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Valve Gears - please explain to a Numpty

Discussion in 'Steam Traction' started by johnofwessex, May 20, 2016.

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  1. Beckford

    Beckford Guest

    Brilliant! Thank you.
     
    Beckford, May 21, 2016
    #21
  2. johnofwessex

    johnofwessex Resident of Nat Pres

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    Thank you everyone

    Now to think of some more questions!
     
    johnofwessex, May 21, 2016
    #22
  3. Jimc

    Jimc Part of the furniture

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    Jimc, May 22, 2016
    #23
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  4. RLinkinS

    RLinkinS Member

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    If you follow links on Don Ashton's website there are computer simulations of Walschaerts' and Stevenson's valve gear available. It is quite informative to watch the animations. Although Don is mainly concerned with the design of valve gear for models he, and others, have put a lot of effort into studying valve gears. I used the simulation programme created by Dr Allan Wallace and entered the dimensions for the Southern moguls. This gave an analysis of the valve events which matched that on the valve gear drawing so I am convinced it is an accurate model. I am also extremely impressed by the quality of the original design, especially as they probably worked out the valve events using a wooden model.
     
    RLinkinS, May 22, 2016
    #24
  5. LMS2968

    LMS2968 Part of the furniture

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    Mr Ashton's suggestion that the basis for 4767's construction is unknown is not consistent with Eric Langridge's story as related above, and since Mr Langridge was a senior draughtsman at Derby DO at the time, there is no reason to doubt his words.

    I certainly would not though challenge Mr Ashton's analysis of the gear as applied to the loco.
     
    LMS2968, May 23, 2016
    #25
  6. Jimc

    Jimc Part of the furniture

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    I think he actually said that little appears to be known. It would seem the Langridge comment was unknown to him when he wrote that.

    A lesson, perhaps, of the Thompson thread is that there is valuable information scattered about in all sorts of obscure and unlikely sources, and perhaps only if you gather a large body of reasonably well read people do you have a chance to capture them all. You then have the problem of disentangling entrenched opinions and misconceptions, original or modern, from the truth of the available information, but that's a better problem than not having the information at all.
     
    Jimc, May 23, 2016
    #26
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  7. K14

    K14 Member

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    K14, May 23, 2016
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