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LBSCR and GWR valve gear?

Discussion in 'Steam Traction' started by Jimc, Feb 6, 2021.

  1. Dunfanaghy Road

    Dunfanaghy Road Member

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    I am pretty sure that the Derby model could be set up for any combination of stroke and valve events. I guess they set it up, turned it over and judged whether it had hit the spot!
    It wasn't small - about 6 to 8 feet long, mounted on the wall.
    Pat
     
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  2. andrewtoplis

    andrewtoplis Member

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    Does it still exist? Sounds amazing
     
  3. Dunfanaghy Road

    Dunfanaghy Road Member

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    I saw it (or something very similar) in the Silk Mill Industrial Museum in Derby. When it reopens I mean to go back. (I have happy memories of the old O-gauge layout "Kirtley" in the old museum in the Wardwick.)
    BTW I think the term 'model' has caused some confusion. It was a working, drawing office, instrument, not a fine piece of model engineering.
    Pat
     
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  4. jma1009

    jma1009 Well-Known Member

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    If the LBSCR bought it, Marsh didn't learn anything from it, and I doubt Basil Field needed it anyway.

    If it was used for 'Bessborough', as the only Marsh loco with Walschaerts valve gear, it wasn't needed for Jim's suggestion, as the loco had inside the frames steam chests (with piston valves) using rocker arms.

    The LBSCR never built any locos with outside steam chests whether slide valve or piston valve.

    'Bessborough' was a one off.

    If you want to increase the valve travel via rocker arms you don't need a £150 contraption from the GWR!
     
  5. Jimc

    Jimc Part of the furniture

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    Isn't that a tad simplistic? I think you do need a piece of apparatus. Lets assume what is involved is a piece of kit capable modelling the valve events when all the variables, lap, lead, travel etc are changed. Lets say Marsh has heard of the advantages of say long travel valves, although it could be something else, there are books, ARLE meetings, any number of sources where he may have picked up an idea. Whatever the source lets say he's picked up the concept of doing something significantly different, not just the small iterations in design which was usual practice.

    He isn't going to say to his staff, OK, lets increase the valve travel by 25% (or whatever), at least not if he's any kind of engineer. What he's going to want is to establish the best settings for what he thinks is needed, which involves running all sorts of permutations. So it could be done either as a paper exercise, which would be a massive job involving hundreds of drawings, or it could be done using the modelling apparatus. From what little I understand of the subject from looking at Don Ashton's pages Walschaerts gear is very complicated to design because everything affects everything else.

    Anyway, unless someone produces evidence the sale was cancelled, whether he needed the apparatus or not it certainly looks as if he bought it.
     
  6. jma1009

    jma1009 Well-Known Member

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    I don't see any evidence that Marsh used or learnt from a valve gear model purchased from the GWR.

    The H1 Atlantics had slide valves with loco links direct drive. The H2s had piston valves inside admission unless I am mistaken. If I am correct on this, the H2s required modifications to the link suspension to be optimal.
     
  7. Jamessquared

    Jamessquared Nat Pres stalwart

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    “Used” and “learnt from” are perhaps two different questions. Whatever the vagaries of the valve gear on Marsh’s locos as they emerged from the works, apparently the GWR sold some reasonably sophisticated apparatus to the LBSCR. The interesting question is whether there is the counter-transaction of a purchase in the LBSCR records.

    It seems to me there are three possibilities:
    1. The GWR sold something but the LBSCR never received it - which would be odd.
    2. The GWR sold something which the LBSCR received. Given the value, you would imagine it would have some longevity and, unless destroyed during the war, still be around in SR days - in which case it is also odd that someone like Holcroft seemingly doesn’t mention it. That seems odd as well.
    3. The “thing” was actually rather less notable, being something like an instructional model used for MIC purposes. But in that case, £150 sounds a huge amount of money and in any case, you’d have thought Brighton could produce its own such equipment, based on the actual pattern of its own locos. So that feels odd as well.
    I suspect a query in Brighton circles would be the place to go to see if there is any balancing record of a purchase, and if so, how it was described.

    Tom
     
  8. jma1009

    jma1009 Well-Known Member

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    Hi Tom,

    I don't find any evidence that the Marsh H2 Atlantics had their valve gear altered which suggests a fundamental ignorance of valve gear basics with Stephensons gear.

    You don't have to take my word for this - you can see what the drawings translate into real metal in Atlantic House at Sheffield Park!

    Cheers,
    Julian
     
  9. Monkey Magic

    Monkey Magic Part of the furniture

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    Does anyone know what happened to Klaus Marx's papers - I would imagine he accumulated a lot of material in writing his books on Marsh et al and that might be a place to look.
     
  10. S.A.C. Martin

    S.A.C. Martin Part of the furniture

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    I don't think it's entirely fair to pick out Marsh and the Atlantics as being an example of "not understanding valve gear".

    A C.M.E. doesn't have to be an expert in valve gears. The role of the C.M.E. is a policy maker, with ultimate responsibility for decisions taken on behalf of the railway's locomotive and other engineering: but he does not have to be an expert in any given field.

    He's responsible for meeting traffic requirements, and is expected to have the broad aspects of railway engineering down, but the detailed design work is something he is only involved with at the level of discussing, signing off and approving work done on his behalf.

    His designers/draughtsmen, engineers and manufacturers will be responsible for the detailed design and analysis.

    This is something which people continuously miss the point on. C.M.E.s are not necessarily experts in anything engineering. Their role is about responsibility, policy and accountability to the board of directors, and they are remunerated accordingly.

    The best C.M.E.s get the most out of their staff, and produce locomotives/rolling stock/etc that meets the needs of the railway. That, fundamentally, is it.

    EDIT: and besides which, the Marsh Atlantics were effectively G.N.R. in origin and modernized to meet a specific traffic requirement - which they did more than adequately. Whether the valve gear was optimized or not, they did the job asked of them and that is the acid test.
     
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  11. Jamessquared

    Jamessquared Nat Pres stalwart

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    In fixating on perceived issues with the Atlantic valve gear, I think you are rather missing the point. Regardless of what design thought went into the valve gear on any of Marsh's locos, the fact remains that the GWR recorded a sale of a model of locomotive valve gear to the LBSCR. All the possibilities (it arrived; or it didn't arrive; or it was something else entirely) are odd and somewhat difficult to understand.

    Tom
     
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  12. Jamessquared

    Jamessquared Nat Pres stalwart

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    Indeed - particularly as, rightly or wrongly, Marsh's direct experience as a draughtsman was fairly limited and seemingly only at a fairly junior level. He was selected for the role of CME because of his experience as a workshop manager, not because of his acumen as a locomotive designer.

    Tom
     
  13. LMS2968

    LMS2968 Part of the furniture

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    Most people seem to believe that the CME's job was to design new engines. It wasn't; at that time his main function was to keep the existing locomotives (and possibly carriage and wagon fleets) in good repair and be available for Traffic Department use. New design was very much secondary. He was, as S.A.C. Martin says, basically a manager and would worry more about his budget than an odd eighth of an inch of valve travel. Even the Drawing Offices work would entail more improvements to existing stock than the production of anything new.
     
  14. 30854

    30854 Part of the furniture

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    ..... and decorative beading ..... don't forget decorative beading! :)
     
  15. Jimc

    Jimc Part of the furniture

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    Its amazing how much space in the GWR loco committee minutes in the 190xs is devoted to water supply, which was the responsibility of the locomotive department. Which brings the vision of Churchward in a muddy field, arguing with a farmer over whether it was going to be 2/- or 2/6 a week to divert his stream...
     
  16. clinker

    clinker New Member

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    I thought that Brunel would have sorted that out.
     
  17. jma1009

    jma1009 Well-Known Member

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    That was a mistake on my part - I should have said instead "Brighton drawing office" instead of "Marsh".

    Why did the LBSCR pay Schmidt to set/advise on valve gear settings for the Marsh/Field I3's?
     
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  18. Eightpot

    Eightpot Well-Known Member Friend

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    My understanding is that Schmidt supplied a 'package deal' which comprised advanced thinking for the time of piston valves, valve gear and superheater. This provided the much improved and demonstrated performance of I3 No. 23 compared with the L&NWR 4-4-0 on the 'Sunny South Express' between Rugby and Brighton.
     
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  19. jma1009

    jma1009 Well-Known Member

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    So what was the point of the LBSCR buying a 'valve gear model' for £150 in 1907?

    That there is no evidence of it being used or even being received at Brighton.

    Further, if after it's purchase Marsh engaged Schmidt! To advise and to set valve gear!

    Makes no sense to me!

    And for Simon, I didn't pick on the H2 Atlantics per se; it was just the first example of many that came to mind, and can easily be referenced with the new build. I could quote other examples.

    And as to Marsh being a good Works Manager in 1907, he had 30% of the locos out of use awaiting repair/overhaul!

    Yes, I know why this happened, so don't berate me further.
     
  20. Jimc

    Jimc Part of the furniture

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    This is getting kinda surreal.
    The document in question is at Kew, RAIL 250 272, page 236. Here's a photo of the paragraph from the page. You can believe me or not that I'm telling the truth about this, but unless you've actually been through the relevant LBSCR records how would you know whether there's evidence about it? OK Holcroft doesn't mention it, but IIRC he doesn't mention anything much about how valve gear was actually designed on the Southern.

    lbscr model.jpg

    And in case you're wondering how I have access to this with Kew closed, I photographed every page of most of the GWR loco committee minute books a few years ago, and am only now going through them.
     

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