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Double heading GWR with none GWR and brakes

Discussion in 'Locomotive M.I.C.' started by odc, Oct 12, 2007.

  1. James Green

    James Green New Member

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    If the loco over creates is that bad?
     
  2. baldric

    baldric New Member

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    So long as it can create the same vacuum again then no, assuming it doesn't break something.
     
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  3. James Green

    James Green New Member

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    Thank you for the information. I once saw our resident 56xx 5619 with nearly 30 on the vac gauge!
     
  4. threelinkdave

    threelinkdave Well-Known Member

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    The problem occurs if the leading loco, in charge of the brake, can only release 21in with the towed loco pump trying to maintain 25. So there is a problem with over creating
     
  5. Steve

    Steve Part of the furniture Friend

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    The pepperpot on the lead loco will keep the train pipe to 21". The problem comes if the GWR loco is at the rear of the train.
     
  6. howard

    howard New Member

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    The problem then comes if you are running slowly, so the air pump isn't creating a vacuum, and your boiler pressure has dropped so the ejector can't make that high vacuum. A problem we on the K&ESR sometimes have with Western engines when arriving at Tenterden, having worked hard up the bank and the Fireman has let the fire run down a bit too much.
     
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  7. James Green

    James Green New Member

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    Yeah GWR Ejectors eat steam!
     
  8. bob.meanley

    bob.meanley Member

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    What an interesting thread and quite worrying. It sounds as though there is a distinct lack of maintenance of brake systems in certain quarters. when properly repaired and maintained the GWR vacuum brake is an absolutely superb system with a number of very clever features, but it does need to be maintained. The comments about welsh 56 drivers is pretty superfluous - they got by because the brakes worked, having been maintained by people who actually knew what they were doing. Comments about firemen having to be quick on the hand brake are appalling, if the reservoir side leaks that badly the engine should simply not be in traffic until the leakage is sorted.

    All ejectors use steam, and will use even more if the cones are worn, they do wear out due to erosion of the cones and become inefficient, far too many people seem to believe that they last for ever. The great beauty of the GW ejector is that you do not have to use it once you get moving, our panniers will hold the brake off from below 10 mph. What the GW brake system does require however is that those people who mend the trucks at the back actually pay attention to the vacuum cylinders, pipework and hoses on the coaches behind. The pumps on our engines are perfectly capable of maintaining the 25ins on trains of 10 or 11 coaches with decent brakes and even the 4 inch pump on 9600 will hold the brakes off on 8 coaches. All you have to do is to make sure that the pump pistons and rings, piston rods, glands and valves are in good order, that there is not excessive travel on the valves and that the whole is properly lubricated. 50/50 paraffin is to be preferred, when the LNWR used the GW patent for air pumps, they used paraffin, but it was possibly more oily in those days, but definitely not the cylinder grade oil that I have seen some ignorami using. Paraffin will certainly help to keep the valves clean and free from gumming and sticking for long periods. The VR valve too needs care in maintenance, the top seat can cause leakage and some sheds took the cap off and cleaned them at every washout, putting a little lub oil in the well in the bottom cap to aid lubrication and sealing. We have seen problems with VR valves due to some pretty grotty attempts by other's at new piston rings, causing the pistons to stick.

    The comments made quoting instructions for working with engines with inferior brake systems are spot on, GW on the front (the reason for the arrangement recently with 5043 and 6233) and crack the reservoir release cock to control any over creation of vacuum.

    The moral of all of this is that if you are having trouble with Great Western vacuum brakes, somebody is not maintaining them properly and you need to stop using the engine until it is mended properly, they are after all BRAKES and do have a pretty fundamental function; the old saying "anybody can start an engine - it takes a bit more to stop it" is not helped at all by badly maintained brakes. If the maintenance staff do not know how to mend them properly then they should either be trained, or find someone who can mend them.

    Regards
    Bob
     
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  9. James Green

    James Green New Member

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    Quite right! It's like everything if it is looked after properly then it will work! It saddens me aswell to see that G.W.R brakes are not being maintained properly at my local railway 5619's vacuum pump does not work and it's reservoir leaks off far too quickly this should not happen in practice and I think something should be done right away because a loco need it's brakes!
     
  10. Cosmo Bonsor

    Cosmo Bonsor New Member

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    Thread resurrection....
    +1 to what Bob said.
    I've driven GWR tanks that leak off the chamber side scarily fast.
    Funny that no-one's mentioned Gresham and Craven Dreadnought ejectors.
    There is the main air clack between the the vacuum relief valve and the train pipe.
    This means you can put what vacuum you want in the train pipe and so long as the clack is in good nick the VR valve won't operate.
    Makes double heading with GWR engines really easy.
    You can get 25", you might have to put the handle up for a bit though.
    Dreadnoughts are brilliant things.
    You can service just about any component other than the main steam supply valve with the engine in steam, they are easy and intuitive to use and as long as the small jet is running you maintain your chamber vacuum.
    No running for the handbrake!
    It's not arcane knowledge BTW, it's in the Black Book.
     
  11. burnettsj

    burnettsj New Member

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    I've driven GWR (vacuum brake fitted) tanks where the reservoir hardly leaks and there is no need to use the ejector above 3 MPH - due to the vacuum pump. I'm afraid that is down to poor maintenance rather than a design fault.

    It its that scary - the loco should be stopped!

    Stephen
     
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