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Interpreting a S-R-S signal box diagram (Helston)


James Parker
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I am struggling to interpret just one element of the signal box diagram produced by the signalling record society for Helston (GWR).  The diagram is here https://www.s-r-s.org.uk/html/gwf/S1195.htm (I wont copy it in case of breach of copyright).

The turnout which connects the engine loop and the siding (on the left hand side of the diagram) doesn't show a  'normal' position, isn't labelled 'sprung' and doesn't have a corresponding lever in the box.  I cant find any evidence in photos of a ground frame nor any reference to one.  So the question is, how was this turnout (and shunting operations in general) worked, particularly in the 1956 layout.  Its clear how you get (or rather a train gets) to the engine loop but not how the train gets to the siding, goods shed and places beyond.  Do I have to infer a ground frame or is there some mechanism, depicted by the symbol which appears on this diagram only for one turnout, which indicates some other means of operation?

'Signal Box Diagrams of the Great Western and Southern Railways (Pryor) has exactly the same symbology but equally no explanation.  Doubtless this is therefore obvious to those with a good knowledge of prototype working practice, but sadly not to me.

In reality on my (very, very slowly emerging) model, the turnout does of course have a point servo, so I can do what I want, but I'm keen to understand how the prototype would have been worked.

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The only photo that I can find of the south end of the station possibly shows a hand level for one of these points. It is not a clear photo as there is a van in the way. 

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The symbol on the diagram indicates a hand-operated turnout, so a lever or the like adjacent to it. So far as the signaling system is concerned, its status is unknown, it could have been thrown either way; its not under the control of the signalman.

 

 

 

 

 

 

Edited by Nearholmer
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A Nearholmer rightly states, it's hand operated. On signal diagrams (of whatever region/company), any turnout which doesn't show its status with a small perpendicular dash through it will be hand worked. Also remember that signalling layouts are just that - they show the signalling. Often there will be sidings and other bits of track which are not shown, as they'll be beyond the area under control of the signalman. 

Oh, and the dash before a turnout (such as the one under the bridge and on platform line by the bracket signal), indicate a facing point lock for that turnout.

Edited by Peter Kazmierczak
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6 minutes ago, Peter Kazmierczak said:

Oh, and the dash before a turnout (such as the one under the bridge and on platform line by the bracket signal), indicate a facing point lock for that turnout.

 

Isn't there also a symbol that looks a bit like lower case 't' across the open switch, which also indicates an FPL, but without a fouling bar? Used where a track circuit deals with a train over the point, but also ......... here I trail off, because I've forgotten the other circumstances where it applies.

 

Perhaps a "proper signaling person" could start a thread explaining all the symbols.

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The symbols at the beginning of the Pryer books don't show the symbol for a hand point but they do show the manner in which a point worked from a lever frame is drawn.  So by inference, (even without knowledge of the symbol which is used) that point is not worked from a lever frame (nor is it labelled as a spring point) so the only thing that it could be is a hand point.

 

The hand lever on that point is readily visible in two photos (the one labelled '1920', and particularly clearly in the one labelled '1948') on the site linked below and is also just about visible in a couple of the other photos

 

http://www.rosewarnejunction.me.uk/helston-station-history/

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1 hour ago, Nearholmer said:

 

Isn't there also a symbol that looks a bit like lower case 't' across the open switch, which also indicates an FPL, but without a fouling bar? Used where a track circuit deals with a train over the point, but also ......... here I trail off, because I've forgotten the other circumstances where it applies.

 

Perhaps a "proper signaling person" could start a thread explaining all the symbols.

The 't' like symbol indicates a point which has a facing point lock, if there is also a facing point lock(ing) bar it is indicated by a small line drawn separately from the switch and FPL symbols.  BS 376 Part 1 (1954 edition is a good reference but they are uncanged in the 2012 edition) shows these symbols and they were also included in the diagram of standard railway sketching symbols in the 1960 and 1972 editions of the BR General Appendix.

 

The hand point symbol was not included in the General Appendix but is in Part 1 of BS 376.

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6 hours ago, The Stationmaster said:

The 't' like symbol indicates a point which has a facing point lock, if there is also a facing point lock(ing) bar it is indicated by a small line drawn separately from the switch and FPL symbols


Except that, on some (many?) drawings, the ‘t’ seems to be omitted, the presence of the FPL being implied by the presence of the bar.

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Thanks for all the info and particularly pointing out the 1948 picture, somehow Id missed the lever.

 

It seems a bit odd still, just beyond ('up' the line) is a signalman controlled catch point.  I estimate there is enough space for a loco and maybe one waggon between the hand operated point and the catch point.  So, as far as I can work out, any reasonable shunting operation will require the signalman to close the catch point and most likely activate the shunt ahead signal on the main line, effectively forcing the main line to be handed over to the engine crew for the duration of the shunting., whereas had one of the sprung points been hand operated instead, shunting could take place entirely within the yard. 

 

I think Im showing my ignorance of prototype working practice here!

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30 minutes ago, James Parker said:

It seems a bit odd still, just beyond ('up' the line) is a signalman controlled catch point.  I estimate there is enough space for a loco and maybe one waggon between the hand operated point and the catch point.  So, as far as I can work out, any reasonable shunting operation will require the signalman to close the catch point and most likely activate the shunt ahead signal on the main line, effectively forcing the main line to be handed over to the engine crew for the duration of the shunting., whereas had one of the sprung points been hand operated instead, shunting could take place entirely within the yard. 

 

I don't know the operating practice on the line, but I doubt if the Helston branch had a particularly intensive service.  Therefore I'm assuming that goods shunting on the mainline would not obstruct any passenger service and there was no need to separate it by providing a headshunt.  

We need to remember that in terms of train movement, a station such as this would see fairly short periods of operation, followed by a long time with nothing happening.

Hope this helps,

Dave.

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My surmise is that shunting by loco here was pretty simple, and didn't take too long: pull out everything that was to depart, and put it in the engine loop, being careful not to get tangled-up in the spring points; divide the incoming into two cuts, one for the loading dock road, one for the goods-shed road, possibly sorting the order of things in the process, and pop those into respective roads; form-up ready to leave.

 

The goods shed road has enough room to allow wagons to be filtered through the shed a couple at a time by manual/horse shunting - it might even be on a handy gradient towards the stops to allow gravitation. And, the over-run towards The Lizard gives a good place to store wagons that have been dealt with in the goods shed until departure.

 

That, combined with a sparse passenger service as mentioned by DLT obviates the nead for a head-shunt.

 

 

Edited by Nearholmer
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Postwar - using the 1947 STT as an example - the Helston branch, rather unusually had two Down freight trips during the day but the passenger service was so infrequent that there was masses of tome available to shunt.  The Morning trip was booked to arrive at 08.30 and the following passenger train didn't leave Nancegollan until 08.54 so the freight had bags of time to run round and get some shunting done before the passenger train arrived at 09.05.  after the passenger train had left there wasn't another train - a Down passenger treain - for almost an hour so masses of time to get inwards traffic shunted and the yard squared up.  The second freight trip only spent 20 minutes at Helston so basically probably did little more than clear whatever ards traffic was available plus empties.

 

Although photos indicate the place was probably fairly busy in freight traffic terms it was hardly difficult to shunt and the short distance between the trap point and the handpoint would be irrelevant as obviously any shunts between the engine loop and the goods shed road would need to go beyond the trap in any event.  In fact the 1959 retention, when the lever frame was renewed, of the Shunt Ahead subsidiary below the Advanced Starting Signal clearly indicates that there was a regular need to pass that signal when shunting.   The thing which strikes me as a bit odd - probably driven by the siting of the trap points for both sidings - was the fact that the point leading to the other siding was worked from the signal box (lever No.8 until 1959, thence lever No.7) which was no doubt far from popular with the Signalmen as it meant them pulling for shunting moves to that siding - but equally it gave them something to do in an otherwise fairly quiet job.  But never the less an arrangement like that, with a the Signalman pulling what amounted to yard points for shunting moves, was both time consuming and a nice recipe for a derailment had it been at a much busier place.

 

As already pointed out most branch lines were pretty quiet in the past and passenger train services tended to be somewhat intermittent which left plenty of time to deal with freight trips so shunting out onto the branch running line was commonplace.  Many railway modellers tend, I suspect, to think in terms of far more frequent passenger train services than was commonly the case.  Helston in the 1952 winter timetable had only 9 passenger train arrivals and 8 departures daily (and no Sunday service) with, in several instances, gaps of c.2 hours between successive trains in either direction - it was a quiet line in passenger traffic terms.

 

5 hours ago, James Parker said:

Thanks for all the info and particularly pointing out the 1948 picture, somehow Id missed the lever.

 

It seems a bit odd still, just beyond ('up' the line) is a signalman controlled catch point.  I estimate there is enough space for a loco and maybe one waggon between the hand operated point and the catch point.  So, as far as I can work out, any reasonable shunting operation will require the signalman to close the catch point and most likely activate the shunt ahead signal on the main line, effectively forcing the main line to be handed over to the engine crew for the duration of the shunting., whereas had one of the sprung points been hand operated instead, shunting could take place entirely within the yard. 

 

I think Im showing my ignorance of prototype working practice here!

I'm not sure what point (sorry) you are making about the spring points and shunting entirely with the yard?   The engine would have to shunt the freight and Mixed Trains from the signal box end of the layout in order not to get boxed-in,  the only possible advantage of shunting over the spring point would be if the morning trip arrived with traffic for the goods shed on the engine and the train ran to the engine loop - from which it could easily be shunted to that end of the goods shed.  But it could just as easily be shunted, albeit with an extra dog-leg in the moves, from the platform line to that end of the goods shed.   But the engine still needs to get to the signal box end of the train in order to shunt the rest of the yard/inwards traffic.

 

In any event the spring point at the end of the goods shed road would almost certainly have had a 'hold down' lever to enable a facing movement tp be made through it in the direction it was normally sprung against.  In fact on the page I linked previously there is a photo of that point, supposedly taken 'towards the end of the branch line's operation' with a normal two way handpoint  lever and lying set away from the goods shed road.  The photo raises another question because apart from the point lever rather oddly compared with George Pryer's drawings there is a non-independent point indicator adjacent to the engine release point in the platform and clearly applicable to a facing movement through the release points (which appear to be set towards the loop).  This would appear to reflect the arrangement prior to 1959 although it is shown in a strange way on George's drawing.  Like any human George, as he said to me on one occasion when we met to look at some training equipment, was not infallible and he had v become aware of minor errors on one or two of his 'box diagram drawings although I hadn't seen this one back then so couldn't query it with him.  However what I suspect is that the ground disc (No7) and the point indicator (labelled P.D.) in the 1945 drawing had somehow become transposed. That in turn dates the photo as being prior to 1959, notwithstanding the weeds and dereliction because No.8 in the 1959 frame was very definitely locked as a worked signal.  Something we need more photos to analyse - one way or the other.  And possibly the redundant point indicator wasn't removed after the 1959 changes?.

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Thanks for all the answers, it makes me realise how much I don't know.

 

There is a story for Helston (on the Helston branch website I think) that one technique for running round passenger stock, when the run round loop was full with wagons, was to push the coaches back out of the station up the incline, put the brake on, withdraw the loco into the loco shed and then let the coaches run down the hill back into the station under gravity controlling them with the brake.  The engine could then simply be reversed out of the loco shed onto the front of the coaches.  Presumably this was done, if at all, without passengers onboard.

 

Its a great story, I have no idea if its true, and nor have I any idea how to model it (in 2mm finescale) other than the obvious one of building a coach with a fully driven bogie, which seems a bit excessive.  It would make a nice trick for a model though!

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18 hours ago, James Parker said:

Thanks for all the answers, it makes me realise how much I don't know.

 

There is a story for Helston (on the Helston branch website I think) that one technique for running round passenger stock, when the run round loop was full with wagons, was to push the coaches back out of the station up the incline, put the brake on, withdraw the loco into the loco shed and then let the coaches run down the hill back into the station under gravity controlling them with the brake.  The engine could then simply be reversed out of the loco shed onto the front of the coaches.  Presumably this was done, if at all, without passengers onboard.

 

Its a great story, I have no idea if its true, and nor have I any idea how to model it (in 2mm finescale) other than the obvious one of building a coach with a fully driven bogie, which seems a bit excessive.  It would make a nice trick for a model though!

The gradient approaching Helston was such that gravitation of coaches to enable the engine to get on the other end looks to have been perfectly feasible.  Method would be the usual way of doing such a job - train arrives and passengers alight and any brakevan traffic would be unloaded.  The engine would then propel the stock back to what had no doubt been identified as the ideal spot from which the coaches could roll; the Guard's handbrake would be very firmly applied;  and the engine would make its way to shed or whatever siding was convenient.  once the engine was out of the way the Guard would release the handbrake and let the coaches roll using the brake setter to apply the vacuum brake to the required degree in the normal place to bring the coaches to a stand exactly where they were required to halt.  

 

Simple process, not really unusual although it might have been used as a shortcut rather than an authorised method at Helston.  And perfectly safe in the hands of experienced staff especially at a place like Helston with plenty of room if the braking went a bit awry..  Modelling it? - u you would have to use a motorised coach as you suggested

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7 hours ago, The Stationmaster said:

Simple process, not really unusual although it might have been used as a shortcut rather than an authorised method at Helston.  And perfectly safe in the hands of experienced staff especially at a place like Helston with plenty of room if the braking went a bit awry..  Modelling it? - u you would have to use a motorised coach as you suggested

Not necessarily, though I agree under DCC that would be the easiest way, and it wouldn't be very difficult to do under DC either.   Can't help thinking somebody should produce a DCC-ready motorised slip coach.

 

You could model it under gravity.  You would need some device to hold carriage in place after uncoupling whilst you ran the loco clear.  That could be a solenoid-worked hook arrangement in the 4-foot.  It might even be possible to do it using a powerful electromagnet under the baseboard?  The position of the device would be determined by trial and error just using your finger to identify the ideal release point.

 

Only place I have heard of that definitely did it officially was Banff.

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12 hours ago, Michael Hodgson said:

Not necessarily, though I agree under DCC that would be the easiest way, and it wouldn't be very difficult to do under DC either.   Can't help thinking somebody should produce a DCC-ready motorised slip coach.

 

You could model it under gravity.  You would need some device to hold carriage in place after uncoupling whilst you ran the loco clear.  That could be a solenoid-worked hook arrangement in the 4-foot.  It might even be possible to do it using a powerful electromagnet under the baseboard?  The position of the device would be determined by trial and error just using your finger to identify the ideal release point.

 

Only place I have heard of that definitely did it officially was Banff.

I do wonder if a coach, especially in 2mm scale, would have sufficient mass to roll for the needed distance, and stop in the right place?  Hence why I suggested motorisation.

 

Gravitation of the coaching stock was officially used to 'run round' at Maiden Newton (for the Bridport branch train) and also at Yelverton for the Princetown branch train.  It might well have been used elsewhere as it was a safe and simple process if carried out correctly.

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56 minutes ago, The Stationmaster said:

I do wonder if a coach, especially in 2mm scale, would have sufficient mass to roll for the needed distance, and stop in the right place?  Hence why I suggested motorisation.

 

Gravitation of the coaching stock was officially used to 'run round' at Maiden Newton (for the Bridport branch train) and also at Yelverton for the Princetown branch train.  It might well have been used elsewhere as it was a safe and simple process if carried out correctly.

Surely that depends on the gradient, assuming the carriage isn't one of those with square wheels.  We invariably cheat with the scale distances in modelling, and no reason why we can't do that in the vertical direction too.  In fact I rather think many model gradients are steeper than the Lickey.  Did they do that to the end, or was it served by auto trains?

 

Didn't know about Maiden Newton & Yelverton - it's good to know it wasn't just the impecunious GNoSR.

Edited by Michael Hodgson
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14 hours ago, Michael Hodgson said:

Only place I have heard of that definitely did it officially was Banff.

Gravity shunting was also practised at Eyemouth (ex-NBR) though not in NBR days. It seems that there wasn't sufficient space for tender locos to run round — after the Grouping the previously used tank locos from the NBR Berwick shed were replaced by ex-NER tender locos from Tweedmouth shed, and there wasn't sufficient space to run round — so the loop points were removed and gravity shunting instituted — which lasted until closure in 1962.

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14 hours ago, RailWest said:

>>>The symbols at the beginning of the Pryer books don't show the symbol for a hand point.....

 

Well, it certainly does in Volume 3 :-)

 

image.png.4432fc4e0519fad59cba36d883e47ed4.png

 

No symbols at all in my copy of Volume 4 and different symbols from those you have shown are used in Volume 5 onwards (when there is a symbols page - some of my volumes don't have one so maybe things changed with different editions?)

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On 13/04/2021 at 21:50, James Parker said:

I am struggling to interpret just one element of the signal box diagram produced by the signalling record society for Helston (GWR).  The diagram is here https://www.s-r-s.org.uk/html/gwf/S1195.htm (I wont copy it in case of breach of copyright).

The turnout which connects the engine loop and the siding (on the left hand side of the diagram) doesn't show a  'normal' position, isn't labelled 'sprung' and doesn't have a corresponding lever in the box.  I cant find any evidence in photos of a ground frame nor any reference to one.  So the question is, how was this turnout (and shunting operations in general) worked, particularly in the 1956 layout.  Its clear how you get (or rather a train gets) to the engine loop but not how the train gets to the siding, goods shed and places beyond.  Do I have to infer a ground frame or is there some mechanism, depicted by the symbol which appears on this diagram only for one turnout, which indicates some other means of operation?

'Signal Box Diagrams of the Great Western and Southern Railways (Pryor) has exactly the same symbology but equally no explanation.  Doubtless this is therefore obvious to those with a good knowledge of prototype working practice, but sadly not to me.

In reality on my (very, very slowly emerging) model, the turnout does of course have a point servo, so I can do what I want, but I'm keen to understand how the prototype would have been worked.

Are you still working on Helston? I am revisiting it as I head into retirment having first started many years ago. have you seen the "Cartoon of Helston" layout on RMweb?

regards

Andy

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I too am slowly at work on my own version of Helston. I am trying to establish what the signal frame would have looked like in 1930. I will be using the DCC Concepts levers and want to position and colour them as per the original frame if possible. Is there a document that sets out GWR practice for the colours of levers? Is there an early signal plan?

thanks

Andy

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Until it was replaced in 1958 the frame was a GWR Double-Twist pattern with levers at 5.1/2" centres.

Lever colours would have been simple: red for all signals (the distant was fixed), black for points and blue for the FPLs.

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52 minutes ago, Andy Keane said:

I too am slowly at work on my own version of Helston. I am trying to establish what the signal frame would have looked like in 1930. I will be using the DCC Concepts levers and want to position and colour them as per the original frame if possible. Is there a document that sets out GWR practice for the colours of levers? Is there an early signal plan?

thanks

Andy

See the thread above.  Whilst not applicable to a place like Helston, I believe practice in GWR days included additional colour conventions for signal levers to distinguish signals applicable to goods/slow/relief lines.

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