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GWR night time aspects of subsidery/disc signal


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Reading various books and more lately the “ GWR signalling practice “ brings me to ask some questions. I think we had a tangential discussion that mentioned this 

 

there is a paragraph of discussion , in the above book, concerning the decision / provision of red or white lights in discs and some signals. 

 

My understanding was that the use of the non tappet locking , prevent certain conditional locking arrangements , meaning that such installations could not pull off a disc , in both normal and reverse , once it’s associated point was locked. This meant , as I understand it that the light in the disc was white , if the movement was allowed through this disc , whereas if no backing movement was antipicated , the light was red ( ie in the direction where the disc had to passed at when “on” ) 

 

however , am I correct that this situation changed as the gwr adopted tappet locking.  My layout is derived from badminton , and looking at the locking table , it does seem , as I understand it , that the discs could be released for either route 

 

would that mean therefore that later GWR constructed lines , would largely have red lights in the discs 

 

GWR signalling practice , doesn’t seem to draw attention to this, so am  I wrong  here, the book does mention BR (W) changed the policy 

 

so do I need to determine what my discs should display , ie red or white or can I assume conditional locking and have all red  lights or am I missing something 

 

thanks 

 

Dave 

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27 minutes ago, Junctionmad said:

Reading various books and more lately the “ GWR signalling practice “ brings me to ask some questions. I think we had a tangential discussion that mentioned this there is a paragraph of discussion , in the above book, concerning the decision / provision of red or white lights in discs and some signals.

 

There is a "Disc Signal" co-sited with (maybe just slightly in advance of) the Down Home Signal at Moretonhampstead (shown in the above book) and I wondered what colour the  lens would have been in the "On" position. As the "Disc Signal" is to allow movement in advance of the Home Signal I would think that the Lens would have been white?  Maybe the same in your scenario?

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>>>>My understanding was that the use of the non tappet locking , prevent certain conditional locking arrangements , meaning that such installations could not pull off a disc , in both normal and reverse , once it’s associated point was locked. This meant , as I understand it that the light in the disc was white , if the movement was allowed through this disc , whereas if no backing movement was antipicated , the light was red ( ie in the direction where the disc had to passed at when “on” ).....

 

Sorry, but I'm baffled by exactly what you are trying to say here :-)

 

The Stationmaster hopefully will give us a definitive answer in due course, but in the meantime:-

 

1. A disc signal at the toe of set of points could in theory read for either route. In practice, if the locking requirements for each route were different, then you needed conditional locking capability to do that. If the frame design did not allow for conditional locking, then the signal would read only for one route (usually the diverging route).

 

2. If a signal could read for both routes, then usually the stop aspect would be red. If it could only read for one route, and therefore had to be passed at 'on' for the other route, then at some date the GWR adopted the practice of giving those white lights.

 

3. In the case of Moretonhampstead (one of my favourite places <g>), the disc read into the loop whilst the Down Home read ahead on the main line. Effectively the two signals were (almost) co-located, so a movement towards the station on either the main or the loop would have had either one or the other signal off - probably :-)  IMHO the disc may well have been red therefore, but I don't know for sure.

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6 hours ago, Junctionmad said:

Reading various books and more lately the “ GWR signalling practice “ brings me to ask some questions. I think we had a tangential discussion that mentioned this 

 

there is a paragraph of discussion , in the above book, concerning the decision / provision of red or white lights in discs and some signals. 

 

My understanding was that the use of the non tappet locking , prevent certain conditional locking arrangements , meaning that such installations could not pull off a disc , in both normal and reverse , once it’s associated point was locked. This meant , as I understand it that the light in the disc was white , if the movement was allowed through this disc , whereas if no backing movement was antipicated , the light was red ( ie in the direction where the disc had to passed at when “on” ) 

 

however , am I correct that this situation changed as the gwr adopted tappet locking.  My layout is derived from badminton , and looking at the locking table , it does seem , as I understand it , that the discs could be released for either route 

 

would that mean therefore that later GWR constructed lines , would largely have red lights in the discs 

 

GWR signalling practice , doesn’t seem to draw attention to this, so am  I wrong  here, the book does mention BR (W) changed the policy 

 

so do I need to determine what my discs should display , ie red or white or can I assume conditional locking and have all red  lights or am I missing something 

 

thanks 

 

Dave 

Earlier forms of GWR locking did not allow conditional locks/releases so c. the 1890s the GWR engaged in a major programme of converting many independent ground disc signal danger lights from red to white.  White lights were also used in some cases in backing signals and, according to various GWR operational documents, siding signals.  The principle was very simple in that if a signal could not be lowered for a movement then a white light was used to ensure there was no need to pass a red light AND provided the movement was limited by a signal capable of showing a red light.

 

Looking at the locking table for Chipping Sodbury (which was contemporaneous with Badminton of course) there were definitely some white light discs and the 1942 locking suggests that some of them lasted after the introduction of tappet locking ('m not sure if the tappet locking there was additional or a total replacement for the original frame which had double twist locking.  Badminton also originally had a double twist frame with some tappet locking added in 1940.  WR white light discs definitely lasted into the 1980s in some places only being swept away by resignalling or, alas at many places, by earlier closures and rationalisation.

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SO , would you and others help me to identify what disks would be white lighted , in my derivation of Badminton, or should i just assume all tappet locking and all red lights 

You  all seen this before ( and it is currently being slightly renumbered due to a new lever frame being built  )

Obviously certain ones are clearly red-light .

Screenshot 2019-11-24 23.41.35.png

 

I should add , that in a model railway context, the drivers of this layout, would prefer to get positive confirmation from a ground disc , being pulled off , for either route , rather then assuming they could set back against a disc at danger. Verbal comms to drivers on this size of layout isn’t as easy as it seems , and with several drivers things can get confused 

 

hence I wonder how practical it is to have white light discs 

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Righto reading from left to right and top to bottom on the diagram -

 

9 red

11 red

18 white

15 red

14 white

21 white

13 red. (it would be white if it was a single disc)

19 white

24 white

26 red. (should actually be white with the lie of 25 points reversed from what is shown on the diagram - 25 & 27 should be arranged to work as a crossover)

30 red

33 red

39 red

34 white

 

White light ground discs and backing signals etc could only be passed with the permission of  the Shunter or Guard, who in turn would have first agreed the movement with the Signalman.  accordingly they should not be cind fused with yellow arm discs etc which may be passed at danger if the points are not standing reverse.

 

From the description of the way your layout will be worked I would agree that it would be difficult to use white light ground discs.  Provided the locking secures all routes reading from each signal you could quite happily use red light discs and it wouldn't be easy either to use flags (small ones no doubt) when there is a risk of Drivers confusing who the flag applies to.

 

 

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