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Post by District Dave on Sept 21, 2007 7:18:06 GMT
Pat,
I remember years ago you did tell me why the trainstops on the draw up signals at Whitechapel are so slow to go down but I don't remember the whole story!
It's something I'm often asked about - could you remind me of the situation.
Ta
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Deleted
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Post by Deleted on Sept 21, 2007 11:59:55 GMT
Channeling COLIN: whitechapel uses the old form of slugging a trainstop which is controlling the speed by the means before the arm goes down the air has to feel a bit of pipe first then when its full up theres another pressure to release the arm to the lowered or off position 3a) They are normally slowed on purpose. An extra length (or sometimes referred to as a "slug") of air hose is put in to slow the air reaching the trainstop. This means the stop will lower somewhat slower and provide just that extra bit of safeguard, and means you would have to maybe slow to slightly lower than the "booked" speed before the trainstop lowers fully. It takes into account the less-accurate deltas used. Many re-signalled areas have more accurate position detectors installed, and therefore do not require this exta "slack." the trainstops are effectly speed control trainstops which protect the junction in front of the station starters as the points are too close. how they actually work is this instead of additional circuits its simply done by instead of feeding the trainstop directly to the valve like any other signal this is done by feeding another bit of air main pipe then to the trainstop thus taking longer to fill the pipe with air thats why the trainstop lowers very slowly and thats why you get a dual aspect which seems to be forever Hopefully aetearlscourt will explain a bit more  |
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Post by Deleted on Sept 21, 2007 15:01:28 GMT
as theonekea says thats about it really recently we got a job at whitechapel saying they were to slow to clear so that went back as a NCF (no cause found) failure as they are suppose to be slow they are just part of speed control to stop you drivers coming in to the platform too quickly and spad'ing the starter and potentially running into a crossing train but the same applys as anywhere else if the starter is cleared then the trainstop i.e EN100 would also be down and the aspect showing a green
earls court EC280 is automatically selected (no physical lever in IMR) when EC29 is cleared and will show a amber aspect the only time you will see it red is if a train is coming from platform 4 then heading towards west ken but as you approch it it will go down and show a amber this is done when the first platform track is down (train coming in) then a 4 1/2 sec relay is energised this will then release the trainstop to start going down (EC280 also is slugged but you can see the pipe its between the signal and the trainstop)
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