Deleted
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Post by Deleted on Dec 20, 2008 23:15:31 GMT
 Please take a look at the above photo. The white lamp to the right of the NQ17 plate. What is its function? I noticed it was displaying a white light for about 15 seconds as a train was arriving into Finchley Central. The signal was still displaying a red aspect at the time. Can any of the LUL experts explain it to me please because it has me stumped. Thanks in advance. Irishunderground. |
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Colin
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Post by Colin on Dec 20, 2008 23:46:13 GMT
It's a part of the trip cock tester set up.
It will illuminate as the train enters the platform; there will be a ramp further down the platform on the right hand side of the track in the direction of travel which the leading trip arm on the train passes over; providing everything is ok, the light will go out indicating to the driver that the train has passed it's test.
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Deleted
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Post by Deleted on Dec 21, 2008 10:36:23 GMT
Thanks Colin.
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Post by tubeprune on Dec 21, 2008 10:40:41 GMT
Whilst looking up something else the other day, I discovered that the District had its first tripcock testers installed at Embankment both roads on 12th June 1916. Before that, they used to trip trains in service to test the tripcock. Quite how or where they did this isn't described.
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Post by railtechnician on Dec 21, 2008 11:57:33 GMT
It is interesting to note that the questioner clearly asked about the 'white' light emitted from the tripcock tester lens which appears to be blue! This thread might perhaps be linked to the recent one in the District line forum on the same subject referencing white, blue and purple lenses to a 'lunar' white aspect. I think it demonstrates the assertion that the aspect is lunar white despite the colour of the lens.
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Post by happybunny on Dec 21, 2008 16:27:31 GMT
Some of the tripcock tester lights are very dim! I would like to think I would notice if one ever stayed on, but somewhere like Barons Ct or Upney, I'm not so sure !
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Deleted
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Post by Deleted on Dec 21, 2008 16:31:34 GMT
It was white!  But this has got me thinking. How does a tripcock tester actually work without setting off the tripcock? |
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metman
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Post by metman on Dec 21, 2008 19:03:43 GMT
There is a gauge on a ramp, bit like a set of rugby posts that the tripcock has to pass, and then repress a damp for the light to go out. I'm sure there is a photo somewhere. The tester is activated by a track circuit I think.
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Post by railtechnician on Dec 21, 2008 23:43:18 GMT
There is a gauge on a ramp, bit like a set of rugby posts that the tripcock has to pass, and then repress a damp for the light to go out. I'm sure there is a photo somewhere. The tester is activated by a track circuit I think. Being pedantic that is of course 'depress a ramp'! There was a lovely shot of a tripcock tester in the thread with the Ashfield House school photos a couple of days ago and for operation look back through the District Forum where I gave a full explanation of the working several months ago |
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Post by railtechnician on Dec 21, 2008 23:50:53 GMT
Some of the tripcock tester lights are very dim! I would like to think I would notice if one ever stayed on, but somewhere like Barons Ct or Upney, I'm not so sure ! I believe the ones with purple lenses may fall into that category but it may also be that the wrong wattage bulb has been fitted. It may not be possible to improve the light without changing the housing because there are several types of lampholder in use. In its wisdom some years ago the stores department rationalised the lamps it bought in to presumably to save money and for some fittings this left a choice of one bulb. |
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mrfs42
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Post by mrfs42 on Dec 22, 2008 11:05:52 GMT
There is a gauge on a ramp, bit like a set of rugby posts that the tripcock has to pass, and then repress a damp for the light to go out. I'm sure there is a photo somewhere. The tester is activated by a track circuit I think. Being pedantic that is of course 'depress a ramp'! There was a lovely shot of a tripcock tester in the thread with the Ashfield House school photos a couple of days ago and for operation look back through the District Forum where I gave a full explanation of the working several months ago Channelling Colin, from this thread: I can't speak for the TTs at Earls Court but I used to maintain the ones at Acton and sometimes those at Wood Green. The TT circuit is normally set up when the train drops onto the track on its approach side i.e. the first platform track at which time the lunar white TT lamp should illuminate at the headwall. If the tripcock is in gauge and correctly operates the TT ramp the TT lamp will extinguish otherwise it will remain alight and an audible alarm will be given, generally this is a bell on the platform but it may be elsewhere. I believe for Acton there are no bells on the station but the alarm will sound or be otherwise indicated at Earls Court Control room. In the case of a TT being fitted in a position where 'wrong road' moves may be made over it then it contains a trainstop motor which will hold the ramp down once operated but which will also pull the ramp down when the TT needs to be released for a 'wrong road' move. In this case a train dropping onto the track in which the TT is located (the second platform track in normal DOT) will operate the TT motor. Apart from a 'wrong road' move I am unaware of any circumstances in which a TT would be released unless it has been legitimately operated by a train's tripcock. Of course I am not infallible! |
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Post by ducatisti on Dec 22, 2008 11:35:35 GMT
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