Historical signal question

[Islineclear3_1]

My memory is hazy now but on a signalling diagram, what did a distant signal mean when half of it was painted black (towards the fishtail)?

I can't find a decent picture, but an example would be a home and distant on the same post (e.g. Advanced Starter and ??) Was this a fixed distant?

 

[Tomnick]

My memory is hazy now but on a signalling diagram, what did a distant signal mean when half of it was painted black (towards the fishtail)?

I can't find a decent picture, but an example would be a home and distant on the same post (e.g. Advanced Starter and ??) Was this a fixed distant?

Motor worked.

 

[Railsigns]

It means the signal is power-operated. Semaphore stop signal and disc signal symbols may also have a solid black end for this reason.

 

[Islineclear3_1]

Aha, cheers guys

 

[Elecman]

My memory is hazy now but on a signalling diagram, what did a distant signal mean when half of it was painted black (towards the fishtail)?

I can't find a decent picture, but an example would be a home and distant on the same post (e.g. Advanced Starter and ??) Was this a fixed distant?

motor operated

 

[Ediswan]

It means the signal is power-operated. Semaphore stop signal and disc signal symbols may also have a solid black end for this reason.

Out of nothing more than curiosity, how does it help the driver to know how the signal is operated - different failure modes ?

 

[hexagon789]

Out of nothing more than curiosity, how does it help the driver to know how the signal is operated - different failure modes ?

I thought it was on the diagram, not the physical signal?

So it would be for the aid of signallers.

 

[Railsigns]

Out of nothing more than curiosity, how does it help the driver to know how the signal is operated - different failure modes ?

It's only the symbol that has a black end, not the actual signal arm.

Similarly, a horizontal line along the middle of a semaphore arm symbol indicates that it's fixed, but this doesn't appear on the actual signal.

 

[Ediswan]

It's only the symbol that has a black end, not the actual signal arm.

Thanks. I missed that.

 

[Cheshire Scot]

So it would be for the aid of signallers.

Motorised signals - and points - had shortened lever heads. This reminded the signaller not to give a hard pull as the lever was not operating a potentially lengthy signal wire or point rodding.

 

[edwin_m]

Sometimes a motorised distant was put underneath a wire-worked stop signal on the same post. I think this would have been to simplify the "slotting" which prevented the distant being cleared when the stop signal was at danger. Sometimes when the stop signal was replaced to danger it dropped back quickly, but the motorised distant took a bit longer so for a short time there was the illegal combination of a distant "off" underneath a stop signal showing danger. The driver would not see this except in an emergency, as their train would already have passed it.

 

[Taunton]

The GWR used a lot of these which were beyond physical pulling from the box (the LMS went for colour light distants instead). As I understood it they did not initially have batteries (though later ones did), but a hand-crank generator in the signalbox known to all as the "hurdy-gurdy", after the old wind-up misical instrument, whose operation it resembled. They were used for motor points as well.

Installed on the distants through Taunton in the 1930s scheme, because of the short distances between boxes they were all slotted on double home/distant posts. The home above was conventional mechanical wire pull from the adjacent signalbox. This led to the unusual position that when the home was returned to danger after the train passed, it would clang back instantly with the normal GWR positive snap-action, whereas the distant would take up to 10 seconds to return, somewhat jerkily, back to the horizontal. I always used to think I should take a photograph at this precise moment showing them displaying what was theoretically impossible.

** - I see the post above has just said the same, during the half a day it took me to respond!

 

[edwin_m]

The GWR used a lot of these which were beyond physical pulling from the box (the LMS went for colour light distants instead). As I understood it they did not initially have batteries (though later ones did), but a hand-crank generator in the signalbox known to all as the "hurdy-gurdy", after the old wind-up misical instrument, whose operation it resembled. They were used for motor points as well.

Installed on the distants through Taunton in the 1930s scheme, because of the short distances between boxes they were all slotted on double home/distant posts. The home above was conventional mechanical wire pull from the adjacent signalbox. This led to the unusual position that when the home was returned to danger after the train passed, it would clang back instantly with the normal GWR positive snap-action, whereas the distant would take up to 10 seconds to return, somewhat jerkily, back to the horizontal. I always used to think I should take a photograph at this precise moment showing them displaying what was theoretically impossible.

** - I see the post above has just said the same, during the half a day it took me to respond!

Would that fail safe? I assume, as with a wire-worked distant, that it ought to revert to caution if it lost power.

I'm not really sure why it was worth motorising an isolated semaphore distant. A colour light would probably be cheaper and more reliable, as well as not requiring a fogman (but did the GWR exempt themselves from that on the grounds of having ATC?). Slightly different matter if it was underneath a different box's starter. when a colour light combined with a semaphore might well confuse (although that didn't prevent it being used sometimes).

 

[Taunton]

Would that fail safe? I assume, as with a wire-worked distant, that it ought to revert to caution if it lost power.

I'm not really sure why it was worth motorising an isolated semaphore distant. A colour light would probably be cheaper and more reliable, as well as not requiring a fogman (but did the GWR exempt themselves from that on the grounds of having ATC?). Slightly different matter if it was underneath a different box's starter. when a colour light combined with a semaphore might well confuse (although that didn't prevent it being used sometimes).

I had a look through old photos from my onetime 1960s lair, and there's actually, quite by chance, a home/distant combination being returned to danger behind the train and doing exactly this - quarter way down the page, loco 40025 on a railtour :

www.tauntontrains.co.uk



That's the Taunton West Station advanced starter, above the Silk Mill Crossing (1 mile ahead) outer distant/Taunton West Junction inner distant. There was a lot of slotting between boxes here, lots of inners and outers, and every main signal was a home/distant combination.

The GWR didn't do mixed home/distant semaphore and colour-light on one post. I wonder if the distant arms here was returned by power because if it had a balance weight that might have been too much for the electric current available. You would still get the home at danger, and an ATC warning, if it failed to return.

 

[Pigeon]

Would that fail safe? I assume, as with a wire-worked distant, that it ought to revert to caution if it lost power.

The solution they came up with to that one in the early power signalling installation at Crewe was to use not a rotary motor, but a ruddy great solenoid, pulling or not pulling at the arm operating mechanism in exactly the same way as the manual-operation wire does.

It ran off 200V with a pull-in current of 8A and a holding current of 2A. This meant that you would be sucking 400W continuously for every signal you needed to be off, so hand generators were out of the question, and the box of tricks would be gently cooking itself all the time the signal was off. I don't know what they did to get rid of the heat, but it must have been something fairly significant.

You can in fact do the same trick with a rotary motor; the three-way valves in central heating systems do it, but I don't know if it was ever used to work signals. You'd still need continuous power and so not be able to use a hand generator, but you'd need a lot less of it.

 

[matchmaker]

Until Stirling Middle was resignalled with LEDs several years ago, the down distant for the Kincardine line was a motor operated semaphore, slotted with the Down Alloa line semaphore starter (no. 47). Nothing unusual in that at first glance, but the distant was originally Stirling Norths no. 10. When the Kincardine line was reopened, all the signalling as far as Kincardine was converted to LEDs controlled from an NX panel in Stirling Middle. Apart that is from that motor operated semaphore distant. How many semaphore signals have been operated from a modern mosaic style NX panel?

 

[D6130]

Slightly different matter if it was underneath a different box's starter. when a colour light combined with a semaphore might well confuse (although that didn't prevent it being used sometimes).

That arrangement was used extensively by the Southern Railway - and its successor the Southern Region of BR - at locations where there were two boxes close together at the meeting of Absolute Block and Track Circuit Block areas. The pre-1969 up starter signal gantry at Esher (with colour light distants for Hampton Court Junction) was one such instance.

 

[Graham H]

Would that fail safe? I assume, as with a wire-worked distant, that it ought to revert to caution if it lost power.

I'm not really sure why it was worth motorising an isolated semaphore distant. A colour light would probably be cheaper and more reliable, as well as not requiring a fogman (but did the GWR exempt themselves from that on the grounds of having ATC?). Slightly different matter if it was underneath a different box's starter. when a colour light combined with a semaphore might well confuse (although that didn't prevent it being used sometimes).

If you mean a colour light distant below a semaphore starter then yes I am sure the colour light at caution would outshine the starter at red especially at night and thus confuse. I know that at Warblington (Hants) the box there had a colour light distant for Havant below the semaphore starter and in more recent times (and possibly still there) the advance starter at Bognor Regis had a colour light distant below it but what I noticed was that the distant was not lit if the semaphore was not pulled so avoided any confusion that it was just a caution signal. Probably many more examples can be named

 

[D6130]

I know that at Warblington (Hants) the box there had a colour light distant for Havant below the semaphore starter and in more recent times (and possibly still there) the advance starter at Bognor Regis had a colour light distant below it but what I noticed was that the distant was not lit if the semaphore was not pulled so avoided any confusion that it was just a caution signal. Probably many more examples can be named

Yes, this was the normal procedure at Esher and other such locations.

 

[Islineclear3_1]

If you mean a colour light distant below a semaphore starter then yes I am sure the colour light at caution would outshine the starter at red especially at night and thus confuse. I know that at Warblington (Hants) the box there had a colour light distant for Havant below the semaphore starter and in more recent times (and possibly still there) the advance starter at Bognor Regis had a colour light distant below it but what I noticed was that the distant was not lit if the semaphore was not pulled so avoided any confusion that it was just a caution signal.

The one at Bognor is long gone