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Post by cudsn15 on Dec 5, 2019 20:11:28 GMT
Are there any leaves left on the trees now? It's December!
oh and every Piccadilly line train I've been on this week has been filthy - both out and in. Is no-one managing the cleaning of this fleet?
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Post by goldenarrow on Dec 5, 2019 20:23:17 GMT
cudsn15 , You'd be surprised how much leafy matter gets blown over onto large land footprints such as railways. We have a significant leaf clearing operation at Heathrow, a concrete monolith yes, but not immune from leaves. Even with the leaves that have already fallen by the wayside, it doesn't take much uplift force for those leaves to be turned into a compostable paste and that is not the kind of track adhesion conditions you want trains with no anti-lock brakes running over.
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Post by tjw on Dec 5, 2019 23:10:06 GMT
Even with the leaves that have already fallen by the wayside, it doesn't take much uplift force for those leaves to be turned into a compostable paste and that is not the kind of track adhesion conditions you want trains with no anti-lock brakes running over. I have never driven a locomotive, but while gravity shunting we would wind on the brake, until you can feel the brake blocks rubbing along the wheel, this cleans off any rubbish, you can then wind the brake on hard to stop. Or less hard if you want to check the speed and stop a bit further along the line.
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Chris M
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Post by Chris M on Dec 6, 2019 0:12:13 GMT
Breaks on modern rolling stock act on the hub or axle rather than the wheel tread, so there are no brake blocks to clean off any rubbish
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Post by goldenarrow on Dec 6, 2019 0:15:00 GMT
Even with the leaves that have already fallen by the wayside, it doesn't take much uplift force for those leaves to be turned into a compostable paste and that is not the kind of track adhesion conditions you want trains with no anti-lock brakes running over. I have never driven a locomotive, but while gravity shunting we would wind on the brake, until you can feel the brake blocks rubbing along the wheel, this cleans off any rubbish, you can then wind the brake on hard to stop. Or less hard if you want to check the speed and stop a bit further along the line. I haven't seen how a 73 stock behaves in poor adhesion from a driving technique perspective so can't comment on that. I think the current situation is born out of a combination of the age of the fleet and the more frequent sharp seasonal changes that are making leaf fall/gusty/damp periods more sporadic and intense.
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rincew1nd
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Post by rincew1nd on Dec 6, 2019 7:08:09 GMT
Even with the leaves that have already fallen by the wayside, it doesn't take much uplift force for those leaves to be turned into a compostable paste and that is not the kind of track adhesion conditions you want trains with no anti-lock brakes running over. I have never driven a locomotive, but while gravity shunting we would wind on the brake, until you can feel the brake blocks rubbing along the wheel, this cleans off any rubbish, you can then wind the brake on hard to stop. Or less hard if you want to check the speed and stop a bit further along the line. Fine for tread brakes, but doesn't work with other types. IIRC the cl158 on the big railway suffered dreadfully when new, such that mixed sets were formed with a cl156 as the cl156 has tread brakes and the cl158 do not.
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Post by tjw on Dec 6, 2019 9:05:53 GMT
Breaks on modern rolling stock act on the hub or axle rather than the wheel tread, so there are no brake blocks to clean off any rubbish I would say that is a design defect... I do know that the braking profile for traditional brake blocks means they become inefficient at higher speeds, c.90 m.p.h. Disk brakes are more efficient at those higher speeds. I have not seen a table for regenerative braking.
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Post by underover on Dec 6, 2019 12:25:24 GMT
Even with the leaves that have already fallen by the wayside, it doesn't take much uplift force for those leaves to be turned into a compostable paste and that is not the kind of track adhesion conditions you want trains with no anti-lock brakes running over. I have never driven a locomotive, but while gravity shunting we would wind on the brake, until you can feel the brake blocks rubbing along the wheel, this cleans off any rubbish, you can then wind the brake on hard to stop. Or less hard if you want to check the speed and stop a bit further along the line. Its not so much the rubbish on the wheels, its the rubbish on the track that is the issue. You can keep the wheel as clean as you like, but you are still on top of track which is slippy. As soon as you apply the brakes slightly too hard, you can lock the wheel set. If you start braking, and you lock, you release the brakes and try again but this all eats into the distance you have before you need to stop until you eventually either spad or come to a stop.
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Post by goldenarrow on Dec 6, 2019 15:28:08 GMT
Normal through service restored for the evening peak. Conditions have been better than originally forecast.
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