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Guard's handbrake query?

Discussie in 'Heritage Railways & Centres in the UK' gestart door Axe, 9 okt 2011.

  1. Axe

    Axe Member

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    Remembering a comment on this forum from 2 or 3 years ago, I believe there is at least one heritage railway that has modified a handbrake which when screwed down opens a valve to destroy the vacuum of an automatic brake.

    I need to identify any UK heritage railways that have done this. Does your railway meet this criteria please?

    Chris
     
    Axe, 9 okt 2011
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  2. natdawson

    natdawson New Member

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    The NNR has a dump valve fitted to some of their MK1 brake vehicles and the LNER pigeon van as well I think.
    From what I can remember if the handbrake had more than a couple of turns from the off position then the valve would be open and a vacuum couldn't be create.
    The valves themselves were originally from a 47.

    If you need them PM me for contact details.
     
    natdawson, 10 okt 2011
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  3. Martin Perry

    Martin Perry Nat Pres stalwart Staff Member Moderator Friend

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    So if a vac rake is parked on a gradient you have to take the handbrake off before you can create vac ... unlikely to cause major problems as you would be coupled to the loco but might snatch the coupling a bit? I guess this is outweighed by the fact that a train cannot be moved (in vac brake mode) with the handbrake on.
     
    Martin Perry, 10 okt 2011
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  4. paulhitch

    paulhitch Guest

    Welshpool and Llanfair does and I understand the Ffestiniog does also.
     
    paulhitch, 10 okt 2011
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  5. 1472

    1472 Well-Known Member

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    Most SVR passenger brake vehicles have been fitted with a valve operated by the guards handbrake which, when applied, prevents train pipe vacuum being created above 15".

    The objective of this is to alert drivers to the fact that a handbrake remains applied preventing movement & in particular avoiding the risk of wheel flats on brake vehicles where the handbrake has not been properly released.

    Slang term for this item amongst staff is the "idiot valve"!
     
    1472, 10 okt 2011
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  6. Bean-counter

    Bean-counter Part of the furniture

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    The NYMR have an SVR style device fitted to the GW Saloon 80974. It has the same effect as if the communication cord had been pulled - unable to achieve more than about 14" of vacuum. Hence, the loco can attach to the set and start creating vacuum with the hand brake on but can't obtain full vacuum until it is removed. No safety issue as the hand brake is only wound off after the loco is attached.

    Steven
     
    Bean-counter, 10 okt 2011
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  7. laplace

    laplace New Member

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    None of the lines I've worked on have these, but they all run short sets, where one handbrake is enough extra drag to be obvious to the driver.
    If it has slack in it, it's going to snatch whichever brake you take off last.
     
    laplace, 11 okt 2011
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  8. natdawson

    natdawson New Member

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    I think half the reason the NNR system doesn't allow any vacuum to be created is that with a bigger diesel such as a 37 or large steam loco such as the WD the set could still be dragged along with the handbrake partially applied or stock with dragging brakes.

    Before splitting the loco from the stock the handbrake is applied as are the train brakes, the stations are pretty much on the level as well.
     
    natdawson, 11 okt 2011
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  9. Martin Perry

    Martin Perry Nat Pres stalwart Staff Member Moderator Friend

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    Not if you create with the handbrake on, then destroy the vac to do a vac test before you move off. A moot point anyway.
     
    Martin Perry, 11 okt 2011
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