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Gantry
Feb 1, 2017 19:20:41 GMT
Post by dave1 on Feb 1, 2017 19:20:41 GMT
Found this photo just wondering what the things are coming down from the gantry are. Click
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Gantry
Feb 2, 2017 0:01:46 GMT
Post by Nortube on Feb 2, 2017 0:01:46 GMT
I've seen these in various places, more frequently fixed direct to the gantry, bridge etc. rather than suspended from it. A rectangular metal plate directly above the track. I've always assumed that they were there to deflect the steam away from the structure above and thus avoiding any potential heat damage, especially where they are cable run gantries.
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Gantry
Feb 2, 2017 11:43:59 GMT
Post by dave1 on Feb 2, 2017 11:43:59 GMT
I've seen these in various places, more frequently fixed direct to the gantry, bridge etc. rather than suspended from it. A rectangular metal plate directly above the track. I've always assumed that they were there to deflect the steam away from the structure above and thus avoiding any potential heat damage, especially where they are cable run gantries. Thanks I had forgot all about that steam trains ran over some of those tracks. I thought it might have been to stop a build up of snow before going into the tunnel but that idea is a joke compared to what you have said.
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Gantry
Feb 2, 2017 13:31:25 GMT
Post by railtechnician on Feb 2, 2017 13:31:25 GMT
I've seen these in various places, more frequently fixed direct to the gantry, bridge etc. rather than suspended from it. A rectangular metal plate directly above the track. I've always assumed that they were there to deflect the steam away from the structure above and thus avoiding any potential heat damage, especially where they are cable run gantries. Thanks I had forgot all about that steam trains ran over some of those tracks. I thought it might have been to stop a build up of snow before going into the tunnel but that idea is a joke compared to what you have said. Bearing in mind the Central line location I believe them to be Surface Stock Detectors although they are not the usual 'U' tubes as seen in most locations where surface stock might inadvertently be signalled into tube tunnels.
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Gantry
Feb 2, 2017 15:41:52 GMT
Post by hangerlanejn on Feb 2, 2017 15:41:52 GMT
Thanks I had forgot all about that steam trains ran over some of those tracks. I thought it might have been to stop a build up of snow before going into the tunnel but that idea is a joke compared to what you have said. Bearing in mind the Central line location I believe them to be Surface Stock Detectors although they are not the usual 'U' tubes as seen in most locations where surface stock might inadvertently be signalled into tube tunnels. Looking at the picture(s) in the OP, the shape of the metalwork looks very like the standard shape for smoke deflectors. Overheight train detectors are usually in the form of three mercury-filled 'U' shaped tubes, which, when broken, breaks a circuit which the replaces the signal protecting the tunnel mouth to Danger, much as railtechnician says. These two objects are situated in rear of the points on the EB so would activate whichever route an overheight train might use, and also cover the WB line, where an overheight detector would seem a little pointless. It would appear that steam-hauled trains didn't use the WB Back platform as there is no deflector over that line.
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Gantry
Feb 2, 2017 16:59:56 GMT
Post by dave1 on Feb 2, 2017 16:59:56 GMT
Thanks I had forgot all about that steam trains ran over some of those tracks. I thought it might have been to stop a build up of snow before going into the tunnel but that idea is a joke compared to what you have said. Bearing in mind the Central line location I believe them to be Surface Stock Detectors although they are not the usual 'U' tubes as seen in most locations where surface stock might inadvertently be signalled into tube tunnels. I did not even think of surface stock detectors.
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Gantry
Feb 2, 2017 17:07:55 GMT
Post by dave1 on Feb 2, 2017 17:07:55 GMT
Bearing in mind the Central line location I believe them to be Surface Stock Detectors although they are not the usual 'U' tubes as seen in most locations where surface stock might inadvertently be signalled into tube tunnels. Looking at the picture(s) in the OP, the shape of the metalwork looks very like the standard shape for smoke deflectors. Overheight train detectors are usually in the form of three mercury-filled 'U' shaped tubes, which, when broken, breaks a circuit which the replaces the signal protecting the tunnel mouth to Danger, much as railtechnician says. These two objects are situated in rear of the points on the EB so would activate whichever route an overheight train might use, and also cover the WB line, where an overheight detector would seem a little pointless. It would appear that steam-hauled trains didn't use the WB Back platform as there is no deflector over that line. I have found a photo of a surface stock detector at Hounslow Central Click Would they have had a detector for the route to Snaresbrook as it was all open although some of the bridges could have been a bit low.
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Gantry
Feb 24, 2017 18:49:14 GMT
Post by Nortube on Feb 24, 2017 18:49:14 GMT
Looking at the photo of East Finchley that was linked to in the yellow shunt signals thread, [ click here for photo ]the gantry clearly shows the smoke deflectors on the roads to platforms 2 and 3. I suspect that the slightly lower device on the gantry on the road to platform 4 was originally a smoke deflector (when main line trains used platform 4 towards Highgate Depot during platform reconstruction) and this was later used for the train detector mercury tubes. It's hard to tell if the tubes are in place or not in the photo. The detector was removed in July 1973, just before I came on the job. Edit On reflection, the device on the gantry to platform 4 may not have served as a smoke deflector originally, and just been the fitting for the train detector.
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Gantry
Feb 25, 2017 11:51:13 GMT
Post by railtechnician on Feb 25, 2017 11:51:13 GMT
Looking at the photo of East Finchley that was linked to in the yellow shunt signals thread, [ click here for photo ]the gantry clearly shows the smoke deflectors on the roads to platforms 2 and 3. I suspect that the slightly lower device on the gantry on the road to platform 4 was originally a smoke deflector (when main line trains used platform 4 towards Highgate Depot during platform reconstruction) and this was later used for the train detector mercury tubes. It's hard to tell if the tubes are in place or not in the photo. The detector was removed in July 1973, just before I came on the job. Edit On reflection, the device on the gantry to platform 4 may not have served as a smoke deflector originally, and just been the fitting for the train detector. Needs a better photo! Often the way when attempting to definitively identify something !
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Gantry
Feb 25, 2017 18:57:08 GMT
Post by dave1 on Feb 25, 2017 18:57:08 GMT
If that photo was a lot better like RT says it would help a lot. I did a search but the photos are more modern although there is still something over the SB line with the line to the depot loosing its one. The photo must have been taken before the mercury tubes were installed.
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