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Proposed New-Builds

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

  1. Tuska

    Tuska New Member

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    Thanks everyone for your links to photos.... So many examples of machines lost...

    Its quite depressing. I love building things. People who love to destroy or scrap what someone else spend years constructing, strikes me as sociopathic in some way. Like a child at the beach who loves to stamp on other's sandcastle constructs and never quite grew out of it.
     
  2. 30854

    30854 Well-Known Member

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    Still attempting to get my head around quite a bit there. Without some handle on how coupled axle loads vary relative to one another (and given that the degree of suspension acting on each is constant) under acceleration, I'm still slightly adrift.

    Regarding Raven's design, the comparatively short con rods, which seem to have worked OK on several designs (the 4-cyl NS class 37's by Beyer Peacock come to mind) as indeed on pretty much every inside cylindered 2-4-0 or 4-4-0 ever built. At the other end of that spectrum, there's a comment (by A.E 'Dusty' Durrant) that longer con rods tend to stabilise large NG locos, this being the reason for the change on BP double-mountain Garratt designs to move the drive from the second to third axle.

    As I'm still struggling with pretty basic CAD packages, the likelihood of me getting any sense from software models of how applied forces affect chassis behaviour is as close to zero as makes no difference!
     
  3. 242A1

    242A1 Active Member

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    In the 1850s the GNR considered driving wheels slightly in excess of 8' in diameter to be necessary for express passenger work. By 1898 6' 8" in diameter came into use. 1934 brought 6' 2" diameter wheels into use for such use on what was now the LNER. Looking elsewhere Golsdorf used driving wheels in excess of 7' in diameter on his 2-6-4.
    Back to the LNER and a design of 1925 fitted with 5' 2" driving wheels was found to be capable of 65mph. By 1941 driving wheels of 5' 10" were deemed suitable for 100mph running in the USA.
    So what was taking place over these 90 or so years? A great deal. Trains were getting heavier and so more powerful engines were required. Greater speed was demandedgnin and this needed improvements in locomotive design. The handling of heavier trains needed more adhesion, more axle loading or if this was unacceptable more driven axles. Improvements in boiler pressure, in valve and valvegear design, in lubrication, the introduction of superheating, refinements in mechanical design; all these and more were stirred into the development mix. But the knowledge of the 1940s that made possible the Class J was not available to those designing in the 1910s and 1920s any more than it was to those designing in the 1850s.
    In the light of the obvious the views of Riddles are, as pretty well always, totally irrelevant and worthless.
     
  4. Hermod

    Hermod New Member

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    Does this mean that LNWR 4-6-0,4cylinder GWR 4-6-0 and LMS Pacifics and all british 4-4-0s were slipping wear machines?I forgot the B12
     
  5. 8126

    8126 Member

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    Yes, I saw that quote when you originally posted it. I just don't quite understand why Riddles, so quick to criticise Gresley for retaining the same wheel diameter as used on his original Pacifics while gradually refining out the detail weaknesses over three succesful classes, didn't see fit to comment on the rather baffling decision of the Stanier team to increase the driving wheel diameter of the Duchesses compared to the Princesses, while they were simultaneously trying to fit the largest boiler possible. He did mention the class in the piece, after all.

    Something to do with blood being thicker than water, perhaps.

    As for your question about my comment on the effect of driving on the leading axle, my example was relative rather than absolute and I had already stated that anything without a trailing truck had an advantage compared to a Pacific. Divided drive is a different case again.
     
  6. Hermod

    Hermod New Member

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    There is a describtion of this retrograde step in Riddles and the 9F - isbn 0711012083 -page 10.
     
  7. Hermod

    Hermod New Member

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    Short rods are not so bad on three cylinder engines.
    Ravens conrods were about same length as many Gresley locomotives like P 1 and 2,minerals etc.
    It is the upward force on slidebars(going forward) that is problematic and gets worser the shorter rods are.
    Im Denmark some two cylinder 4-6-0 with 2.2 m conrods were built 1912
    and some three-cylinder around 1919 with 2.5 m rods.The last to be cut up was Swiss built two cylinder in 1965.
    On a british outside cylinder locomotive there is 6 feet eigth beetween slidebars and 4 feet eigth between rails
    On NG african Garratts this ratio must be much worse and piston forces bigger as well.
     
  8. Lplus

    Lplus Well-Known Member

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    The bogie isn't in the wrong place - it's right there with the rear wheel just in front of the front drivers.....;)
     
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  9. andrewshimmin

    andrewshimmin Active Member

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    Erm, I don't think these lost steam classes were scrapped because someone liked to scrap them. They were scrapped because they were worn out, outmoded, overtaken by the operational requirements, or no longer economic to operate. They were scrapped because they were worthless and no longer had a purpose as locomotives, but their raw materials were valuable.
    It's sad that we didn't end up with a more representative cross-section of steam locos preserved (from different eras, companies and types), but it's almost miraculous how many *did* survive in Britain, given that they were, by the 1950s if not before, completely obsolescent.
     
  10. johnofwessex

    johnofwessex Well-Known Member

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    But in the days of steam, what was the fastest speed needed on most services? I suggest that a large number of locos capable of accelerating quickly to 75mph and maintaining that speed uphill would have made a much greater impact on improving services in the 50's than a smaller number of 'Greyhounds' that could reach 100
     
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  11. ross

    ross New Member

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    Perhaps that was the reasoning behind the standard 5's
     
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  12. LMS2968

    LMS2968 Well-Known Member

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    I believe it was Riddles who suggested the wheel size increase to Stanier, something he later regretted.
     
  13. Hermod

    Hermod New Member

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    from post 1146

    There is a describtion of this retrograde step in Riddles and the 9F - isbn 0711012083 -page 10.
     
  14. S.A.C. Martin

    S.A.C. Martin Well-Known Member

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    Astonishing. No railway in UK benefitted from Pacifics? Well blow me down. I suppose the LNER didn't get any benefit from its Pacifics. Not higher speeds, not non stop runs, speed records, not ridiculous amounts of advertising, not heroically lengthy trains during the second world war. No, no benefits whatsoever.

    o_O
     
  15. S.A.C. Martin

    S.A.C. Martin Well-Known Member

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    I'm not sure there is much justification for that statement by Hermod. It is quite clear that with the best practice of maintenance, lubricants and driving, both Gresley, Raven, Thompson and Peppercorn arrangements of three cylinder engines were all perfectly capable of reliable and high performance work.

    The conjugated gear suffered during the second world due to maintenance issues and the design of the big end and the subsequent wear in the pins associated with this arrangement. Being of a conjugated design was not the direct cause of failures within the conjugated valve gear LNER fleet - reflected in the Stanier/Cox report well.

    The more I look at high mileages for locomotives on the LNER the more I know the story isn't so simple as "high mileage equals reliability". It's a factor, but there were shopping requirements together with carefully timed intervals for repairs. Distances for the work done by different classes to also be considered - which travels further: an A4 regularly running York to Kings Cross on passenger trains or an A2/1 running Peterborough to Kings Cross fast freights the same number of times?

    In short: circumstances dictated railway needs, and there's no straightforward answer. But clearly when looked after correctly, there was nothing particularly wrong with the Gresley arrangement. The Raven arrangement was also fine and in the B16/1s lasted to near the end of steam.
     
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  16. 30854

    30854 Well-Known Member

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    Come now Simon, it's not as if "Hardwicke's" performance didn't tell us nothing bigger than a saturated 2-4-0 was ever going to be needed ...... :Wacky:
     
  17. ross

    ross New Member

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    @Hermod : Can I say, speaking for myself alone, that I find your constant criticism of all the British locomotives tedious and frankly insulting.

    To my eyes most foreign locomotives are strange, unattractive machines. Whatever merit they may have had is in the past, their continued existence now is simply down to their attractiveness and a sense of nostalgia, so I guess someone must like them. I certainly wouldn't have the bad manners to join a french enthusiast site and troll them about how ugly their beloved trains were.

    If you are so averse to British steam locomotives, why do you come to a British railway enthusiast's site at all? To tell us our railways should have been built differently to a different loading gauge so we could have run ugly French 4-8-0's? To tell us that locomotives that were regarded by many as the finest and fastest pacifics ever built should instead have been designed with soup plates for driving wheels? To inform us that we must stop running our beautiful steam locomotives in favour of building stationary boiler houses for bizarre thermos gas-bag power units?

    I presume you are a locomotive enthusiast. You seem well read and knowledgeable, but you make yourself appear foolish by repeating your bizarre claims ad nauseum.
     
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  18. RLinkinS

    RLinkinS New Member

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    If 75 mph was sufficient then the 9f meets the requirement as it stands and there seems no advantage in moving to a 4-8-0. Their performance on the S&D was outstanding. If we were designing for the main line today with the problems with flangeless drivers then the 4-8-0 would be the better option. The use of a narrow firebox allows the use of larger drivers and consequently an increase in maximum speed. I looked at the sectional drawing of Chapelon's 240P and itseemed to offer an elegant balance between the positioning of the coupled axles and the firebox. I envisaged 5' 8" coupled wheels and a firebox similar to that of a King. I am afraid that we are unlikely to see it in full size but someone might be persuaded to build a model in 5" gauge which would be fun. Oh for 30 hours per day and 8 days per week.
     
  19. Hermod

    Hermod New Member

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    Thank You for telling me that I insult British Steam Lovers.
    It has been a mental game for me to see how much steampower can come through a shrinking UK mainline loading gauge and how to run a line like NYMR if open coalfire is prohibited.The Riddles 4-8-0 phantasy based on 9F technology can be seen here

    https://imgur.com/whbIOWW

    and an in side two cylinder compound 2-10-0 here

    https://imgur.com/D5SFiPX

    Again thank You for being angry enough to write.
    I did not see it coming that way.
     
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  20. D6332found

    D6332found New Member

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    VALOUR would be a fine engine, and today we remember her rememebrance. Have set up an appreciation group on Facebook. Time to re-examine their performance and it was a truly special engine. Think Gresley quickly sideline these and Raven's Pacific. The Caprotti version was perhaps a match for an A1 despite the firebox... https://www.facebook.com/groups/186831175208314/
     

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