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Instanter couplings

Discussion in 'Railway Operations M.I.C' started by Eightpot, Jun 4, 2012.

  1. Eightpot

    Eightpot Part of the furniture

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    Is there any reason as to why these couplings cannot be used on or with passenger carrying rolling stock?
     
  2. Steve

    Steve Resident of Nat Pres Friend

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    I don't think that there is any specific regulation that prohibits Instanters, three links or Kuplex from being used. At the end of the day it needs to be fit for purpose and if an Instanter fits that bill, then it is OK.
    Having said that, it runs in my memory that dumb buffers weren't allowed on passenger trains so it might just have been the case with link couplings. Probably in some long gone HMRI requirements for passenger trains that no longer applies.
     
  3. NNR Engineer

    NNR Engineer New Member

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    The simple reason is for corridor connections, and the buckeye needs to be used for this. In the event of the buckeye failing then the emergency screw-link coupling would be used, because the corridor connections would still be able to be used as the Guard must have access to all parts of the train where a corridor connection is used. (For example if a fire broke out in one of the coaches)
     
  4. guard_jamie

    guard_jamie Part of the furniture

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    What about carriages that don't have corridor connections, NNR engineer? Or those that do but use screw link? The LMS and GWR never quite got there. I think that there is more to it than that.
     
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  5. NNR Engineer

    NNR Engineer New Member

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    Like i said "When corridor connections are used" for example on BR suburban coaches there aren't any corridors from one end of the coach to another. Rules and regs state that when possible the buckeye must always be used.
     
  6. guard_jamie

    guard_jamie Part of the furniture

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    Sorry to sound petulant, but you didn't say that, have a read of your post again. I take your point though, they are the safer option and must be used if possible.
     
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  7. The Saggin' Dragon

    The Saggin' Dragon Resident of Nat Pres Staff Member Moderator Friend

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    I thought that if an emergency coupling was used to replace a buckeye, then the corridor connection was supposed to be locked out of use? I would imagine that the use of instanters on passenger stock is not a great idea as they still give a certain amount of slack and could provide quite a lively jolt when the train started moving.
     
  8. NNR Engineer

    NNR Engineer New Member

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    guard_jamie Not wanting to sound rude but I think you should read my first post again! It does say "where a corridor connection is used"

    The Saggin' Dragon - You are certainly correct about the jolting, also with the corridor connections in place, I'd lile to see someone attempt to get the instanta into the short position! However if the the emergency screw coupling is used the coach doesn't need to be locked out as again the Guard doesn't have access to all of the train, for example if there was a fire at his coach and an intermediate part of the train was locked out then how would he/she get all of the passengers off quickly and safely?

    Hope this answers your question(s)
     
  9. guard_jamie

    guard_jamie Part of the furniture

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    This is getting ridiculous so this will be my last post and I apologise for getting my handbag out, but NNR Engineer, you only say 'where a corridor connection is used' in relation to the guard needing to access all part of the trains. The beginning of the post, the first sentence, reads like you are saying Instanters cannot be used with passenger stock simply because of corridor connections, when of course we are both aware that many trains on heritage railways do not have such.

    So there is clearly more to the ban on Instanters on passenger trains than corridor connections.
     
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  10. NNR Engineer

    NNR Engineer New Member

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    Sorry guard_jamie I mis-interpreted your post! There are obvioisly more reasons such as heavy jerking.
     
  11. John Webb

    John Webb Member

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    It would seem from the "Oxford Companion to British Railways History" that the GWR first introduced the instanter form of three-link coupling to reduced the slack between goods wagons. The use of the screw-coupling on passenger vehicles is to bring the buffers into contact with each other to eliminate snatching or 'surging'. But it then becomes difficult to push such a train at any speed. The central 'buck-eye' coupling does away with buffer contact altogether and allows high-speed propelling movements without risk.

    Regards,
    John Webb
     
  12. Steve

    Steve Resident of Nat Pres Friend

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    Not sure that you're right with this but happy to be told I'm wrong. If you use an emergency screw coupling in lieu of an Alliance (buckeye) coupler, you have to have the coach buffers extended and this will mean that the corridor connections won't meet properly so need to be closed off.
     
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  13. NNR Engineer

    NNR Engineer New Member

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    I've looked further into this, and I seem to have found a definitive answer to the original question. - The overall reason for this was that is was the law (and thus also entered into rules and regs) that instanter couplings MUST NOT be used on passenger trains.

    With regard to 'Steve's point here is some food for thought - if you think about the BR Class 101 DMU, they didn't have buffers (so couldn't possibly extend) but were coupled together using a screw-link coupling, and they still had corridor connectors, and these weren't closed off. Hope this helps.
     
  14. Jamessquared

    Jamessquared Resident of Nat Pres

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    This post seems to imply that buckeyes are a necessary pre-requisite of using corridor connections. But that is nonsense; only the SR, LNER, Pullman and (later) BR Mk1s used buckeyes. So there are plenty of GW and LMS coaches perfectly happily going up and down preserved railways with screw link couplings and corridor connections.

    For coaches that have buckeyes, if the buckeye fails and the emergency screw link coupling has to be used, then the corridor connection should be locked out of use. However, that is to stop the regular flow of passengers between the two coaches affected while on the move. It doesn't prevent the guard moving between them, nor indeed passengers in an emergency, since the guard has a key and can unlock the doors if required!

    Tom
     
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  15. Jamessquared

    Jamessquared Resident of Nat Pres

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    I don't think this is true. Saying that the coach buffers are "extended" is kind of a misnomer (though one in common use); it is better to say that when the buckeye coupling is used, the coach buffers are "retracted". AFAIK, the intra-coach distance doesn't change whether buckeyes or screw links are used. So the corridor connections will still meet in the middle.

    Tom
     
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  16. NNR Engineer

    NNR Engineer New Member

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    Jamessquared - Apologies for the confusion, now you have said that and I have read it back, I can see what you mean. What I meant to say was "and the buckeye (when fitted) needs to be used..." It obviously can't be used when there isn't one! You also raise an interesting point about the buckeye failing and having to use the Emergency screw coupling to stop passengers moving between the two coaches whilst on the move, yet you have said about buckeye's not being compulsive for corridor connections, so my question to you is "Why lock out coaches when using an emergency screw coupling, but not when using an ordinary screw coupling? Surely they are the same except one is painted red?"
     
  17. Jamessquared

    Jamessquared Resident of Nat Pres

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    They are not the same, in that a "conventional" screwlink is securely and permanently threaded through one drawhook, and hooked over the second; whereas an "emergency" screwlink is hooked over both drawhooks. Also I think (but haven't studied closely, so might be wrong) that an emergency screwlink is made of slightly thinner material. This makes it lighter, to facilitate being lifted out of a brake compartment and down to track level, but obviously means it isn't quite as strong or rigid.

    Tom
     
  18. Steve B

    Steve B Active Member

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    Am I right in thinking that the corridor connections used on non-buckeye fitted stock are different to those on buckeye fitted ones? I believe that the corridor connection itself forms part of the buffing gear when a buckeye is being used. The non-buckeye coaches (such as some DMUs which did have buffers and screw couplings) had corridor connections that I think had to be physically connected (or have I just imagined that? - I haven't seen one for a while)

    Steve B
     
  19. rule55

    rule55 Member

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    Emergency screw couplings are not lighter than any other - believe me, I lug the things around on a regular basis! They are used daily in exactly the same situations as would be a screw coupling fitted to a drawhook. Class 67s, for example, require an emergency screw coupling in order to couple to coaching stock. Buckeye-fitted stock use Pullman gangways, former GW and LMS coaches fitted with screw link couplings were fitted with British Standard gangway connections. In order to couple one to the other an adapter had to be fitted. When Mk1/2/3 coaches are coupled together with an emergency screw coupling (for example, when it is not possible to couple using the buckeyes), as has been pointed out already, the gangway doors are locked out of public use.
     
  20. NNR Engineer

    NNR Engineer New Member

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    Thanks for clearing that up rule55 and Jamessquared.
     

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