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BR Standard class 6 No. 72010 'Hengist' and Clan Discussion Thread

Discussion in 'Steam Traction' started by Bulleid Pacific, Nov 23, 2009.

  1. Jamessquared

    Jamessquared Nat Pres stalwart

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    I'll look next time ... but define "section". Do you mean the gross shape of the spring, or a slice through the material making up the spring? Hence in my images above - are you saying they are trying to make something that looks like the top image, or the bottom one?

    Tom
     
  2. osprey

    osprey Resident of Nat Pres

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    Love the wobbly bit...always made me smile...
     
  3. Dave Williams

    Dave Williams New Member

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    I believe it is called Timms section.
     
  4. northernsteam

    northernsteam Member

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    It's the top one James. Check out the bogie build section of the Hengist/ Clan website.
     
  5. 30854

    30854 Resident of Nat Pres

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    If circumstances permit Tom, please don't forget to grab a few photos. I was also thinking along the lines of the photo you posted.
     
  6. Jamessquared

    Jamessquared Nat Pres stalwart

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    Which is what I thought - hence not understanding @std tank reply saying “no” …

    Tom
     
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  7. std tank

    std tank Part of the furniture

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    The top image is a square section spring. This can still be made and is used in some safety valves. You will see the difference when you look at one of the bogies mentioned. Oh, I forgot to mention Camelot's bogie.
     
  8. std tank

    std tank Part of the furniture

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    The top one is a square section spring. This can still be made and is used in some safety valves.
     
  9. Hermod

    Hermod Member

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    My hero( mr Webb )had driving wheels cast centrifugal in steel.
    These springs will be piece of cake and X ray and ultrasonic control not impossible
     
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  10. RLinkinS

    RLinkinS Member

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    If Mr Webb had been able to cast satisfactory springs in steel he would have done it. The fact that he did not tells us that it cannot be done because the metallurgy of cast steel is not suitable for springs. I am sure he knew that and we should be guided by his example

    Sent from my SM-A105FN using Tapatalk
     
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  11. Cosmo Bonsor

    Cosmo Bonsor Member

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  12. ianh1

    ianh1 Member

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    As you can see from the extract from SL/DE/19544, the bogie side check spring is flat rectangular section

    Bogie Spring.JPG
     
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  13. osprey

    osprey Resident of Nat Pres

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    Very interesting. My gut instinct tells me that this type of spring gives a damping kind of influence that a coil spring would'nt. Correct me if I'm wrong?
     
  14. class8mikado

    class8mikado Part of the furniture

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    Wondered if the flat faces give the spring stability if the compression ' bottoms out' ?
     
  15. Ploughman

    Ploughman Part of the furniture

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    We have this section of steel in our 40t WELTROL bogies.
    2 springs nested and of opposite coiling to each other per wheel set.
    One of the smaller inner nested springs was found to be broken and not economical to renew with square section.
    So, following advice we replaced it with round section.
    Bearing in mind the realistic potential use, speed and amount of movements this wagon is likely to make.
     
  16. ianh1

    ianh1 Member

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    We have got an alternative design of a inner/outer round section spring solution. If we went down that route we would need Vampire testing. The bogie side control springs can be fitted at any time so we're not in a hurry to go down that route and will continue searching for now.

    Osprey - as you can read in our Construction > Bogie section, E.S. Cox concludes by saying that "only a combination of stronger side control springs plus appropriate damping could give the desired result".

    The damping is provided by the Ferobestos pads on the bottom of the bogie bolster cups. These sit on top of grease lubricated brass pads. The original 1951 BR Instruction Manual shows that these pads were grease lubricated
     
  17. 8126

    8126 Member

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    Not really. It still behaves exactly like a conventional round wire coil springs in its basic behaviour. Mostly, it's a way of getting a shorter spring (both free and fully compressed) for a given set of characteristics.

    All coil springs are basically torsion bars wrapped into a helix, so the wire is twisted rather than bent like the leaves of a leaf spring. Round wire is fundamentally the most efficient solid shape for coil springs - you get the highest proportion of the material at your limiting stress and the maximum stiffness for a given material cross section (so you can have less of it). But if you've got a design operating in a fixed envelope, that just needs to be that bit stronger, or that bit stiffer, or that bit shorter, the most efficient spring may not be the best choice. You can make the windings square or rectangular and stiffen them without changing the turn-to-turn pitch, or you can close up the pitch but maintain the same gap between turns.
     
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  18. 30854

    30854 Resident of Nat Pres

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    That sounds ominously like the sort of trade name used for products containing asbestos. Could anyone please clarify?
     
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  19. MellishR

    MellishR Resident of Nat Pres Friend

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    and yet
    Vampire testing would take account of numerous variables and parameters. If everything apart from the spring will be exactly the same as on the original, and the inner and outer springs together would have the same characteristics as the original square-section spring, it's hard to see how the behaviour could be different. Whether the behaviour of the original design was ideal in all respects is different question.
     
  20. 5944

    5944 Resident of Nat Pres

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    No, at least not any more. It's a fibre reinforced resin, used as a frictionless, hard-wearing surface. It's still used quite a bit in the rail industry. The cab front corridor connections on modern units have it, so when they're coupled together the corridors slide rather than bind. Bottom of sliding doors is another location.
     
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