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Current and Proposed New-Builds

Discussion in 'Steam Traction' started by aron33, Aug 15, 2017.

  1. Allegheny

    Allegheny Member

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    Are these the peak values achieved just after the exhaust valve opens, or the mean values? I am thinking that quite a lot of locomotives would momentarily achieve the critical pressure at the blastpipe when working hard, just after the valve opens.
     
  2. 240P15

    240P15 Well-Known Member

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    As said before, I`m so thankfully that the A1 Trust abandoned Porta`s fantasy A1 and build a traditional British steam locomotive which ,probably, the most of us want to see :)

    Knut
     
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  3. class8mikado

    class8mikado Part of the furniture

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    Agreed. But that is not to say that there is no place for ' evolved steam' as I like to call it. Many of Portas innovations were driven by difficult fuel. Its widely thought that the quality of coal we can get for steam maybe much harder to obtain or even prohibited in the future. If we end up on coaldust/ biofuel hybrid briquettes its good to know that there is some technology that could make that alternative viable.
     
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  4. JJG Koopmans

    JJG Koopmans Member

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    As far as I remember from my calculations, mean values. Critical pressure may occur on valve opening, but before it reaches the orifice it is gone. Please keep in mind that all those preaching critical pressures
    fail to prove it by not showing measurements.
    Kind regards
    Jos
     
  5. Allegheny

    Allegheny Member

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    I understand that attempts are being made to carry out some of these measurements using a high speed data logger, but it is proving difficult to organise.

    Going to the discussion on saturated vs superheated steam, I am thinking that compounds were more common in the 19th century, and declined when superheated steam became more popular, although obviously some superheated compounds were built.

    My thinking is that the advantages of compounding applied more to saturated than to superheated steam,- I'm not sure whether this is correct.

    Therefore, should our hypothetical new build saturated locomotive for a heritage railway be a compound?
     
  6. class8mikado

    class8mikado Part of the furniture

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    Tricky one, better ask Hermod.
     
  7. 240P15

    240P15 Well-Known Member

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    Absolutely. As long the new technology doesn`t affect the eaesthetic of the locomotive and remove all steam coming out the the chimney I`m nothing against it:) Steam locomotives fired with wood isn`t something new.

    King class no. 6023 as mentioned modified by Jos Koopmans is a good example when new improvement doesn`t affect the appearance. But a "King"class with a Giesl and GPCS on the other hand....:eek:

    Knut:)
     
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  8. 30854

    30854 Resident of Nat Pres

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    My own feeling is that UK designers never really put the same sort of effort into developing compounding as those in France. Perhaps it's more a comment on UK loading gauge than owt else, as the Midland's Smith/Deeley design worked well enough, unless overloaded (which in any case was zilch to do with the flavour of their expansion cycle), as did Bowman Malcolm's 3ft gauge vonBorries 2-4-2T (one of which really should have been preserved ..... bloody UTA!), which both preceeded and outlived the better known Midland class.

    Whilst incorporating a few 'tweaks' can be regarded as sensible enough, fullest 'Porta-isation' of an existing design can surely only be taken so far before the whole exercise becomes pointless, but count me among those who'd love to see a novel design incorporating a lot more up to date thinking. Somehow, I suspect it ain't about to happen for any number of reasons .... not least of which is just why such a machine might be needed.
     
  9. Hermod

    Hermod Member

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    I do not know,and I doubt anybody else can say for sure either.
    But it can be measured maybe.
    The great steam locomotive devellopment failure was the stationary test plants.
    A complete locomotive on rollers are not telling the true value of a locomotive on rail-duty.
    In Germany and France they fell in disregard before WW2 and mr Ell in UK did not rate them high either.
    It was more fun to try on rails.
    What could have been done stationary was to measure the cylinder and crankshaft perfomance alone from a stationary boiler where steam conditions could be varied and controlled.
    There is no car develloped today where engine performance has not been measured accurately on a test bench.Temperature ,air density, humidity ,fuel,moon phase etc.
    If that had been done for locomotive cylinders and valves, Chapelon would not have been a Hero Saint.
    Mr Diamond of LMS pointed out in 1925 from simple indicator diagrams that a 4-4-0 Compound used one third of the steam energy to get steam in and out when going 60mph.
    The mind boggles when mr Cox stated that the Compounds were approx 20% more efficient than other LMS locos he tested on the road in the late twenties.
    What present steam lovers can do is to get some cylinders from linear scrap yards and combine them in different configurations.
    When ,as I think ,the two cylinder saturated ,boiler water heated compound cylinder set proves winner,it is no big deal to rebuild a outside cylinder 0-6-0 tank.
     
  10. MellishR

    MellishR Resident of Nat Pres Friend

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    And me.
     
  11. Allegheny

    Allegheny Member

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    We could start a facebook group, but we'll never decide what colour it's going to be.:)
     
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  12. Jamessquared

    Jamessquared Nat Pres stalwart

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    You mean you can get Facebook in other colours than blue and white? :confused:

    Tom
     
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  13. 30854

    30854 Resident of Nat Pres

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    ...... and set up the whole lot on an earthquake simulator to replicate running at line speed. :D
     
  14. Hermod

    Hermod Member

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    Very good subject for first experiment:

    DOES VIBRATION INFLUENCE STEAM CYLINDER PERFORMANCE?

    Has never been tested I guess

    To prove the verdict this locomotive can easily be modified cylinder vise

    http://www.h0-87.dk/Billeder/Forbillede/F_657_Odense_1971-509-dm0505.jpg
     
    Last edited: Apr 13, 2018
  15. johnofwessex

    johnofwessex Resident of Nat Pres

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    'Locomotive' type boilers were used in the early destroyers, frequently with unsatisfactory results. One contemporary writer suggested that the absence of the vibration found on a locomotive may have adversely affected their performance
     
  16. JayDee

    JayDee Member

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    You can now choose the colour of your messages in the messenger windows with individual friends.
     
  17. Hermod

    Hermod Member

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    Bad engineering probably.The LMS turbomotive had even exhaust flow and low vibration level and was a good locomotive
     
  18. MarkinDurham

    MarkinDurham Well-Known Member

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    Another point about running on rollers - 2001 had lubrication issues with her main bearings whilst at Vitry. It is believed that this was because the running was so smooth, this caused problems with the hydrodynamic wedge which builds up at the journal-bearing interface whilst the axle is rotating.
     
  19. paullad1984

    paullad1984 Member

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    Locomotive boilers don't like continually rolling etc. Besides water tube boilers are more efficient
     
  20. LesterBrown

    LesterBrown Member

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    I believe the torpedo boat destroyers referred to used fire tube boilers with circular marine fire boxes (a bit like Bagnall used on locos like Charles Wytock) arranged end to end, not unusual at that time. Presumably the hulls weren't deep enough for Scotch boilers. In trials the newly introduced water tube boilers were far superior.
     

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