Chris M
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Post by Chris M on Jan 17, 2011 19:22:23 GMT
While waiting at Debden yesterday, I observed attachments to the current rails (negative and positive) pictured below.   (click for larger versions) They are apparently insulated from the current, and just lying on the sleepers, not attached or anchored in any way. What are they and what is the purpose of them? |
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Deleted
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Post by Deleted on Jan 17, 2011 19:35:05 GMT
I would imagine they are actually attached as their purpose is to help prevent movement of the current rail.
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rincew1nd
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Post by rincew1nd on Jan 17, 2011 20:36:58 GMT
Earl's Court has similar things, I assumed (as Charlie J states) that they are to prevent rail-creep during the acceleration and deceleration that occurs in stations.
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Chris M
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Post by Chris M on Jan 17, 2011 21:48:15 GMT
That was my thought, and I looked closely at several and couldn't see any way they were attached. The obvious ways would be for them to be L-shaped and stick into the ballast/abut the sleepers or to be bolted to the sleepers. Neither appear to be the case.
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Deleted
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Post by Deleted on Jan 17, 2011 22:14:11 GMT
I would imagine this shape provides more restraint on less stress (leverage!) and easier insulation.
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metman
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Post by metman on Jan 17, 2011 22:21:25 GMT
They are screwed to the holes in the sleepers. I too thought they were to stop the creep of the conductor rail either from train shoes or thermal movement.
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Post by railtechnician on Jan 18, 2011 3:51:56 GMT
They are current rail anchors and are bolted to the sleepers through the angle section. It is not only current rails that have anchors, you'll find them in pointwork too, to prevent lead and lag occurring in switch rails which could cause point failure. However, point anchors are a different animal and secure the fixed rails at the heel ends of the turnout switches to the adjacent main running rails.
On the point of rail creep temperature does of course play a part in both current rails and running rails, current rails simply sit in the pots and thus have to be anchored elsewhere, every so often bridged and unbridged current rail gaps allow for thermal changes. For the running rails there are overlapping rail expansion joints which allow rails to slide to expand and contract lengthways.
Sticking with temperature, expansion and contraction is also allowed for in the air main GI pipe, which runs throughout the cable runs on most lines, compensators were/are fitted seven to the mile (IIRC) in open sections and are also found in tunnels though the temperature changes are much smaller.
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