GWR BLT signalling - ground discs at foot of home signal and/or dependant discs?

[The Great Bear]

Having made some progress with the signals (see layout thread), I will shortly be bodging together the three disc stack. But that got me wondering about operation and these signals...

 

There's a gap between the home signal and the first point into the back siding. Small in the real world scheme of things, bigish in this little model - well a couple of wagon lengths. When shunting to see the disc the whole train would have to move forward (or the shunter walk) to infront of the home signal then move back, is that right? Or would this not matter so much, the shunter looks at the point blades and once set directs the train back?

 

Who's in charge when shunting, the shunter (?) is he directing with hand signals both the driver and the signalman?

 

Alternatively (and I thought I'd ask before cobbling together something bespoke), if a train is never intended to directly enter the two sidings - as the loco would need to run aound first - could the discs be at the toe of the points or is that an absolute no no as they are a facing move on a passenger line?

 

Hopefully the questions make sense!

 

Thanks

 

Jon

[The Stationmaster]

The question makes perfect(ly bloomin' awkward) sense. Put the disc by the Home Signal and we'll assume there's a track circuit there (unless you've stuck in some dummy point locking bars in the meanwhile?).

 

The Shunter is in charge of shunting movements (or it could be a Guard acting as Shunter of course) - the Signalman works to what the Shunter wants and the Driver does what the Shunter tells him to do - be it verbally or by means of handsignals (in their various forms such as using arms & hands, or a lamp or a whistle).

[The Great Bear]

Put the disc by the Home Signal and we'll assume there's a track circuit there (unless you've stuck in some dummy point locking bars in the meanwhile?).

 

Thanks Mike, but I'm afraid you're going to have to explain this one further as not sure I understand. The "locking bar" isn't the facing point lock itself, is it but something related. http://85a.co.uk/for...=721&forum_id=1 especially no.13 helps a bit. From this if I understnad correctly, the locking bar stops the points being moved with something on them? Is it that the track circuit is tied to the points so that if there's something in that section of line, there is some electical linkage to the lever frame? But what would the sections be, because there could be odd wagons standing during shunting say adjacent to the box.

[The Stationmaster]

Thanks Mike, but I'm afraid you're going to have to explain this one further as not sure I understand. The "locking bar" isn't the facing point lock itself, is it but something related. http://85a.co.uk/for...=721&forum_id=1 especially no.13 helps a bit. From this if I understnad correctly, the locking bar stops the points being moved with something on them? Is it that the track circuit is tied to the points so that if there's something in that section of line, there is some electical linkage to the lever frame? But what would the sections be, because there could be odd wagons standing during shunting say adjacent to the box.

Jon, Looks like you understand far more than you credit yourself with . Micknich's two posts in that thread explain and illustrate the principle of the Facing Point Locking Bar very well and its purpose was indeed to prevent points being moved when something was on them or once it had passed the protecting signal at a facing point but had not reached the point itself. The idea of the latter feature was to prevent a Signalman moving the points once the signal had been returned to danger (irregularly returned to danger to be precise).

 

The track circuit does exactly the same but electrically instead of mechanically - if the track is occupied an electric lock on the Facing Point Lock lever (in Western practice the lock is on the FPL lever) prevents the points from being unlocked when vehicles are standing on the points. In your case the track circuit would go through both facing points (and hardly any distance beyond them) so if the FPL lever is standing reverse (=locked) it could not be moved if the track is occupied.

 

Now if you are shunting there is a simple way round this but don't go telling anybody on the 'big railway' please - you simply don't bother to reverse the FPL lever to lock the points so the points can be changed at will (and with care of course). The running signals won't be able to be cleared unless the FPL lever is reversed but the discs will (and I won't be telling you where I got the tee shirt but rest assured it was not on 'the national network' as we now have to call it ).

[The Great Bear]

Now if you are shunting there is a simple way round this but don't go telling anybody on the 'big railway' please - you simply don't bother to reverse the FPL lever to lock the points so the points can be changed at will (and with care of course). The running signals won't be able to be cleared unless the FPL lever is reversed but the discs will (and I won't be telling you where I got the tee shirt but rest assured it was not on 'the national network' as we now have to call it ).

 

OK thanks, Mike. So proper procedure would require the loco to pull forward such that the last wagon was clear of the first facing point, but for expediency I could do what is rumoured to have been done on a full sized train set once upon a time. Given that the former would required the train moving off scene more, the latter approach appeals, and smile at living life on the edge. When my modelling gets onto the mainline I'll have to be more careful to go by the book!

[The Great Bear]

One final (hopefully!) question, if I may: would the disc stack be right next to the tie-bar of the first point or would it be adjacent to the base of the signal post which is small distance in advance (an inch or so in the model) or could it be either? From a clearance point of view on my layout and also visibility of the discs, the latter would be better. (Would there be any direct linkage between the discs and the points or is that all done in the locking room?)

 

Thanks

 

Jon

[The Stationmaster]

One final (hopefully!) question, if I may: would the disc stack be right next to the tie-bar of the first point or would it be adjacent to the base of the signal post which is small distance in advance (an inch or so in the model) or could it be either? From a clearance point of view on my layout and also visibility of the discs, the latter would be better. (Would there be any direct linkage between the discs and the points or is that all done in the locking room?)

Thanks

Jon

The disc stack (what a lovely term, I like it ) would be immediately adjacent to the main signal as a disc 'off' would be the authority to pass that signal (earlier practice was a bit different, typical GWR).

The operating wires to the discs would usually be run through detectors at the points to ensure the pouints are correctly set before the disc can be cleared. However Western practice was to not detect points for disc signals if the point had a facing point lock so in this case the wires would run straight to the signal from the signalbox.

 

Incidentally the signal s are in rear of the point toe. The terms 'in advance' and 'in rear' are extremely simple concepts to grasp if decently explained so I'll try to do exactly that. If you imagine you are standing on a railway line looking in the direction of travel everything you see is in advance of you, and - perhaps you need to tap it to confirm - everything behind you is 'in rear' of you. Easy when applied to a double line, no different when applied to a train - what it is heading towards is 'in advance' and what is behind it is 'in rear'. If the train reverses then we simply turn round 'in advance' and 'in rear'. If we are talking about a single line thw terms are used in direct relationship to the direction a train is to move or the way in which we talk of successive objects; think of 3 stations as A, B, & C - a train is heading away from A towards B & C, thus they are in advance and A is in rear. If the train was heading towards A it would be in advance and, assuming it had passed B - it would be 'in rear'.

 

Simple and utterly unambiguous - in fact so simple it is now virtually eliminated from the the RSSB Rule Book because it has been turned into meaningless, and in places dangerously ambiguous. so called 'plain English' (even if 'Faraway Signal' didn't make it as replacement for 'Distant Signal').

[The Great Bear]

Once again thank you for the reponse on the discs and enlightening me on terminology - very clearly explained and makes perfect sense.

 

Thanks

 

Jon

[The Great Bear]

Thanks. That confers with what I was told by someone who was very senior in BR of old: stations will need to be fully compliant with the requirments that were in force when they were last signalled, and in theory with major legislation, e.g. lock, block and brake acts - although even there, Ashburton fell under the BoT radar!

 

To return to the OPs plan, this suggests a simpler possibility, with point discs in place of those operated by levers 7,10 and 13, and no requirement at all for discs numbers 2,3 and 4. Personally, I would have the home operated by lever 2, with lever 1 white or even an empty space, reflecting the fact that the distant was once operable. If your advance starting signal is for entry into the block section, then you do not have to have a starter as well: signal 16 can serve this function, though I would put the subsidiary arm at number 15 before it. I would also say that the ground frame release might be a simple point lever, or if the platform stopped short of the points, then a hand lever. How far away from the main points is thje road bridge? Should the home be the other side of it? And if so, would there be a calling-on or similar signal for shunting moves, as the loco would be poorly sighted to see any hand signals?

 

However, from a singalling perspective, the layout is identical to Watlington, other than points 9 and facing point lock 8, so there is a prototype there which can be used to inspire the signalling here.

 

Addendum (edit):

 

So, it could be:

 

1: Spare (was distant)

2: Home signal

3: Calling on

4: FPL for number 6 points

5: Points to loop

6: FPL for number 7 points

7: Points to back siding

8: FPL for number 9 points

9: Points to goods shed

10: Spare

11: Loco release points or ground frame release

12: Spare

13: Shunt ahead signal

14: Starting signal

 

I have put in the extra spares as this is the size of the MSE kit, but you could also use number 10 to operate the other goods yard points and 12 to operate the creamery points.

 

Just some thoughts: it all depends on the presumed traffic levels, and the date of construction/most recent alterations.

 

 

 

 

Seems an odd mixture of things from different periods to be honest. For instance if you're still in the time of point discs why has a Calling On been added at a low number in the frame which could probably have meant altering and renumbering the rest but clinging to older practices at the same time. And I can't understand what you have done with the platform starting signal - that was one which, if most other things were lacking, was almost invariably provided; so to leave it out of the simplified signalling would be quite unusual - it was the one (on a full locking frame) which proved the road was set for a departing passenger train. I'm also puzzled by your comment about using a Calling On signal for shunting - the only purpose it would serve is to admit a movement to the already occupied platform line; the way to signal shunting moves is to provide a co-located disc or discs, which sort of takes us round in a circle to where we were not so long ago.

 

I'd like to have working signals on the layout (and test DCC conceptss Cobalt-S levers), sometheing to get things moving again after period of hibernation and also entertain whilst doing scenic stuff on the mainline.

 

Operational ground discs (especially the stacked one) will be beyond me, I think. Could I adopt something like Simon's suggestion, noting Mike's comments ie keep the starter, advance starter (without the shunt arm possibly) and home, with the other moves (where ground discs were) controlled by hand signals as they'd only be used during shunting?

 

Thanks, Jon

 

 

 

 

 

[The Stationmaster]

I'd like to have working signals on the layout (and test DCC conceptss Cobalt-S levers), sometheing to get things moving again after period of hibernation and also entertain whilst doing scenic stuff on the mainline.

 

Operational ground discs (especially the stacked one) will be beyond me, I think. Could I adopt something like Simon's suggestion, noting Mike's comments ie keep the starter, advance starter (without the shunt arm possibly) and home, with the other moves (where ground discs were) controlled by hand signals as they'd only be used during shunting?

 

Thanks, Jon

 

 

 

 

Jon, I would be inclined to include the ground discs and accept the fact that they don't work.  I suspect working ones would be beyond me although I know full well - and have seen - the excellent 2mm scales ones produced by Missy of this parish, and they do work (yes, I did say 2mm scale).

 

Wallingford of course was not a block post and the branch was worked on the 'One Engine In Steam' principle and while the building might well have born a nameplate that included the word 'signalbox' technically it wasn't as it had no block telegraph (certainly by 1938).  It was also clearly arranged as a ground frame - indeed noticeably so in the latter context from the lack of running line signals to protect the points immediately adjacent to the lever frame.  The possibility that lever No.1 had once operated a worked Distant Signal harks back to very old practice (as far as the GWR was concerned) suggesting the lever frame dates from the 19th century as the GWr was using fixed distants approaching minor termini by the early years of the 20th century, if not earlier.

[The Great Bear]

Thanks, Mike. Thanks for the info on Wallingford - that's the inspiration for the BLT. Whilst for a small branch line like mine a ground frame more typical (the other inspiration the Woodstock branch worked on one engine in steam basis since 1920s), the signal box has the advantage that should I have visitors we could try using bell to add to the realism. Plus I had already detailed the signal box on that basis.

 

I'll see how I get on motorising the Ratio signals. If that goes ok (haven't high hopes) then who knows maybe I'll try a single ground disc - I could live without moving balance arm.

 

Ta

 

Jon

[The Great Bear]

 

To simplify wiring up levers and because some signals I've damaged, contrary to the above I've decided that my branch will operate One Engine In Steam and so have rationalised signalling, only have a home and a starter signal and no ground discs and box be a ground frame. This better matches prototypes used for inspiration.

 

I am trying to work out if I can interlock signals and points electronically using the extra contacts on the DCC concepts switches, Would the two signals be interlocked, so they only could be off when the route to and from the platform line was set? Not sure I can achieve this, so would this have been a necessity in reality?

 

 

[The Stationmaster]

Marlingford Box Signalling Diagram-Model.jpg

 

To simplify wiring up levers and because some signals I've damaged, contrary to the above I've decided that my branch will operate One Engine In Steam and so have rationalised signalling, only have a home and a starter signal and no ground discs and box be a ground frame. This better matches prototypes used for inspiration.

 

I am trying to work out if I can interlock signals and points electronically using the extra contacts on the DCC concepts switches, Would the two signals be interlocked, so they only could be off when the route to and from the platform line was set? Not sure I can achieve this, so would this have been a necessity in reality?

You have a slight problem in that you are finishing up with a ground frame working unsignalled points which are not immediately next to it - which technically was illegal (and in effect still is)  and which was not the case at Wallingford, as can be seen in the small scale view of it in the link here -

http://www.s-r-s.org.uk/html/gwa/S174.htm

 

 

But it's your railway

 

As far as the electronic locking on what you propose to do the locking would be as follows - 

To clear signal No. 1 would require levers 3, 5, and 6 standing normal and levers 2 and 4 standing reverse.  It is likely that signals 1 & 2 would also lock each other.

To clear signal No. 2 would require levers 3, 5, and 6 standing normal.

 

I would be very surprised indeed if the signals were not interlocked with the relevant points - that was a requirement under the 1889 Regulation of Railways Act and although taht Act is no longer on the statute book it was there until the early years of this century.

[The Great Bear]

You have a slight problem in that you are finishing up with a ground frame working unsignalled points which are not immediately next to it - which technically was illegal (and in effect still is)  and which was not the case at Wallingford, as can be seen in the small scale view of it in the link here -

http://www.s-r-s.org.uk/html/gwa/S174.htm

 

 

 

Mike, thanks for the reply. Looking at a larger version of the plan and also photo, there doesn't appear to be a signal controlling the entry in to the loop by the home signal; quite a long distance in case of Wallingford. Looks like an anomaly I could ape to suit my purposes! (That's the It's My Railway bit )

 

Trying to do all that interlocking will be a challenge.

 

Thanks again for your help,

 

Jon

[The Stationmaster]

Mike, thanks for the reply. Looking at a larger version of the plan and also photo, there doesn't appear to be a signal controlling the entry in to the loop by the home signal; quite a long distance in case of Wallingford. Looks like an anomaly I could ape to suit my purposes! (That's the It's My Railway bit )

 

Trying to do all that interlocking will be a challenge.

 

Thanks again for your help,

 

Jon

I suspect Jon - and I could be wrong - that the only movements which usually took place there (or were supposed to take place there) were out of the loop rather than into it from the Main line (yes folks without the benefit of the plan, it was indeed called the 'Main Line').  The logical method of working would be for a train that required to run round or shunt the goods yard to stop on the main and run-round then propel into the platform and back into the loop to shunt the yard - and a couple of the pics in PK's book on the branch tend to suggest that shunting was carried out in this way/off the loop.

 

Edit to add PS - not sure how you're going to use your various switches/levers Jon but the interlocking I suggested is very easy if done electrically and provided you accept that the lever itself is not locked.  You simply feed the returns from the signal motors through a contact on each of the levers I mentioned as releasing the signal - thus the signal won't come off unless there is a complete return path through all the relevant lever contacts.  More a sort of locking by exception than doing it a positive way but it should work.

[RailWest]

"However Western practice was to not detect points for disc signals if the point had a facing point lock

...."

 

But presumably only if there was a 2-hole stretcher so that the FPL locked for the diverging route for which the disc applied???

[The Stationmaster]

"However Western practice was to not detect points for disc signals if the point had a facing point lock

...."

 

But presumably only if there was a 2-hole stretcher so that the FPL locked for the diverging route for which the disc applied???

I believe so - from the way John Madeley explained it to me (and the way we decided to omit some detection as a result at Tyseley museum) the principle was that as long as the route could be bolted there was no need to detect discs.

[The Great Bear]

Edit to add PS - not sure how you're going to use your various switches/levers Jon but the interlocking I suggested is very easy if done electrically and provided you accept that the lever itself is not locked.  You simply feed the returns from the signal motors through a contact on each of the levers I mentioned as releasing the signal - thus the signal won't come off unless there is a complete return path through all the relevant lever contacts.  More a sort of locking by exception than doing it a positive way but it should work.

 

Thanks, Mike

 

Almost got this sorted, facing point locks, ground frame release and home signal with interlocking done - a motorised Ratio one driven by servo - but the starter - a Dapol one - the same approach doesn't seem to work: a function of the way the signal works, perhaps? (No electical expert, me)

[The Stationmaster]

Thanks, Mike

 

Almost got this sorted, facing point locks, ground frame release and home signal with interlocking done - a motorised Ratio one driven by servo - but the starter - a Dapol one - the same approach doesn't seem to work: a function of the way the signal works, perhaps? (No electical expert, me)

It is a function of the way the Dapol signal works (or isn't worked to be more correct) because it only needs a brief make of a contact to move the arm in either direction.  What I would therefore suggest - as it's impossible to fully interlock it due to that mode of operation - is to provide a totally separate spring loaded push to make pushbutton switch which you push to change the signal arm from whatever state it happens to be in (i.e. wire as per Dapol instructions) because if you try to interlock it through simple contacts it could be locked in either position inadvertently or unintentionally.  If that doesn't suit you go searching on here for the thread about converting Dapol signals to an on/off form of powering the solenoid - alas I can't remember what that thread is called.

[The Great Bear]

Nearly a couple of years on, crikey time flies, motorised ground signals I can manage so am thinking again about this. Would single white discs (white light on running line, red on sidings/loop) adjacent to each point be ok? Strikes me as much same way signals on the branch at my mainline station are done.

 

To recycle a couple of levers for this I'd change the release crossover to be under direct control of the box(main ground frame)

 

Thanks

 

Jon

[The Stationmaster]

Nearly a couple of years on, crikey time flies, motorised ground signals I can manage so am thinking again about this. Would single white discs (white light on running line, red on sidings/loop) adjacent to each point be ok? Strikes me as much same way signals on the branch at my mainline station are done.

 

To recycle a couple of levers for this I'd change the release crossover to be under direct control of the box(main ground frame)

 

Thanks

 

Jon

Is this for the junction or the branch terminus Jon?

[The Great Bear]

Is this for the junction or the branch terminus Jon?

The branch terminus, Mike. Single discs is as complex as I'd like, if that's feasible. Thanks, Jon

[The Stationmaster]

Well you could go the way you were before Jon - with no discs at all - and it could easily be justified if you wish.  But, as you are getting the ground signal bit between your teeth - read on.
 

You could have a co-located disc by the Home Signal to read through points 3b reverse.  You could also have discs at 3a, 5a and 5b,

 

The problem comes with 5b and 6b because as far as I can traced white light signals (discs and backing signals) were never used for facing running movements.  They would either be red light discs which could be pulled with the points in either position or quite likely small arm signals as part of the signal structure at the Home signal (and all too typical in that sort of arrangement as it happens) so maybe you could do it that way?  The alternative is doing it with red light discs at 5b and 6b and assuming the lever frame was renewed with tappet locking in the 1930s.

 

I suspect it might be harder to find examples with discs at =5b & 6b than it would be to find small arms reading into the sidings.

[The Great Bear]

Well you could go the way you were before Jon - with no discs at all - and it could easily be justified if you wish.  But, as you are getting the ground signal bit between your teeth - read on.

 

You could have a co-located disc by the Home Signal to read through points 3b reverse.  You could also have discs at 3a, 5a and 5b,

 

The problem comes with 5b and 6b because as far as I can traced white light signals (discs and backing signals) were never used for facing running movements.  They would either be red light discs which could be pulled with the points in either position or quite likely small arm signals as part of the signal structure at the Home signal (and all too typical in that sort of arrangement as it happens) so maybe you could do it that way?  The alternative is doing it with red light discs at 5b and 6b and assuming the lever frame was renewed with tappet locking in the 1930s.

 

I suspect it might be harder to find examples with discs at =5b & 6b than it would be to find small arms reading into the sidings.

A lot to be said for leaving as is, fixing damage from the branch being mothballed under my mess and get trains running rather than create more damage!

 

With regard to white light discs on running lines, weren't some at Kidlington (=Begbrooke) just that? Certainly that's what I've done with ones at either end of branch run around loop and the one leading into the yard; in that for straight on moves they can be passed at danger and off when the diverging route set. Think we discussed that in the signalling thread for Begbrooke or have I misunderstood. (Quite possible, in which case tiny dabs of clear red paint in order!)

[The Stationmaster]

A lot to be said for leaving as is, fixing damage from the branch being mothballed under my mess and get trains running rather than create more damage!

 

With regard to white light discs on running lines, weren't some at Kidlington (=Begbrooke) just that? Certainly that's what I've done with ones at either end of branch run around loop and the one leading into the yard; in that for straight on moves they can be passed at danger and off when the diverging route set. Think we discussed that in the signalling thread for Begbrooke or have I misunderstood. (Quite possible, in which case tiny dabs of clear red paint in order!)

If they're co-located with a (stop) running signal they should normally have a red light,  stop blocks end of the runround the one on the platform line should have a red light.  The one leading into the yard is 'interesting' - looks like something to revisit sometime but I suspect we are talking about a slightly different situation.