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Post by confusedcom on Apr 1, 2005 20:19:18 GMT
Hi, just wondering how it is that the rails can be +400 and -200 or there abouts? Somone mentioned at potential divider, but how would that work?
Thanks for any info.
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Deleted
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Post by Deleted on Apr 1, 2005 20:44:47 GMT
The God of Railway Knowledge, Clive D. W. Feather, has a diagram of how it works in this Google Groups archived post: tinyurl.com/5ycv6 |
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Post by Admin Team on Apr 3, 2005 16:44:33 GMT
The God of Railway Knowledge, Clive D. W. Feather, has a diagram of how it works in this Google Groups archived post: tinyurl.com/5ycv6On a general point, I'd take a little issue about the 'God of Railway Knowledge'. I agree that he is knowledgeable, but he's not infallible. In the days when I used to contribute to uk.transport.london he replied to a thread about the District, and his answer was wrong. I corrected him, he swore white was black and finally (and not very gracefully) back pedalled and admitted his information 'might be a little out of date'. It was - by about 35 years! So don't assume all you read is 100% accurate and/or up to date. |
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Deleted
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Post by Deleted on Apr 3, 2005 18:30:10 GMT
Really?
It seems to me that most of the stuff he posts is every bit as truthful, well-researched and sensible as anything that may be posted by an actual railway employee. True, I doubt he's infallible, but he certainly knows a hell of a lot about railways.
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Tom
Administrator
Signalfel?
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Post by Tom on Apr 3, 2005 18:36:38 GMT
He may know the principles of something but not the details. That Google Groups Post is an example; he talks about the weak reference to ground when actually each traction current section is tied to earth quite intentionally for traction earth detection equipment.
I remember seeing his writeup of a tour of Wood Lane and he got a lot of signalling details wrong, including claiming a disused blockjoint was still in use for the signalling despite it being a jointless track circuit and the presence of two bonds straight across the joint!
Incidentally, a signalling engineer I used to work with (and will be working with again in a couple of weeks) was very similar. He was ever so slightly embarassed about having to ask me to look for a fuse bay he couldn't find on the drawings. ;D
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Deleted
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Post by Deleted on Apr 3, 2005 22:05:14 GMT
I agree that he is knowledgeable, but he's not infallible. In the days when I used to contribute to uk.transport.london he replied to a thread about the District, and his answer was wrong. I corrected him, he swore white was black and finally (and not very gracefully) back pedalled and admitted his information 'might be a little out of date'. It was - by about 35 years! I couldnt agree more. I know of another instance where he has said the same to an ex victoria Line I/O (who now is at upminster), even thought the IO was correct he swore blind that he was wrong!  |
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Post by third rail on Apr 18, 2005 17:51:36 GMT
what type of third rail system is used for the london underground and hoew it differs from the third rails used in the new york subway and paris metro
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Post by setttt on Apr 18, 2005 17:58:00 GMT
London Underground uses the fourth rail system, whereby trains pick up current through the positive rail, and return it through the negative rail, unlike the more common third rail system, where there is no negative rail, and the current is returned through the wheels of the train.
EDIT: Just to add to that, the Paris metro uses rubber tyres, so the system they use would be very different to that of the tube, as current obviously can't be returned through rubber!
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Post by Dmitri on Apr 19, 2005 6:06:06 GMT
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Post by Nick on Apr 30, 2005 11:52:03 GMT
The Paris Metro is in effect a three-rail system. The cars have vertical and horizontal rubber tyres. The horizontal ones bear against vertical guide bars, which are also the conductor rails. The vertical tyres run on concrete tracks and normally take the weight of the train. However, there are standard steel wheels inside the rubber tyres and steel tracks inside the concrete tracks. These are used at junctions or if a rubber tyre fails, and the cars have collector shoes that bear on the rail to provide current return.
See Brian Hardy's "Paris Metro Handbook" (Capital Transport) for details.
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