What signal is this? And how did it work?

[M7R]

I recently acquired this signal but I am unsure what sort it is? Is it a search light multi colour one? I thought they were a LNER thing? This seems to be BR Western region? It’s wired up with a 6v bulb but I’m not sure if this is original? Anyone know anything about it or where I can read more about it and how it worked?

Thanks

 

[Taunton]

It looks to me, as you suspected, like a GWR searchlight signal, of the type that were installed in the 1930s at major points like Paddington or Bristol, and then replaced by BR multi-aspect schemes in the 1960s-70s. They broadly showed the same indications, in the same manner, as semaphores did at night.

A quick web search gave this picture at Paddington; the two on the left:

File:Paddington 1 railway station 2039175.jpg - Wikimedia Commons

commons.wikimedia.org

 

[John Webb]

The main part of the mechanism appears to be missing, There would have been a pendulum-like 'vane' between the lamp (probably a 12v one, not 6v) and the lens, moved by a solenoid. Depending on whether the signal was a 'stop' or 'distant' the 'vane' would have a red or yellow filter that would be in position between lens and lamp when the solenoid wasn't operated. On operation of the solenoid the vane would be moved to give a green aspect.

The GWR ones only showed two aspects - the LNER/BR(ER) usually displayed three aspects by using a form of polarised relay to move the vane from the central red position to either yellow or green.

 

[Railsigns]

The signal appears to show a yellow aspect in the front view and a green aspect in the side view, so the vane with the coloured roundels would seem to be present.

 

[Taunton]

All of the LMS, LNER and GWR took their initial colour light signals from USA practice, and their first installations were imported from there, later being made by UK companies under licence. They introduced typical USA features, like 'Approach lit' to save battery power, and the positive/negative/no current approach to handle three aspects.

Here's a Delaware & Hudson installation at Saratoga, northern New York State, where the units look very like the opening photo (and what the GWR used).

A searchlight bracket mast on the Delaware and Hudson at Saratoga Springs, New York. There are two main types of… | Railroad photography, Railroad, Railroad lights

Apr 25, 2015 - A searchlight bracket mast on the Delaware and Hudson at Saratoga Springs, New York. There are two main types of signaling aspect systems found in North America, Speed Signaling and Weak Route Signaling. Speed signaling transmits information regarding how fast the train must be...

www.pinterest.co.uk

 

[M7R]

It looks to me, as you suspected, like a GWR searchlight signal, of the type that were installed in the 1930s at major points like Paddington or Bristol, and then replaced by BR multi-aspect schemes in the 1960s-70s. They broadly showed the same indications, in the same manner, as semaphores did at night.

A quick web search gave this picture at Paddington; the two on the left:

File:Paddington 1 railway station 2039175.jpg - Wikimedia Commons

commons.wikimedia.org

Thanks, now I know I’m on the right track I can do some more digging on the history, how they worked etc. I suspect the chance of me finding some internals is slim

The main part of the mechanism appears to be missing, There would have been a pendulum-like 'vane' between the lamp (probably a 12v one, not 6v) and the lens, moved by a solenoid. Depending on whether the signal was a 'stop' or 'distant' the 'vane' would have a red or yellow filter that would be in position between lens and lamp when the solenoid wasn't operated. On operation of the solenoid the vane would be moved to give a green aspect.

The GWR ones only showed two aspects - the LNER/BR(ER) usually displayed three aspects by using a form of polarised relay to move the vane from the central red position to either yellow or green.

I did suspect there was something missing. I’m sure I have seen something similar that was a white light at some level crossings? Like a confirmation the crossing was closed correctly but I could be wrong.

Thanks for the info on how it works, for now I plan to mount a modern light in it and will use a filter to replicate the green or yellow aspect. I will try and do some research on the internals though, sounds very interesting.

The signal appears to show a yellow aspect in the front view and a green aspect in the side view, so the vane with the coloured roundels would seem to be present.

The green is just the bbq gas bottle, the mechanism inside is missing bar the lamp.

For now both are being dimly lit with a bunch of 100 solar powered led fairy lights.

 

[Taunton]

If it's a GWR signal it will just have shown two aspects, like a semaphore did at night; red/green for a Stop, and Yellow/Green for a Distant. Two were commonly found one over the other, like a Stop and Distant semaphore. The normal arrangement was the lamp always burned, if current was supplied from the signalbox this pulled up the colour filter to the green aspect, if no current it fell; by gravity, to show the more restrictive yellow or red. The lamp was, separately, battery powered locally, power for the lamp did not come from the wires connecting to the signalbox.

The LNER went for an alternative mechanism, with three aspects in a U-shaped slide, yellow one side, green the other, and red at the bottom. The mechanism detected whether the current was positive or negative. Positive current made the solenoid pull it one way to green, negative current pulled it to the other end to show yellow. No current, and the weighted slide fell to the bottom and showed red. A slight disadvantage was as it stepped up indication from yellow to green, the display momentarily passed through red, but presumably drivers got used to it.

The LNER also used a further USA concept, Approach Lit lamps, where the lamp was unlit, whatever the slide had been moved to, until approach track circuits detected there was a train in section, when they switched on the lamp. This was done to save battery power to the lamp, for obviously for most of the time there is no train approaching. Maintenance of batteries became critical for such signals - the GWR, which employed similar lineside batteries and connections for their AWS ("ATC") ramps, found the dropoff in lineside maintenance during WW2 meant on a long journey crews would likely get one or more false warnings because the battery had gone flat.

 

[D6130]

A slight disadvantage was as it stepped up indication from yellow to green, the display momentarily passed through red, but presumably drivers got used to it.

Yes, I remember approaching Darlington from the Eaglescliffe direction in the front of a DMU in the mid-1960s and watching searchlight signals changing from yellow - through red - to green. However the movement of the slide was so quick that it just looked like a brief flash of orange.

 

[Taunton]

Yes, I remember approaching Darlington from the Eaglescliffe direction in the front of a DMU in the mid-1960s and watching searchlight signals changing from yellow - through red - to green. However the movement of the slide was so quick that it just looked like a brief flash of orange.

This worked OK, until the rather short-lived overlap on the GEML between the last LNER searchlights and the first TPWS installations. For whatever reason, it was initially designed to drive TPWS off the actual signal colour slide mechanism. If the signal was just stepping up from yellow to green as the train passed over the TPWS loop at speed, a not unknown combination, the signal, and the TPWS, thus momentarily had a red, and an emergency brake application occurred. A fix had to be determined quite rapidly.

 

[John Webb]

Thanks, now I know I’m on the right track I can do some more digging on the history, how they worked etc. I suspect the chance of me finding some internals is slim....
....I did suspect there was something missing. I’m sure I have seen something similar that was a white light at some level crossings? Like a confirmation the crossing was closed correctly but I could be wrong.....

Glad to have been of some help. The white light at some automatic open (ie without any barriers) level crossings is a fixed white light which flashes to indicate to the train driver the warning signals for road traffic have operated correctly and it should be safe for the train to proceed.

 

[eldomtom2]

All of the LMS, LNER and GWR took their initial colour light signals from USA practice, and their first installations were imported from there, later being made by UK companies under licence. They introduced typical USA features, like 'Approach lit' to save battery power, and the positive/negative/no current approach to handle three aspects.

However IIRC apart from the Mirfield speed signalling trial they only took inspiration from American practice on the technical side, and not on the operational side.

 

[M7R]

Glad to have been of some help. The white light at some automatic open (ie without any barriers) level crossings is a fixed white light which flashes to indicate to the train driver the warning signals for road traffic have operated correctly and it should be safe for the train to proceed.

Ahhh thanks for confirming I wasn’t going mad with regards to a white light at a crossing.