De stressing on steel sleepers

Discussion in 'Infrastructure & Stations' started by kettle8632, 31 Oct 2011.

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  1. kettle8632

    kettle8632 Member

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    Hi guys,

    Here in Tasmania majority of our sleepers are steel, but when it comes to de stressing the rail we have huge problems of curves pulling in winter after been de stressed. Do we (ex pom) stress rail on steel sleepers, or use breather switch's. My old patch, Didcot and Northampton never had steel sleepers.
     
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  3. The Informer

    The Informer Member

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    Unless you have a good thick ballast shoulder, I'd say your pi88ing in the wind!
     
  4. Hydro

    Hydro Established Member

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    Few questions:

    What stress free temperature are you pulling to and what radius are the curves?

    What type of steel sleepers are they, spade or crimp ended?

    It's been a while since I've done any stressing, I'm rustier than some of the rails I've put in the track...
     
  5. The Informer

    The Informer Member

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    And those were my next questions!

    I have a handy application on my phone that works out all the extensions etc.

    Or if you want to bore yourself to death i can send you the Standards Documents that we work to!
     
    Last edited: 31 Oct 2011
  6. Ploughman

    Ploughman Established Member

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    Being pedantic the term is Stressing and not De Stressing.
    That term was very much in mistaken use from the 70s onwards.

    If you pull the rail with any force you are applying stress.

    Which issue of TRK/0011 are you on?
     
  7. Hydro

    Hydro Established Member

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    That always puzzled me, seeing that term. Destressing, well that's easy, I just unkey the rail and cut it straight through :D
     
  8. Trog

    Trog Established Member

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    Yes but the whole idea is to reduce the maximum rail stress by making the stress free temperature more average, hence destressing the rails.

    Also how does your definition fit with natural destressing, where no stress is applied to the rail during the process?
     
  9. Hydro

    Hydro Established Member

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    Just seems to be a change of terminology, that's all. Destressing to me instantly conjures up removing whatever prestress was in the rail to begin with.

    Natural stressing doesn't really, technically, fit in with any definition and seems to me a bit of a misnomer. No stress is applied, the rail is already naturally the right length for the given temperature.
     
  10. Wyvern

    Wyvern Established Member

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    Back on topic. As a know nothing I'm asking whether in this country the places where steel sleepers are used would tend to be jointed rail .? I'm trying to think what it's like at Matlock.
     
  11. Trog

    Trog Established Member

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    No in my experience steel sleepers are usually only used with CWR. The only ones I have ever seen in jointed track were in a siding and had chairs on them marked GWR.
     
  12. kettle8632

    kettle8632 Member

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    I think you might be right.
    --- old post above --- --- new post below ---
    Ok we use 32c as our SFT and some of the curves are <100m radius (very tight)
    The steel sleepers our crimped ended, but we are narrow gauge (1067mm) down here so the sleepers will be lighter also.
    --- old post above --- --- new post below ---
    If you could send it in a PDF that be great


    Oh and by the way. Our rail varies from 63lb to 41kg. (flat bottom)
     
  13. Wyvern

    Wyvern Established Member

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    Dont they have some sort of spike to drive into the ground in this country where track movement is a particular problem?
     
  14. Hydro

    Hydro Established Member

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    I think that's the problem. You've got basically an obsolete style of steel sleeper which has been proven to have poor resistance qualities on very tight curves. The SFT is the same as the UK for crimped steel sleepers.

    Current UK standards for new track have no CWR to be installed on curves of less than 250m radius. For curves of 500m or less, Lateral Resistance Plates must be installed. This of course refers to standard gauge track

    Basically, I'd try increasing the tracks resistance qualities initially. Lateral resistance plates, more ballast, big ass full depth concrete sleepers on the curve.

    I'd consider conversion to jointed track with breathers each side (though you can't effectively manually pack steel sleepers; this may necessitate a change of sleeper type unless you've got Kango hammers and a tamper on call to deal with any joint related geometry problems.).

    It's already proven the rail is wanting to move considerably in the colder months, so if you really anchor the track into the ballast, the rail is still going to want to contract and put itself under a lot of tension, if resistance is sufficient then it may just end up pulling itself apart. I've seen some incorrect overstressed CWR in the winter pull apart and it was so neat you'd think a skilled burner had used a gas axe. Correct stressing and regular ultrasonic inspections for weak points should help mitigate this I'd imagine.

    Just my tuppence worth, I'm not the wisest of birds for PWay engineering but glad to throw something into the ring.
     
  15. The Informer

    The Informer Member

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    Issue TRK3011 Now.
     
  16. relayer

    relayer Member

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    Done miles of stressing on steels.:D Try the vortock rollers it makes life a lot easier. Put the rollers in closer together than the standards state (eg every 10 sleepers instead of 12) Use a rrv to clip unclip or the Cembre machines
     
  17. Trog

    Trog Established Member

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    The above sounds good to me all I might add is how about putting in some adjustment switches every so often but keeping the rail otherwise welded? Not ideal on a tight curve but would at least take the tension out of the rails, while avoiding putting in difficult to maintain joints.
     
  18. kettle8632

    kettle8632 Member

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    They don't use any rollers here. I keep telling them too!!!
     
  19. Trog

    Trog Established Member

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    The test for roller spacing is to walk down the job and kick the rails between the roller positions. The movement or otherwise of the rail, will tell you if it is binding on any of the sleepers between.
     
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