Rotating Ground Signals - colours of the lights

GMaslin
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Rotating Ground Signals - colours of the lights

Postby GMaslin » Thu May 21, 2015 11:17 am

I'm going to incorporate rotating ground signals on my Saffron Walden layout. These will be the McKenzie and Holland GER type and as well as making them rotate I want them to display the correct colour lights which will be fed by fibre optic from a bulb or bulbs under the baseboard. However I can't find any reference regarding the colour of the lights. The LNER Constituent Signalling book by A.A.Maclean doesn't mention the light colours at all. The leaflet (GST3) produced by Model Signal Engineering for their 3mm scale ground signal mentions that there are three lamps (or at least three lenses that the light shines out of) but doesn't mention the colours. I assume the one in the middle of the target disc is red but what about the others? While writing this two subsidiary questions have come to mind. Firstly, why does it need three lights anyway? Secondly, assuming that the source of the light was an oil lamp, would it have been lit all the time or just at night?

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Noel
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Re: Rotating Ground Signals - colours of the lights

Postby Noel » Thu May 21, 2015 2:55 pm

Have you asked the GE Society about signal lamp lens colours? I would expect that they know if anyone does.

It would have been one lamp with three lenses [front, back and 90 degrees to one side between them] rather than three lamps. One was stop, one go, and I presume that the third was a backlight to show the signalman that the signal had responded to the lever.

The 1936 GWR General Appendix refers to signal lamps being removed each day during daylight, taken to the lamp room, cleaned, filled and relit. Presumably the expectation would be that the lamp should still be alight when removed for refilling, etc. The exception was 'long burning' lamps, which were attended to weekly, and were presumably the norm by then, at least in busy locations. There is also reference in the appendix to lines where the signal lamps are not lit during the summer - presumably such lines only operated in daylight hours in summer.

Noel
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Noel

GMaslin
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Re: Rotating Ground Signals - colours of the lights

Postby GMaslin » Thu May 21, 2015 3:38 pm

Thanks Noel,

Your suggestions for the purposes for the front, side and rear lights make sense. I will contact the GE Society for clarification, but my best guess would now be that the front light would be red to match the front face of the disc, or yellow to match a yellow disc if it can be passed at danger such as if for leading to a headshunt. The side lamp would then probably be green and the backlight probably white.

It makes sense for the lights only to be on at night, but that means if my layout is only operated in daylight (which it will be) then there's no need for me to fit working lights after all. I'll probably fit them anyway though as I like a challenge.

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grovenor-2685
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Re: Rotating Ground Signals - colours of the lights

Postby grovenor-2685 » Thu May 21, 2015 4:37 pm

It makes sense for the lights only to be on at night,

That's not quite what was said, when using lamps that would last only one day, the lampman would collect a batch, take them to the lamp room, clean refill, relight and then take them back, repeat for another batch. So the lights would only be out for the couple of hours this took. He's not going to turn up at dawn to collect the lamps and come back at dusk to take them back out. If 7 day lamps were in use then the excercise would only be done weekly.
Of course you would have to look very closely in daylight to see if the lamp was lit or not.
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Keith

John Palmer
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Re: Rotating Ground Signals - colours of the lights

Postby John Palmer » Thu May 21, 2015 4:52 pm

One of the photographs of rotating head GER shunt signals in Sandy Maclean's book on LNER constituents' signals clearly shows two lenses on the side and rear face of the lamp housing. With the addition of the lens on the face bearing the target this accounts for the reference to three lights being displayed. I agree with Noel that one of these will be the backlight. The need for such a backlight is given added weight by Maclean's comment at page 173 that 'A rotating lamp disadvantage was that movement vibration could extinguish the flame.'

I note that the caption to photograph of the signal at Chappel says that this had a yellow face. I would hope that your enquiry of the GE Society will reveal whether yellow-targeted signals exhibited a yellow aspect until cleared. What is of particular interest is the aspect displayed when the signal is cleared. I understand that in pre-grouping days a white light was used to indicate 'clear' until the coming of green, which was formerly used to indicate caution - 'White is right, red is wrong, green is gently go along.'

Is it not feasible to illuminate your models of such signals with a single fibre optic 'bulb' in the interior of the lamp housing and put appropriately coloured lenses into the sides of the housing, as in the prototype? You did say you relished a challenge!

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Noel
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Re: Rotating Ground Signals - colours of the lights

Postby Noel » Fri May 22, 2015 10:44 am

Sorry if I caused any confusion; I interpret the rule in the same way as Keith. According to pictures lamps were carried on a stick over one shoulder [up to six at a time from memory], so as Keith says, the lamps would be dealt with in small batches and then returned. 'Long burning' lamps would of course be lit for a week continuously.

As well as the white for 'all clear' some pre-group railways, I believe, used purple lights for 'danger' in subsidiary signals for a while, but I have no details. I think that the use of yellow for subsidiary signals that could be passed at 'danger' was a fairly late development in the 1930s, postdating the change to yellow for distant signals, and was not very common, many older signals remaining unchanged until closure or replacement by colour lights.

Noel
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Noel

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Guy Rixon
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Re: Rotating Ground Signals - colours of the lights

Postby Guy Rixon » Fri May 22, 2015 12:45 pm

Noel wrote:As well as the white for 'all clear' some pre-group railways, I believe, used purple lights for 'danger' in subsidiary signals for a while, but I have no details.l


I understand that the Cambrian used these colours in their running signals. The logic was that red and green were the established colours for ships' running lights and lamps of those colours ashore could mislead masters of coastal ships.

GMaslin
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Re: Rotating Ground Signals - colours of the lights

Postby GMaslin » Fri May 22, 2015 2:12 pm

Thanks to everybody for all these replies, and so quickly too. It now seems that I will be able to have my ground signals illuminated during the daytime (or most of it) after all. The real challenge would be to have a sub miniature white LED inside the ground signal with three coloured lenses. I suppose I could also build in a trembler circuit to make the output fluctuate to represent vibration of passing trains affecting the flame! The simplest approach though would be three separate LEDs of appropriate colours below the baseboard with three separate fibres going into the signal with the ends of the fibres cut at 45 degrees to send the light out sideways to the lenses. I'll be more than content with that amount of challenge. I guess my question to GERS will now have to specify the year I am representing as well as the location in order to firmly establish the appropriate colours.

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Noel
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Re: Rotating Ground Signals - colours of the lights

Postby Noel » Fri May 22, 2015 4:46 pm

Sorry to possibly dampen your enthusiasm, but don't forget Keith's comment
grovenor-2685 wrote:Of course you would have to look very closely in daylight to see if the lamp was lit or not.
Oil lamps are pretty feeble when compared to modern electric lighting.

Noel
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Noel


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