Point rodding and signal wires

[TrevorP1]

Much interesting information on here. All good for when I take the plunge with mine. Thank you to all contributors. Perhaps I could ask a couple of prototype based questions which might be of help to transfer to a model.

 

Yesterday I spent an interesting hour or two in Exeter West Box at Crewe Heritage Centre. It was being enthusiastically and knowledgeably operated by three young men, at least two of whom were young enough to be my grandsons. (Ouch!) When they realised I - kind of! - knew what I was talking about and familiar with the area they completely opened up and the conversation danced back and forth on many topics. One of the things mentioned very briefly was the electric operation of points and signals in a traditional, ie semaphore era, environment.

 

As I drove home I thought:

• What were the criteria for the installion of this kind of equipment? Distance yes II guess) but how far for the box?
• What did it look like? I have a couple of DCC concepts dummy electric point machines - would they be correct for the steam era?
• What did the cabling look like and how was it taken to the pointwork or signal?

I'm thinking of BR western region here but any information would be interesting. Questions, questions. As usual, the more you learn the more you realise you don't know! 

 

 

 

 

[The Stationmaster]

How far back do you want to go and which Railway Compny or BR region have you in mind apart from the date?

 

If you are specifically concerned with the power operation of [points using an electric motor or electromagnets the first installation of the LNWR's 'Crewe System' was brought into use in December 1898 at Gresty Lane, Crewe.  The GW was using power lever frames with electrically operated points at number of locations in the first decade of the 20th century.  Various other railways other Railways also used power point operation although they used electro-pneumatic point operation - widespread on the LSWR for example and the first installation had been at Granary Jcn on the GER in January 1899, the L&YR also used electro-pneumatic point operation.

 

The Great War definitely delayed the spread of power signalling - including one signalbox power 'lever frame' intended for installation at Victoria SE&CR going to the bottom of the Atlantic after the ship carrying from the USA was sunk by a U-Boat..  Power operation - usually, but not always associated with the introduction of colour light signalling, got underway in a bigger sense in the late 1920s continuing on through to the outbreak of WWII with all four of the Grouped Railways introducing various schemes although generally these were restricted in the size of the area controlled by a single signalbox.

 

Work resumed in the late 1940s and by the late 1950s power boxes were able to control geographically larger areas because of teh development of electronic '2-wire' systems to operate am nd monitor remotely sited interlockings.  This by the early- mid 1960s power signal boxes - all using control panels by then so called 'panel boxes' by some railwaymen - could control tens of route miles of railway  from a single location. 

 

So in some places power and electrically worked points, using varioy us different designs of point machine go back a very long way.  The widely used Westinghouse M3 point machine first appeared in 1823 and was used by all the Companies and later BR Regions in some way or another.  Still very common into the 1980s II doubt if there are still any left in mainline use but you never know.  The M3A was superseded by the Westinghouse M63 in 1967/68 and some of these are probably still around

 

An important development in the late 1920s/early '30s was the hand generator which allowed a Signalman to generate sufficient current to operate a point machine by turning a handle on the side of the machine.  This meant that power points could then be installed in older signal boxes which had no electricity supply in order to operate points which could be much further from the 'box than the maximum permitted distance worked by mechanical rodding.  This development was such that during WWII it v became relatively simple to convert refuge sidings into loops as there was no need to pay on a power supply for the addditional point(s) which were more than liklely to eb more than 350 yds from the box. There were often used - certainly on the WR, -with what I have heard referred to as a  Style C point machine but I can't find any details of these on the 'net and I took no photos of them.  Other manufacturers have also supplied electric point machines over the years so appearances have varied but take care with the DCC Concepts Westinghouse machine in 4mm scale because it is a model of an electro-pneumatic machine  - not an electric one.

 

The big advantage of power operation of points is that they can be a greater distance from the signal box which works them.  Thus as things stood in the 1890s/early 20th century facing points had to be no more than 180 yds from the box which worked them while trailiming points had to be no more than 300 yds from the 'box.  In the 1920s the permitted distance for both trailing and facing points worked by rodding was increased to a maximum of 350 yds from the signal box which worked those points.

 

Hope this helpsa bit.

[TrevorP1]

46 minutes ago, The Stationmaster said:

How far back do you want to go and which Railway Compny or BR region have you in mind apart from the date?

 

If you are specifically concerned with the power operation of [points using an electric motor or electromagnets the first installation of the LNWR's 'Crewe System' was brought into use in December 1898 at Gresty Lane, Crewe.  The GW was using power lever frames with electrically operated points at number of locations in the first decade of the 20th century.  Various other railways other Railways also used power point operation although they used electro-pneumatic point operation - widespread on the LSWR for example and the first installation had been at Granary Jcn on the GER in January 1899, the L&YR also used electro-pneumatic point operation.

 

The Great War definitely delayed the spread of power signalling - including one signalbox power 'lever frame' intended for installation at Victoria SE&CR going to the bottom of the Atlantic after the ship carrying from the USA was sunk by a U-Boat..  Power operation - usually, but not always associated with the introduction of colour light signalling, got underway in a bigger sense in the late 1920s continuing on through to the outbreak of WWII with all four of the Grouped Railways introducing various schemes although generally these were restricted in the size of the area controlled by a single signalbox.

 

Work resumed in the late 1940s and by the late 1950s power boxes were able to control geographically larger areas because of teh development of electronic '2-wire' systems to operate am nd monitor remotely sited interlockings.  This by the early- mid 1960s power signal boxes - all using control panels by then so called 'panel boxes' by some railwaymen - could control tens of route miles of railway  from a single location. 

 

So in some places power and electrically worked points, using varioy us different designs of point machine go back a very long way.  The widely used Westinghouse M3 point machine first appeared in 1823 and was used by all the Companies and later BR Regions in some way or another.  Still very common into the 1980s II doubt if there are still any left in mainline use but you never know.  The M3A was superseded by the Westinghouse M63 in 1967/68 and some of these are probably still around

 

An important development in the late 1920s/early '30s was the hand generator which allowed a Signalman to generate sufficient current to operate a point machine by turning a handle on the side of the machine.  This meant that power points could then be installed in older signal boxes which had no electricity supply in order to operate points which could be much further from the 'box than the maximum permitted distance worked by mechanical rodding.  This development was such that during WWII it v became relatively simple to convert refuge sidings into loops as there was no need to pay on a power supply for the addditional point(s) which were more than liklely to eb more than 350 yds from the box. There were often used - certainly on the WR, -with what I have heard referred to as a  Style C point machine but I can't find any details of these on the 'net and I took no photos of them.  Other manufacturers have also supplied electric point machines over the years so appearances have varied but take care with the DCC Concepts Westinghouse machine in 4mm scale because it is a model of an electro-pneumatic machine  - not an electric one.

 

The big advantage of power operation of points is that they can be a greater distance from the signal box which works them.  Thus as things stood in the 1890s/early 20th century facing points had to be no more than 180 yds from the box which worked them while trailiming points had to be no more than 300 yds from the 'box.  In the 1920s the permitted distance for both trailing and facing points worked by rodding was increased to a maximum of 350 yds from the signal box which worked those points.

 

Hope this helpsa bit.

 

Thank you Mike. I certainly hadn't realised that power operation went back that far, having said that I'm not surprised in a way.

 

To be more specific - and I guess selfish in a way - I was thinking of things that might have been seen on the Western Region by and during  the 1950s, more as an addition to a mechanical box. As a for instance, the sort of case you mentioned where refuge sidings were converted into loops.

 

A bit of googling found this: Seimens Point Machine and Facing Point Switch Machine on the Warwickshire Railways web site. These are related to the expansion of Birmingham Snow Hill early in the twentieth century. 

[TrevorP1]

In doing a bit more web searching I found these on eBay  Pack of 5 3D resin printed OO gauge Westinghouse M3 style point motors .

[Michael Hodgson]

One of the things about mechanical working of points is that the limitation on distance from the box tended to mean that even wayside stations often needed at least two boxes, one at each end, and bigger places like Exeter obviously had a lot more.  Power working of the more distant points and signals meant that you could close the smaller boxes and that saved 4 wage packets (one for each of shift plus a relief to cover holdays etc).  So the capital investment was usually cost justifiable.

 

It also meant less mechanical stuff for S&T to have to maintain.  Of course when a remote point failed, it might still need to be moved, so there were arrangements for the point motors to be wound over manually, release of the handle needing to be kept secure for obvious reasons.

 

The early Snow Hill scheme was wasn't typical, as it had proved rather unsatisfactory and had to be re-done.

[The Stationmaster]

18 hours ago, TrevorP1 said:

 

Thank you Mike. I certainly hadn't realised that power operation went back that far, having said that I'm not surprised in a way.

 

To be more specific - and I guess selfish in a way - I was thinking of things that might have been seen on the Western Region by and during  the 1950s, more as an addition to a mechanical box. As a for instance, the sort of case you mentioned where refuge sidings were converted into loops.

 

A bit of googling found this: Seimens Point Machine and Facing Point Switch Machine on the Warwickshire Railways web site. These are related to the expansion of Birmingham Snow Hill early in the twentieth century. 

Those Siemens machines were installed before the Great war when two power  'boxes were provided at Snow Hill.  I know they (some or all?) were replaced at some time by GRS 5A machines - which the GWR used in various places in its 1930s resignalling schemes.

 

18 hours ago, TrevorP1 said:

In doing a bit more web searching I found these on eBay  Pack of 5 3D resin printed OO gauge Westinghouse M3 style point motors .

Every time I look at the prototype photo in that  I wonder if someone has pinched one of my photos as i have one of that point taken from exactly that angle and in that condition prior to it being relaid!    That machine lasted into this century in everyday use.

 

Coming back to the OP I have hada look on the'net for suitable photos as I'm fairly sure that I haven't got any of the type of machine you're after (i will check my photos but I doubt any chance of success).  You could, I think due to teh lack of anything else, maybe use an M3 as they first appeared in GWR in the 1930s and were still being installed up until the appearance of the M63.  The one in the photo mentioned above was still in use in 2009 and I'm checking my photos to try to pin down the year in which it actually went,

Edited May 10, 2022 by The Stationmaster
correct typos

[Harlequin]

Hi Mike @The Stationmaster,

On page 173 of GWR Signalling Practice (Smith) there is a photo of an electric point motor at Highclere. It's a low-voltage Westinghouse operated from the "Hurdy-gurdy" in the 'box but the caption doesn't say what type it is.

Do you happen to know? Is it an M3 as discussed above?

 

[TrevorP1]

7 hours ago, The Stationmaster said:

Coming back to the OP I have hada look on the'net for suitable photos as I'm fairly sure that I haven't got any of the type of machine you're after (i will check my photos but I doubt any chance of success).  You could, I think due to teh lack of anything else, maybe use an M3 as they first appeared in GWR in the 1930s and were still being installed up until the appearance of the M63.  The one in the photo mentioned above was still in use in 2009 and I'm checking my photos to try to pin down the year in which it actually went,

 

Thanks once again Mike. I have a set of points - sorry, switches and crossings! - that are at least ¼ mile from the nearest possible position of my, as yet unbuilt, signal box. So for the sake of a fiver I'm inclined to buy a pack of the M3 machines for the 'stash'.

 

1 hour ago, Harlequin said:

Hi Mike @The Stationmaster,

On page 173 of GWR Signalling Practice (Smith) there is a photo of an electric point motor at Highclere. It's a low-voltage Westinghouse operated from the "Hurdy-gurdy" in the 'box but the caption doesn't say what type it is.

Do you happen to know? Is it an M3 as discussed above?

 

 

Phil, I don't have that book but I do have Burghclere Signalman. There is a photo of the hurdy gurdy on page 7, credited to Westinghouse Brake and Signal Co. The caption mentions that  this was installed in 1942 and that all the boxes from Highclere southwards were fitted with these at around this time. Presumably this was in connection with the wartime upgrades and preparation for D-Day. Later today I'll scan through the text to see if there are any other mentions.

[micknich2003]

The earliest ref I have in my own line of research to an Hand Generator is at Kirkella Cutting H&B Section July 1926. I recall reading somewhere, they were in use in Ireland some years earlier.

[TheSignalEngineer]

On 09/05/2022 at 17:12, The Stationmaster said:

Still very common into the 1980s II doubt if there are still any left in mainline use but you never know.  The M3A was superseded by the Westinghouse M63 in 1967/68 and some of these are probably still around

The M3A was the version of the M3 developed for use on AC electrified lines IIRC.

 

12 hours ago, The Stationmaster said:

Those Siemens machines were installed before the Great war when two power  'boxes were provided at Snow Hill.  I know they (some or all?) were replaced at some time by GRS 5A machines - which the GWR used in various places in its 1930s resignalling schemes.

Early Siemens machine at Snow Hill North

https://www.warwickshirerailways.com/gwr/gwrbsh1672.htm

Later machine at Snow Hill South

https://www.warwickshirerailways.com/gwr/gwrbsh1740.htm

 

From dated photograph I suspect that these lasted until the late 1930s before being progressively replaced by GRS machines.

 

Circa 1968/9 I was tasked with doing a review of the S&T stores stock levels at Birmingham compared to annual usage. Whilst going through the stock bins I found a large quantity of spare parts for original Siemens point and signal machines as installed at Snow Hill North, Snow Hill South and Hockley North. When the last of these boxes, Hockley North, was taken out of use c1967 there was a lot of equipment made by Krupps before WW1 still in use there.

 

 

 

5 hours ago, Harlequin said:

On page 173 of GWR Signalling Practice (Smith) there is a photo of an electric point motor at Highclere. It's a low-voltage Westinghouse operated from the "Hurdy-gurdy" in the 'box but the caption doesn't say what type it is.

I don't have the book but I expect it would have been a Westinghouse Style C machine. We still had one at the exit to the Up Loop on the Oxford line at Aynho Junction at least into the 1980s. Not a very good picture as it is a low res scan of a shot taken with a miniature pocket camera, but this was a Style C machine with the cover off showing rodding for operation of the combined FPL and detector box in the four-foot.

 

(if anyone wants a high res scan of the print I can PM one, but it may be a bit big to post in the topic.)

[PjKing1]

I hope this is the right place to ask

this but how common was it to have point rodding and colour light signals?  I’m guessing it happened going by this photo (not mine)

Edited May 10, 2022 by PjKing1

[bécasse]

Quite a common arrangement for installations up until about the mid-1960s, it obviously required a locally sited signal box unless only very simple pointwork (eg a single siding or crossover) was involved when a (remotely released) local ground frame might be all that was needed to work the points.

[PjKing1]

5 minutes ago, bécasse said:

Quite a common arrangement for installations up until about the mid-1960s, it obviously required a locally sited signal box unless only very simple pointwork (eg a single siding or crossover) was involved when a (remotely released) local ground frame might be all that was needed to work the points.

Cheers buddy 

[TrevorP1]

20 hours ago, TrevorP1 said:

 

Phil, I don't have that book but I do have Burghclere Signalman. There is a photo of the hurdy gurdy on page 7, credited to Westinghouse Brake and Signal Co. The caption mentions that  this was installed in 1942 and that all the boxes from Highclere southwards were fitted with these at around this time. Presumably this was in connection with the wartime upgrades and preparation for D-Day. Later today I'll scan through the text to see if there are any other mentions.

 

A look through Burghclere Signalman didn't reveal a mention of the actual type of machine. There is a photo of the installation but it's only a general shot. Here is a crop of the motor for those with better eyes/knowledge than me!

 

 

 

15 hours ago, TheSignalEngineer said:

 

I don't have the book but I expect it would have been a Westinghouse Style C machine. We still had one at the exit to the Up Loop on the Oxford line at Aynho Junction at least into the 1980s. Not a very good picture as it is a low res scan of a shot taken with a miniature pocket camera, but this was a Style C machine with the cover off showing rodding for operation of the combined FPL and detector box in the four-foot.

 

 

(if anyone wants a high res scan of the print I can PM one, but it may be a bit big to post in the topic.)

 

That's interesting. I'd like a larger copy please if possible, I'll pm you.

 

Some more web searching revealed a similar conversation on the Scalefour Forum which led me to Style M Point Machine Manual. on the Victorian Railways website. Victorian as in Australia but the equipment looks the same.

 

As ever this leads to more questions...

• In situations were there was more than one pair of points, would that require another hand generator or could that be switched?
• Also, how did the cable reach the pointwork, ie in trunking as per modern practice or on poles? I've read somewhere that about 30volts was used so presumably there was quite a high current and heavy cabling was needed.

Edited May 11, 2022 by TrevorP1
To include better photo crop. Will delete if copyright problems.

[RailWest]

>>>>...in situations were there was more than one pair of points, would that require another hand generator or could that be switched...

 

By coincidence, I've been looking at photos of a 1930s installation which probably had Westinghouse 'Style C' machines. There is one example of a point leading into a goods line, with an associated trailing trap-point; there was just a single motor attached to the former with normal mechanical rodding from it to work the latter.

[brainh]

On the subject of point rodding & colour lights.  It was common around Crewe. I started on the S&T from school in July 1969 and one of the 1st jobs I was on was to renew all the point rodding controlled by Crewe Coalyard Signal Box.  This included all the signal wires as these were still all ground discs at the time.  At that time Sorting Sidings South, Basford Hall Junction, North Stafford Sidings & Salop Goods Junction all had this combination. From memory I'm pretty certain that Crewe Steelworks & Gresty Lane No2 Boxes were also the same   

[The Stationmaster]

20 hours ago, Harlequin said:

Hi Mike @The Stationmaster,

On page 173 of GWR Signalling Practice (Smith) there is a photo of an electric point motor at Highclere. It's a low-voltage Westinghouse operated from the "Hurdy-gurdy" in the 'box but the caption doesn't say what type it is.

Do you happen to know? Is it an M3 as discussed above?

 

Phil,

 Very helpful link thanks as that is what I was always told is a Style C machine.  And yes, that type was normally the one used with a hurdy gurdy.  That got me looking through Kevin Robertson's 2nd book about the DN&S ('A New History') and there's an excellent ' looking down on your layout' eye view of one on page 193 in that book plus a couple of not so good views on pages 108 and 109.

 

The Style C - as I will continue to call them until I know different - is  a very different beast from the M3, in several respects.  First, and most important it drives the FPL via a separate rod which comes out of the end of the machine and drives the FPL in exactly the same way as one is driven on a mechanically worked point although without a lock(ing) bar as these machines were usually accompanied by a track circuit.  The stretcher bar is driven in the usual way and the machines did not - AFAIK - include detection (which an M3 does) so could be readily used with mechanical detection (sas in that photo on page 173) or, no doubt, a  separate electric detector if that was needed (the GWR used at leats two different designs of electric detector).

 

The big visual difference - apart from the FPL arrangement - is that the drive end of the machine is covered by a plain rectangular sheet metal cover unlike the cast lids etc used on an M3.  This is an M3 at Twyford and still in use when i took this photo in 2009.  As you can see it has built-in detection (the three rods at the left hand end.  This version has a tubular item on that same end of the machine which is a cover for an early capability in the design to separately operate an FPL in the same way as the StyleC or indeed the early Siemens installation at Birmingham Snow Hill.

 

 

[The Stationmaster]

15 hours ago, PjKing1 said:

I hope this is the right place to ask

this but how common was it to have point rodding and colour light signals?  I’m guessing it happened going by this photo (not mine)

A lot of it occurred when a major installations of colour light signalling took place as part of various schemes in the 1960s.  It happened on the WCML when the original resignalling budget for electrification was cut and mechanical boxes were retained between Crewe and the areas controlled by Nuneaton and Rugby psbs which saw a reversion o to the original policy of new power boxes.  It happened on the WR at various locations under the Reading - Hayes MAS scheme in the first half of the 1960s, it happened in Scotland under some of the Clydeside electreification schmem, plus on parts of the Tilbury Line and of course had been there in some places for the original Southend electrification extension.  and lots of it remained for several decades  in various places.  So overall - 'quite common'

[The Stationmaster]

4 hours ago, RailWest said:

>>>>...in situations were there was more than one pair of points, would that require another hand generator or could that be switched...

 

By coincidence, I've been looking at photos of a 1930s installation which probably had Westinghouse 'Style C' machines. There is one example of a point leading into a goods line, with an associated trailing trap-point; there was just a single motor attached to the former with normal mechanical rodding from it to work the latter.

The Western did that in a number of places with the trap (but only a trailing trap as far as I'm aware) driven off the point machine at the facing end.  Quite why they bothered when a spring worked trap would have been justr as good I don't know but maybe the spring points weren't consider sufficiently reliable?   The reason I say that is every such arrangement I have seen a photo of looked in poor adjustment and I expect teh wheels did as much to securely close the trap as the ridding from the point machine.  I doubt they would have been reliable for a facing move should one ever be necessary.

[5BarVT]

6 hours ago, TrevorP1 said:

As ever this leads to more questions...

• In situations were there was more than one pair of points, would that require another hand generator or could that be switched?

This is how I think it would have been done, not how I know it was done.

As far as I know, the method of operation was to pull the lever as normal then go to the hurdy  gurdy and wind away until the point had moved fully across.  So if there were more than one set, I imagine the procedure would be pull one lever, wind away ‘til done, pull second lever, wind away again.  I believe it took quite a long time to get the points across so I wouldn’t want to have to do too many ends in succession.

Paul.

[5BarVT]

1 hour ago, The Stationmaster said:

The Western did that in a number of places with the trap (but only a trailing trap as far as I'm aware) driven off the point machine at the facing end.  Quite why they bothered when a spring worked trap would have been justr as good I don't know but maybe the spring points weren't consider sufficiently reliable?

Hi Mike,

60s schemes (Alstone Up Loop for one) did something similar.  The trap was a spring and the rod from the facing end was to force it over if the spring failed.  (Or possibly to fail the facing end if the machine couldn’t manage the load.)

Could that have been the arrangement with the Style C too?

Paul.

[Harlequin]

22 minutes ago, 5BarVT said:

This is how I think it would have been done, not how I know it was done.

As far as I know, the method of operation was to pull the lever as normal then go to the hurdy  gurdy and wind away until the point had moved fully across.  So if there were more than one set, I imagine the procedure would be pull one lever, wind away ‘til done, pull second lever, wind away again.  I believe it took quite a long time to get the points across so I wouldn’t want to have to do too many ends in succession.

Paul.

 

According to "GWR Signalling Practice" (my summary):

The relevant levers had extra slots at the 1/4 and 3/4 positions of the lever guides. You pull the lever to the 3/4 slot position and interlocking prevents it going any further. You then wind the hurdy-gurdy until the indicator shows the points have moved the full distance (not sure what indicator). Then the lever is released by the interlocking and it can be moved to the normal position. Same in reverse using the other slot.

 

I guess that the slots connect the generator to the point motor electrically and maybe each slot reverses the polarity of the other?

 

I think Kevin Robertson describes exactly this procedure in one of his books - possibly Burghclere Signalman or the Sutton Scotney book. I got the impression that these electric point motors were not 100% reliable, with signalmen worrying about setting routes that required using them and so getting it done as early as possible in case there was a problem. I think sometimes they had to go through the process a few times before the points were provably set correctly.

 

[RailWest]

Yes, the 'B' and 'D' positions of the lever. 

 

The idea is that, by moving the lever from N to D, but NOT all the way to R, you move the locking sufficient to prevent conflicting moves, but not enough to release other moves until it has been proven that the point has moved fully over to the reverse position. Once that has been detected at the point, then the electric lock on the lever is freed to enable you to move the lever from D to R, at which stage the locking for the signal(s) for the new route becomes free. Conversely, when putting back, you go from R to B, wait for the points to be motored back and proven normal, then you can move from B to N.

 

Indicator in the signal-box could be a typical circular one like an arm repeater or similar, but with three indications NORMAL /  -  / REVERSE for the point position.

 

If you look at the picture here (Williton on the WSR) levers 12 and 16 are for motor points. The round white-faced point indicators are above them on the front of the shelf. Look closely at the lever quadrants and you will see the B and D position notches close to each other near the mid-stroke.

 

Edited May 11, 2022 by RailWest

[TrevorP1]

21 minutes ago, Harlequin said:

 

According to "GWR Signalling Practice" (my summary):

The relevant levers had extra slots at the 1/4 and 3/4 positions of the lever guides. You pull the lever to the 3/4 slot position and interlocking prevents it going any further. You then wind the hurdy-gurdy until the indicator shows the points have moved the full distance (not sure what indicator). Then the lever is released by the interlocking and it can be moved to the normal position. Same in reverse using the other slot.

 

I guess that the slots connect the generator to the point motor electrically and maybe each slot reverses the polarity of the other?

 

I think Kevin Robertson describes exactly this procedure in one of his books - possibly Burghclere Signalman or the Sutton Scotney book. I got the impression that these electric point motors were not 100% reliable, with signalmen worrying about setting routes that required using them and so getting it done as early as possible in case there was a problem. I think sometimes they had to go through the process a few times before the points were provably set correctly.

 

 

Yes, I've read that somewhere and it may well have been in Burghclere Signalman. I find that I read and enjoy these accounts but when you come to consider things for a model there are dozens of questions that crop up. 🙂 

[5BarVT]

1 hour ago, RailWest said:

Yes, the 'B' and 'D' positions of the lever. 

For those that don’t follow signalling terminology in as much detail as some of us . . .

Between N and R are 5 other positions A to E.  C is the easy one it’s right in the middle and is very rarely (if ever) used.  A is very close to N and E is very close to R.  Usually (on G(WR) at least) as lever band contacts that are not pure N or R (thus NA or RE).  That leaves B and D which are usually a lock position before the lever gets to the final N or R position about 1/4 and 3/4 through the quadrant.  (As described by RailWest and Harlequin above.)

Paul.