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West Somerset Railway General Discussion

Discussion in 'Heritage Railways & Centres in the UK' started by gwr4090, Nov 15, 2007.

  1. buzby2

    buzby2 Well-Known Member

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    That does happen sometimes, however, "Stu in Torbay" said he experienced the problem " ....when there was no pull on the drawbar, i.e. downhill and coasting on the level."
     
  2. Christopher125

    Christopher125 Part of the furniture

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    ahh yes, my apologies, i'd read that in the opposite way.
     
  3. Orion

    Orion Well-Known Member

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    There was a similar issue with the Britannias early in their careers; it was resolved by stronger tender drawbar springs. Might there be a soluton here?

    I must say that I have never had the experience mentioned in this thread with a Churchward/Collett 2-8-0, but I do remember the Hawksworth 15XX on the SVR given a very lively fore-and-aft ride!

    Regards
     
  4. acorb

    acorb Part of the furniture

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    Have experienced this with 5542 on the West Somerset and the Didcot GWR 2-8-0 on the Gloucs Warks. I haven't expereinced this with 4566 however on the SVR & I have ridden behind her being worked very hard!
    As an aside regarding 1501, when she was first restored many thought she would be a proper track basher due to her large cylinders creating a wobble, but this proved not to be the case and she was a very popular and gutsy performer not troubling the p-way dept. That's not to say her riding qualities aren't 'different' to say the least, but that's probably more down to her shorter wheel base creating a bounce. Crews describe her as a 57xx on steroids and she will pull just about anything thrown at her and I for one look forward to her return hopefully next year.
     
  5. aldfort

    aldfort Well-Known Member

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    I was on the footplate of said loco for the morning turn a few days beforehand. As a trainee I do what the fireman tells me and the morning firemen was quite specific in his instructions about how much the coupling was screwed up.

    That said -didn't notice that much lurching on the footplate during the morning, no more than is usual for this loco anyway.
     
  6. chilldude111

    chilldude111 New Member

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    I was the trainee guard on that trip on the 31st i think, but sorry to say guys but it just happens, its a characteristic of 3850. Most people on the railway tell me that it is to do with the small wheels and large amount of power that this loco has. Also it could be because the the coupling was not tight enough!

    Hope that helps

    Chilldude111 (Phill)
     
  7. daveb

    daveb Member

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    If the problem is small wheels and lots of power, I would have expected the problem when working, not, as Stu reported, when running downhill or coasting.

    I can't say that I've noticed it with 3850, but I do recall a similar issue with 5224 when it was visiting the WSR a few years ago. I can't remember whether this was when working or when coasting, though.
     
  8. chilldude111

    chilldude111 New Member

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    Very true. Well i have been told by drivers that it normaly happens between 23-24 MPH. Im sure someone said it was something to do with hammer blow. but i dont know what that means im afraid. As for 5224 it was a bad engine to ride behing when i traveled behind it. It can happen behind lots of locos and i think one of the contributing factors is the tightnes of the coupling.
     
  9. Steve

    Steve Resident of Nat Pres Friend

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    I don't recall 5224 being a significant problem in this respect when it was on the NYMR although it was a non-preferred choice for the diners!. As for slack couplings, one of the more awkward things with a GW vacuum braked (ie non-steam braked) loco is squeezing up and holding it there whilst the coupling is tightened.
     
  10. gwr4090

    gwr4090 Part of the furniture

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    This fore-and-aft shuffling effect is a characteristic of all 2 cylinder engines to some degree. It is a consequence of the fact the the reciprocating motion on a 2 cylinder engine cannot be fully balanced. There has to be a compromise between the residual vertical motion which leads to track hammerblow, and horizontal motion which is uncomfortable for passengers. Different loco deigns have different solutions. GW freight engines are generally balanced for low track hammerblow. The horizontal motion becomes particularly noticeable when the frequency hits a mechanical resonace of the buffer/drawgear system. Unfortunately this occurs at about 25 mph for some classes including the 28xx. It can be nullified to some degree by adjustment to buffer/drawgear tension and position of reversing gear especially when coasting. But I gather it is not particularly noticeable on the footplate itself, so the crew may not know what is happening to the passengers ! I remember that the BR Britannias were rather bad in this respect when new, but I guess the wheel balancing was later modified. The GWR Hawksworth Counties were also good at "jiggling" the passengers at certain critical speeds but this was greatly reduced by adjusting the buffer tension between loco and tender. Incidentally it is not really a problem on 3 and particularly 4 cylinder engines, as the motion is inherently well balanced and the dynamic forces are much lower..

    PS Track hammerblow is the variable load the wheel exerts on the track. During one wheel revolution the load oscillates around the average (static) axle load. In very extreme cases the axle loading may double at one part of the rotation cycle, and fall to zero at another . Stanier did some experimentas on a Black Five which showed that with incorrect wheel balancing, the wheel could actually lift off the track once per revolution with risk of a derailment occurring. Track hammerblow is also not good for bridges and similar structures, so many designers deliberately opted for low track hammerblow at the expense of passenger (or freight) comfort !

    David
     
  11. chilldude111

    chilldude111 New Member

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    Thanks for explaing that. Makes more sence now!
    thank you

    Chilldude111(Phill)
     
  12. 1472

    1472 Well-Known Member

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    Absolute nonsense (unless your vacuum brake has not been maintained in serviceable condition).
     
  13. aldfort

    aldfort Well-Known Member

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    OK - I have spoken to several train crews now and, as has been mentioned this loco is known for it's tendancy to make the stock surge. I'll pay more attention next time I'm on the footplate. or when riding behind it on the cushions and try to report back.

    On the subject od squeezing up. It's a bit of an art form to squeeze up just the right amount. With most loco's you have to get the brake in at just the right moment or you bounce off. If you squeeze up too tight then it is possible to overtigten the screw coupling and not have any give left in the buffers when the brake is released. So Steve is not wrong and not talking nonsense.
     
  14. gwr4090

    gwr4090 Part of the furniture

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    I travelled on a packed 10-coach train behind 3850 yesterday. There was no surging at all in the first coach even when coasting downhill, so it IS possible to eliminate the effect. The driver was using 45% cutoff when coasting, maybe this is the key ?

    David
     
  15. 1472

    1472 Well-Known Member

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    There is no issue with easing up. If the regulator is opened sufficiently, the buffers compressed, brake applied, regulator closed it goes just fine & there is no bouncing off.
    This applies whether the loco is steam or vacuum braked and assumes that the brake is in proper servicable condition & is being used competently.
    A competent fully trained fireman will know that screw couplings are not tightened to their full extent but screwed up until a set number of threads are still showing (usual minimum of 2; possibly more on tightly curved lines).
     
  16. Steve

    Steve Resident of Nat Pres Friend

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    I didn't intend opening up a can of worms with the subject of squeezing up! All I said, or intended to say, was that attaching a vacuum braked loco to a train is a more skilled task than with a steam braked loco. With a steam braked loco it is dead easy to come up to the stock (stopping 2 metres away, if your rulebook requires that) and then to put the steam brake on as the buffers kiss and squeeze, all in one move. No squeezing necessary. It is virtually impossible to do this with a vac braked loco and stopping without bouncing back slightly is a much harder task. When this happens, as it always does, you have to squeeze, exactly as you described. And GW vac brakes are notorious for leaking off in a fairly short time, however well maintained the loco is.
     
  17. 1472

    1472 Well-Known Member

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    Notorious ?? - maybe so in the Leeds area but not in areas where GW locos are more common - we have one where the reservoir vacuum stays up overnight. There are leakage limits specified in MT 276 for both train pipe and reservoir. Anybody operating a loco which has brakes which don't conform to these limits would find their maintenance policy open to question in the event of an incident.
     
  18. A new lead has been installed at the WSR/NR boundary at Norton Fitzwarren. It will give direct access to trains from NR onto the former Barnstaple branch when tracklaying is completed on that formation. The Norton Triangle (outer and inner) is planned for completion in the new year. Pictures of the installation of the new junction are at http://www.wsr.org.uk/cgi-bin/gallery.cgi?h=Barnstaple Junction&t=bjpix also see brief news item at www.wsr.org.uk and a fuller report at http://www.wsra.org.uk

    Steve
    (WSW)
     
  19. Stu in Torbay

    Stu in Torbay Part of the furniture

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    Saw the ultrasonic train with Class 31 on in the bay at Taunton, and glimpsed the new lead as I passed en-route to Newton Abbot yesterday
     
  20. gwr4090

    gwr4090 Part of the furniture

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    Quite a busy day on the WSR on Wednesday, with over 2,300 passengers - possibly a record for on an ordinary (non gala) day ? Every one of the 29 available coaches was pressed into use. Trains were full and standing, with extra services laid on at short notice. Minehead station entrance gates had to be closed for a while due to overcrowding on the platform. The big attraction was the Red Arrows and Red Devils displays at Minehead. A lot of people chose to travel there by train rather than the congested roads.

    David


    David
     

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