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Post by Deleted on Sept 30, 2019 18:29:36 GMT
Hey
I got a little problem, I'm wondering about the safety hoops that are installed so the district trains don't go into pic tunnels.
Do these hoops disconnect the power or put the next four signals to danger?
thanks
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Post by superteacher on Sept 30, 2019 19:08:20 GMT
Hey I got a little problem, I'm wondering about the safety hoops that are installed so the district trains don't go into pic tunnels. Do these hoops disconnect the power or put the next four signals to danger? thanks
Pretty sure they only affect the signals. |
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Post by countryman on Sept 30, 2019 19:15:37 GMT
Hey I got a little problem, I'm wondering about the safety hoops that are installed so the district trains don't go into pic tunnels. Do these hoops disconnect the power or put the next four signals to danger? thanks
Pretty sure they only affect the signals. You can see the one at Hounslow West at around 1:06: with an explanation of what happens if the system is activated. |
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Post by Dstock7080 on Sept 30, 2019 19:35:41 GMT
Do these hoops disconnect the power or put the next four signals to danger? thanks Pretty sure they only affect the signals. You can see the one at Hounslow West at around 1:06: with an explanation of what happens if the system is activated. Usually only one, the next automatic signal which is plated as an “X” signal. |
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Post by t697 on Sept 30, 2019 20:03:42 GMT
And I'm pretty sure a previous thread stated that they aren't filled with mercury any more.
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Post by Chris L on Sept 30, 2019 21:11:04 GMT
It was a great shame that the Heathrow Extension wasn't built to surface stock dimensions.
The 1973 stock is totally unsuitable for passengers with large suitcases.
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Post by Deleted on Sept 30, 2019 21:15:21 GMT
let's hope that TfL might realize that that is a good idea so they can implement it in the nTfL
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Post by superteacher on Sept 30, 2019 21:28:40 GMT
Short of spending billions on enlarging tunnels, the Heathrow branch will continue to use tube stock.
Let’s get back on topic.
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Post by Deleted on Sept 30, 2019 23:45:45 GMT
And I'm pretty sure a previous thread stated that they aren't filled with mercury any more. Conductive paint they are now but still glass trust me I have broken one in the past very easy to do |
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Post by Deleted on Sept 30, 2019 23:46:29 GMT
Do these hoops disconnect the power or put the next four signals to danger? thanks Pretty sure they only affect the signals. You can see the one at Hounslow West at around 1:06: with an explanation of what happens if the system is activated. Usually only one, the next automatic signal which is plated as an “X” signal. It puts them all to danger not just the X |
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Post by Deleted on Sept 30, 2019 23:46:51 GMT
Hey I got a little problem, I'm wondering about the safety hoops that are installed so the district trains don't go into pic tunnels. Do these hoops disconnect the power or put the next four signals to danger? thanks
Pretty sure they only affect the signals. Correct |
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Post by superteacher on Oct 1, 2019 5:01:10 GMT
And I'm pretty sure a previous thread stated that they aren't filled with mercury any more. Conductive paint they are now but still glass trust me I have broken one in the past very easy to do Hopefully not by attempting to drive a D stock towards Heathrow! 👍😂😂 |
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Post by Deleted on Oct 1, 2019 5:31:33 GMT
No I hit one from another don’t ask long story but I got one spare and they are rare as rocking house poop
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Post by norbitonflyer on Oct 1, 2019 6:09:52 GMT
It puts them all to danger not just the X Why would it do that? Surely only the signal immediately after the wrong turn (and its trainstop) needs to go to danger? Any behind the train will not stop it. Any further ahead will be in the tunnel and too late. I have broken one in the past very easy to do Isn't that the point of them? Have any ever been set off by an over-height train hitting them? |
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Post by Deleted on Oct 1, 2019 13:34:49 GMT
No they usually break by even the slightest knock or vibration
The signals that fail are the home signals going into Barons Court the hoop is situated near the A signal sorry cant remember the number off the top of my head
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roythebus
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Post by roythebus on Jan 16, 2020 23:22:12 GMT
Pity they don't install something similar at low bridges on the roads. Break one and a huge barrier springs up out of he road to make sure the overheight thing stops.
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Post by PiccNT on Jan 17, 2020 0:33:40 GMT
No they usually break by even the slightest knock or vibration The signals that fail are the home signals going into Barons Court the hoop is situated near the A signal sorry cant remember the number off the top of my head I believe it is just the X signals (X647C and X412A) that return to danger (X647C) or remain at danger (X412A). That's what the signalling diagrams suggest and in the case of Barons Court, some time ago X647C failed (just that signal) and it was a surface stock detector relay fault that caused the problem, to my recollection! |
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Post by rheostar on Jan 17, 2020 10:58:29 GMT
No I hit one from another don’t ask long story but I got one spare and they are rare as rocking house poop Was that the one at Barons Court a few years ago? |
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Post by Deleted on Jan 17, 2020 13:24:20 GMT
No I hit one from another don’t ask long story but I got one spare and they are rare as rocking house poop Was that the one at Barons Court a few years ago? Yes it was Barons Court and it wasn’t years ago. We did go through a spell in the early 00’s of contractors even though couldn’t prove it throwing ballast up to them which caused them to break. Last time it did break was around 18 months to 2 years ago now |
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Post by rheostar on Jan 17, 2020 13:38:29 GMT
Was that the one at Barons Court a few years ago? Yes it was Barons Court and it wasn’t years ago. We did go through a spell in the early 00’s of contractors even though couldn’t prove it throwing ballast up to them which caused them to break. Last time it did break was around 18 months to 2 years ago now Think I was on shift for that one!  |
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Post by Deleted on Jan 17, 2020 14:29:37 GMT
I know I was  |
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Post by spsmiler on Jan 17, 2020 20:13:10 GMT
A photo from my website which I think will help explain the topic to people who have never seen these contraptions before. This example is at Finchley Road, so whilst the location is different to that mentioned in this thread's tittle, what is seen here (and the purpose) is the same. I feel sure the downward hanging hoops have now been removed - done after the physical splitting of the Jubilee and Metropolitan lines.  |
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Post by Deleted on Jan 17, 2020 22:45:07 GMT
Yes they have been removed.
None of the ones at Barons Court contain mercury the glass is painted with conductive paint
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Post by zbang on Jan 18, 2020 0:54:48 GMT
None of the ones at Barons Court contain mercury the glass is painted with conductive paint
Wouldn't it have been easier to replace them with an electric eye setup controlling a relay? (The glass tubes might have been new technology 100 years ago, but not 50.)
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Post by brigham on Jan 18, 2020 8:32:30 GMT
Wouldn't it have been easier to replace them with an electric eye setup controlling a relay? (The glass tubes might have been new technology 100 years ago, but not 50.)
Hardly. It would involve installing and aligning an electric-eye setup, with its associated power supply (and liability to go wrong), instead of a passive, intrinsically fail-safe glass tube. |
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class411
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Post by class411 on Jan 18, 2020 9:54:26 GMT
None of the ones at Barons Court contain mercury the glass is painted with conductive paint Wouldn't it have been easier to replace them with an electric eye setup controlling a relay? (The glass tubes might have been new technology 100 years ago, but not 50.)
It would be a lot harder to make such a set-up fail-safe, and in doing so it would make the system more prone to false positives as anything (birds, leaves, litter) that interrupted any one of the beams would halt the system. Presumably once the system has been activated it is not that easy to reset as someone has to positively ensure that there is not any possibility of an oversized train present |
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Post by rheostar on Jan 18, 2020 14:14:27 GMT
I know I was We were probably talking to each other. ;-) |
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Post by zbang on Jan 18, 2020 17:54:25 GMT
It would be a lot harder to make such a set-up fail-safe, and in doing so it would make the system more prone to false positives as anything (birds, leaves, litter) that interrupted any one of the beams would halt the system. Presumably once the system has been activated it is not that easy to reset as someone has to positively ensure that there is not any possibility of an oversized train present
I'm not sure of the "much harder" part, EE setups are used for machine safety all the time (and they're non-destructably testable). Leaves/birds? Multiple sensors where some enable detection by the others. And reset is not an issue if the "reset" must be done on-site. This isn't a difficult problem.
OTOH they would cost a fair bit more than some painted glass tubes, assuming that the tubes are hardly ever tested or tripped.
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roythebus
Pleased to say the restoration of BEA coach MLL738 is as complete as it can be, now restoring MLL721
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Post by roythebus on Jan 18, 2020 20:36:18 GMT
It may be old, but it's simple and it works. It ain't broke, don't fix it.
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rincew1nd
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Post by rincew1nd on Jan 18, 2020 20:46:42 GMT
It ain't broke, don't fix it. Even if it costs a fortune to maintain? |
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