outside low-pressure cylinders, the overall engine width was only 8-ft 6½-in. There was scope, had the Midland or LMS so wished, to enlarge the design into a 4-4-2 or 4-6-0 with the same layout and to enlarge the cylinders, while still keeping within the troublesome loading gauges prevailing on some LMS sections.

    The LMS Hughes "Crab" 2-6-0 also had large 21-in outside cylinders, placed very high to keep them away both from platform edges and from the sideways movement of the pony-truck frame. The "Crab" could never have been an entrant in a locomotive beauty competition, but it was a very successful and long-lived type, with some very clever and careful design by Hughes and his staff to keep those big cylinders well within the loading gauge.

    In his book "World Steam in the 20th Century", the British Rail senior locomotive engineer ES Cox discusses the impact of loading gauge width restrictions on design, with particular reference to the large French compounds. The French, rather like Francis Webb of the LNWR, had tended to put the large low-pressure cylinders inside, between the frames, but faced increasing difficulty with crank-axle and bearing arrangements. The alternative of putting the large low-pressure cylinders outside, as in 242A1 and some others, eased the problems between the frames, but even the more generous French loading gauge was becoming a constraint if outside cylinders of the desired size were to be provided while also allowing adequate width for the connecting and coupling rod bearings.

    You rightly point out that there were more reasons than just the loading gauge for going to more than 2 cylinders. And that brings us right back to a central theme of this thread, namely the differences in locomotive design policy between the LNER's locomotive engineers. Gresley had become a very strong advocate of 3-cylinder propulsion and had extended its use to medium power locomotives rather than just the very largest. He cited reasons such as lighter reciprocating parts, reduced hammer-blow and more uniform starting effort. Thompson by contrast favoured 2-cylinder propulsion for general use, with 3-cylinders only on the largest and most powerful engines. Thompson's views were undoubtedly strengthened by the engine maintenance difficulties being experienced during WW2. His successor Peppercorn also adopted the Thompson policy, albeit with less enthusiasm for rebuilding existing Gresley 3-cylinder classes.
     
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  17. jma1009

    jma1009 Member

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    Hi 'bluetrain',

    The LBSCR Baltic tanks had 22" dia outside cylinders, and the LBSCR was not known for a generous loading gauge, which rather drives a coach and horses through your otherwise well reasoned post.

    Cheers,

    Julian
     
  18. bluetrain

    bluetrain New Member

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    Some of the LSWR Urie 4-6-0s also had 22-in outside cylinders - which were kept within the 9-ft wide loading gauge by insetting the frames by 3 inches from a point just in front of the first coupled wheels. A number of other engine types had a similar inset - for example the Great Central/ROD O4 2-8-0 or the Great Northern Ivatt Atlantics.

    I do not know for certain how the frames of the LBSC Baltic tanks were arranged, but I strongly suspect that they also had a frame inset at the front. Do also remember that in the early 20th century, the frames for the larger engines could not always be manufactured in one piece. Some had extension sections rivetted on, usually with the front section rivetted to the inside of the main section.

    Conversely, I believe that I have read (although I can't remember where) that the two larger French compound Atlantics purchased by the GWR (Nos 103/4) had the front section of the frames splayed out, in order to accommodate their large inside cylinders (23½-in dia).
     
  19. Jimc

    Jimc Well-Known Member

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    It wasn't especially wide, but it was tall - more so at the top corners than the GWR gauge. Would have been good for modern container traffic! Irrelevant for cylinders of course. See the link below for a good number of the pregroup gauges. The thing is the platform to rail clearance had to be pretty much standard, there was never going to be a lot of variation.
     
  20. Hermod

    Hermod New Member

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    On standard gauge locomotives with connecting rods outside coupling rods 6 feet 8 inches is minimum cylinder distance.Front driver driving with conrods inside coupling rods can come down to 6 feet three as on Midland compounds.
     

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