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Inside valve gear

Discussion in 'Locomotive M.I.C.' started by MellishR, Oct 21, 2016.

  1. MellishR

    MellishR Part of the furniture Friend

    Apr 16, 2009
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    And yet many Gresley designs have outside valve gear driving the inside valve, and that can be set up to work satisfactorily.
  2. Jimc

    Jimc Well-Known Member

    Sep 8, 2005
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    SE England
    Heritage Railway Volunteer:
    No I do not currently volunteer
    Gresley was prepared to accept a degree of inaccuracy with the inside cylinder valve events which Churchward and Collett were not. In the same way when Holcroft designed conjugated gear for the first Maunsell southern 3 cylinder locomotives he arranged the conjugated gear so that it bypassed the valve rod expansion, but for whatever reasons it wasn't repeated and the Southern engines ended up with 3 sets of gear. Its all about the specific compromises each each CME is prepared to accept in different areas of the design.

    There's a sentence in Cook's Swindon steam "GW locomotives had extreme regularity in their exhaust beats, and we certainly could not permit of anything like two beats and a woofle which was noticeable on some rival lines." I do believe such an exhaust from a particular rival line (not the LNER) is audible to this day!

    I'm not sure many (?any) of us are really in a place to say definitively which compromises were right and wrong, but we can be aware that such tradeoffs existed right through the designs. We enthusiasts have a habit of picking and choosing certain - usually externally visible - design factors as being vital and ignoring other less exciting factors, but we should at least be aware its a lot more complicated than that.
    Last edited: Nov 12, 2017 at 10:26 AM
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  3. Hirn

    Hirn New Member

    Aug 11, 2015
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    The 15xx was intended for Newport Docks, unfortunately it turned out to be too wide to be usable there, so they ended up
    the Eastern end of the GWR main line.

    ( Presumably they were inspired by the WWII U S military shunters and interestingly the Southern before it brought some of these
    did produce an outline design to build their own version of something like them. )

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