Westinghouse Colour Light Signal Hood Dimensions & An Introduction

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    Westinghouse Colour Light Signal Hood Dimensions & an Introduction

    I have just registered on the forum- whilsst I never resgistered on the old version, I did find it very useful on the occasions I refer to it, so very good to see it return.

    I am a bit of a general tinkerer, and recently had a bit of a foray into restoring disused signals. The first is a colour light ground signal- I have put a short write up on my project website http://www.superpants.net.

    I am currently working on a Westinghouse 4 aspect colour light signal. This is nearing completion, but I’m contemplating what to do about lens hoods. I have the original long hoods, but these are really a bit excessive for display in the garden. If I have understood correctly these were offered with a shorter hood. Would anyone have dimensions, or even better a drawing for the shorter hood? I can then make a decision whether to cut down, or make some new ones.

    I’ll do a write up when I have finished the restoration.

    John WebbJohn Webb

    I’ve JPG files of a Westinghouse leaflet on their standard colour light signals and this gives a dimension of 305mm/12 inches for the hood length. It makes no mention of a shorter hood being available, even under the final ‘Non-standard’ listings at the end of the leaflet.

    We have a ground-mounted three-aspect Westinghouse signal at St Albans South on our lawn and have found no problem with the standard length hoods.

    Please PM me with your e-mail address if you want any further information.

    AvatarMike Hodgson

    But were the long hoods original ?

    I was under the impression they were an ARP precaution for WW2 to make signals less visible to enemy aircraft, albeit with limited effectiveness.  Although railway facilities were seen as a target, the main problem would have been that the ability to see signals along a route which would have aided aircraft navigating towards any target, especially when everything else was in blackout.  As an RAF pilot in the 1980s my brother once commented  to me that from a helicopter low over the Wash on a clear night the ECML could be seen as a string of evenly spaced  green lights.  Once the war was over any air-raid dimmer switches could simply be be left at bright and there would be no great merit in shortening hoods.

    The shorter hoods on post war  signals served to provide a degree of protection against reflections in some positions of the sun, now less of an issue with LEDs. Another design consideration is the risk of accretion of snow

    If the hoods seem a bit much in the garden, doesn’t the backing shroud also seem a bit OTT?  I assume you have it on a shorter post than would be normal too.  You could do as John has done and ground-mount it – if it’s in the front garden, perhaps even fit it with a PIR detector!  You’ll need to make sure people don’t mistake it for a traffic light.

    Nice job on the lanterns also the GPL but it’s a pity you photographed it with all 3 lights on – unless you aimed to re-create a wrong side failure 🙂

    John WebbJohn Webb

    To add to Mike’s post our ground-mounted 3-aspect signal does not have the backing shroud fitted. It replicates a similar signal fitted at ground level between the up and down slow lines where there was very limited clearance. See our Newsletter 17 at http://www.sigbox.co.uk/eblock/services/resources.ashx/000/296/633/Newsletter_17_pdf.pdf page 2 for more details. It was later moved to the lawn and can be seen at http://www.sigbox.co.uk/sigbox/news/news_2014.eb about halfway down the page.

    We also have a 4-Aspect demo – take a look at http://www.sigbox.co.uk/sigbox/news/news_2011.eb under March and April – about 2/3rd of the way down the page.

    We too have a GPL signal similar to yours. We’ve mounted it on a ‘concrete’ block (actually painted wood!)  The original 110 volt bulbs were replaced with 12V 5W car tail-lamp bulbs and are supplied with 12 volts DC from an external source. A timer built into the base switches it from ‘stop’ to ‘clear’ – roughly 30 secs at the former and 15 secs at the latter. A plug-in switch allows us to operate the signal manually – much appreciated by our young visitors. Oddly I can’t find a published photo of it!


    • This reply was modified 1 week, 3 days ago by Inspector Boggins. Reason: Incompatible code removed
    Avatardavid woodcock

    I can confirm that the long hoods were fitted as an ARP in the late summer of 1940, the task being considered so urgent that work continued 24 hours a day, even during actual air raids, until every signal had been changed. A Southern S&T technician who worked on the task told me (about 60 years ago!) that they quickly realised that bombs were much less of a hazard than aircraft-mounted machine guns. The initial ARP for c/l signals was dimming by switching in a second bulb in series but when the Battle of Britain started it rapidly became clear that that wasn’t sufficient.

    • This reply was modified 1 week ago by Inspector Boggins.

    Thanks everyone for the replies. Nice to get a friendly and comprehensive set of answers.Been a bit of a busy weekend so just getting round to answering now.

    Thaks for for confirming the normal length. I have measured mine at 2ft long, so pretty substantial.

    I have the signal mounted on the type of cast iron base that bolts down (not post mounted), in turn bolted down to a wooden frame. This puts the botton of the signal about a 8 inches off the ground, so the bottom aspect is very close to the ground. The long hoods therefore make it really difficult to see the bottom two aspects, hence the desire to change. I think I’ll mock up a carboard hood at 12″ long and trial it.

    Thanks also for the links- good to see what you have done. Will get round to making a visit at some point!

    I like the idea of mounting the GPL on a ‘concrete’ block- I might have to boorow that idea!

    I will PM you seperately.

    Mike/ David
    Thanks for the info on them being fitted as an ARP. I had assumed the signal (and the 3 aspect I have also to be restored with long hood) was post war. This would therefore date it it to pre 1940. Nice to find that out!

    I have the backing shroud on, but it’s up against a dark coloured fence so doesn’t seem too over the top!

    Thanks for the nice comments. I now realised I have made a rookie error on photographing the GPL with all lamps lit! I took the photo just as I finished it and powered up. Didn’t think about taking photos with it lit as used. I should probably go and do that!

    I have an electronic engineer friend who is putting together a sequencer to automatically cycle the lights (They want one for themself). I like the idea of supplementing this with manual switches- Plenty of bits in the garage to do that with!

    AvatarMike Hodgson

    If you want a simple sequencer to cycle through, such things are available quite cheaply from various small electronics firms catering to the model railway market.  Typically a 555 timer is initiated by a passing train operating a reed switch, infra red beam or similar momentary trigger to put the signal back to danger behind it.  However you might have to boost the output stage to suit, since model railway signals tend to be LEDs, although some products will be able to operate relays.

    On the real railway, circuitry tends to be standardised in overall approach to ensure that the design is fail safe.  3-aspect signals are typically controlled by two relays one called the HR which when energised changes from red to a proceed aspect.   The other is called the DR and it decides whether that aspect should be Yellow  or Green (a third relay, the HHR is used for double yellow in 4-aspect signals).  The relay coils are energised when any relevant levers, track circuits, lamp proving or other relays and controls are all in their required states.  In the case of the DR, it only picks up if both its own HR and that of the next signal have picked up and automatically falls back to show a more restrictive aspect should that cease to be true.  Relays might live in one of those grey lineside cabinets or in a relay room.



    Thanks Mike for the extra information- very helpful! I’ll refer back to it once I start sorting sequencer installation out.



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