Quick signal diagram question

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flying scotsman123
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Quick signal diagram question

Postby flying scotsman123 » Mon Jun 06, 2016 8:37 pm

Just a quick question, in idle moments I've been trying to get my head around understanding some signalling diagrams I have for my Stone station project. Here's a picture:

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Now I know that with for example signals 41-44 the lower arm is simply a repeater for the upper arm so if you're close up you're not craning your neck. I presume this is the case for signal 45 but on signals 45 and 46 what do the 2 arms at the same point, with one pointing down denote, and what does it look like in real life?

Thanks in advance. :)
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stuartp
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Re: Quick signal diagram question

Postby stuartp » Mon Jun 06, 2016 10:09 pm

It means that 45 and 46 are 'slotted' by the box off to the left. Before Stone Jcn can accept a train from Colwich there must be 440yds* clear beyond 45 signal, this is the 'clearing point'. Because the junction itself impinges on this and / or there is a short section to the next box to the left, the signalman at Next Box To The Left has a slotted control on Stone Jcn 45 and 46 which he must operate as well as giving a line clear release before 45 and 46 can be cleared. As well as unlocking 45 and 46 the slot will also lock other levers at Next Box To The Left to protect the route through the junction.

The situation doesn't apply on the Norton Bridge line because an outer home (42) has been provided. This is 440yds in rear of 41/44 (it must be otherwise there would be no point in it being there) so the junction is not within the clearing point and the slot is not required.

The signals themselves will look like ordinary co-acting signals, the slotting is done at the base of the post, there are no extra bits of arms to worry about. Not sure what 39 is all about though !

(*Or other distance as specified on the 'box instructions, but usually 440 yards).
Portwilliam - Southwest Scotland in the 1960s, in OO - http://stuart1968.wordpress.com/

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flying scotsman123
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Re: Quick signal diagram question

Postby flying scotsman123 » Mon Jun 06, 2016 10:48 pm

Excellent, thanks for that Stuart, in other words then, as far as modelling is concerned, I can treat it as a usual signal. I meant to add, how would things be different if there was a trailing crossover on the Colwich lines just at the right hand end of the platforms?

As for 39, no idea, but I can't seem to make it out on my britain from above picture which was taken in 1929, so perhaps a knotty oddity that the LMS soon dispensed with? They changed the rest of the signalling at some point between 1929 and 1950, which looks like it entailed replacing all the posts with LMS ones dispensing with the lower co-repeater signals.

Edit - just had a quick flick through one of my reference books, which talks about backing signals, consisted of a cutout B. This was 3ft 4in high and 2ft wide. It was mounted on a post with the lamp on top, which revolved through 90 degrees, in a similar way to the ground discs. All NSR signalling was Mckenzie and Holland by the way.
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stuartp
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Re: Quick signal diagram question

Postby stuartp » Tue Jun 07, 2016 2:01 am

"Backing" makes sense, that meant different things on different railways but usually a signalled wrong direction movement. Wrong direction towards 44 would be my guess, and accounts for 44 being there too.

Provided the crossover was inside (i.e. protected by) 45 I don't see a problem, there would be a couple of ground signals for movements through it. You would almost certainly need a starter towards Colwich, otherwise there's nothing to stop a movement in that direction. You could make it a lot more complicated too there are always several different ways to signal any given location. The NER, for example, would be wondering where all the other signals had gone.
Portwilliam - Southwest Scotland in the 1960s, in OO - http://stuart1968.wordpress.com/

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pointstaken
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Re: Quick signal diagram question

Postby pointstaken » Thu Jun 09, 2016 12:42 pm

My Model railway (when it's built) will be an American industrial line, but I find these discussion on British signalling informative and interesting. Thanks fellas for the information and detail.

Dennis
I know nothing, but much I believe

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flying scotsman123
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Re: Quick signal diagram question

Postby flying scotsman123 » Thu Jun 09, 2016 1:05 pm

I'm very slowly getting to grips with signalling, helped by my volunteer work on the GWSR - you can read as much as you like but is' much easier, more interesting and fun to go down to you're local heritage railway and observe movements!
"listen carefully, i shall say this only once"

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