Provision of Arm and Lamp Repeaters on the S&DJR

[RailWest]

[Cross-posting from the S&DJR forum.]

 

I am researching the extent to which the S&DJR provided Arm and/or Lamp Repeaters in their signal-boxes (and some GFs.)

 

This is not an easy subject to examine, as most of the detail comes from information listed on signal-box diagrams, a practice which does not seem to have become common until about the 1930s. Even in the 1950s some diagrams had no such detail at all, but its absence can not be taken as a definite indication that no such repeaters were provided - it may be just that the original diagram negative was never updated.

 

My general impression is that initially the provision of Arm Repeaters was limited to Distant signals (not surprising perhaps, given their remote locations) and even then not all of those. Arm repeaters for Stop signals did exist in later years at some locations, possibly because of signals being moved further out; there were also a few provided on signals which IMHO should not have needed them, so maybe it had become the practice in BR days to provide them as a matter of course when making alterations?

 

Lamp Repeaters appear to have been very scarce - initially I found only six! Even Distant signals did not appear to have them as a rule, which I find strange - after all, if a train is approaching at night and the lamp is out and the driver has lost his bearings, then he's going to get a shock when the first he sees is the red light from a Home signal, so that extent I would have considered Lamp repeaters perhaps to have been even more important than Arm repeaters for Distant signals.

 

Although quite a few photos do exist of S&DJR signal-box interiors which show some repeaters, it is not always easy to determine their function and to which signal(s) they apply. Often the photos show only part of the instrument shelf anyway, so the record is incomplete.

 

Any thoughts and/or S&DJR-specific information would be appreciated - thanks!

[Michael Hodgson]

What you really want is not the box diagram - it's the wiring diagrams for the box - but those are almost invariably long gone.

 

Signalman were supposed to check that the signal had responded to the lever when pulled  and when restored, so you could hardly do that if you can't see it.  The rule of thumb is that semaphore repeaters would generally be provided if you couldn't see the signal from the box, although in cases where boxes were close together an adjacent signalman might be able to see and would be required to inform his colleague of signals that were misbehaving.   If you could see it, the repeater was unnecessary, although it might be felt justified in an area prone to fog and in later years they became more common anyway. 

 

You can't rely on diagrams even today to tell you whether a signal is repeated; if there is a repeater it's in the box somewhere, almost always on the block shelf adjacent to the relevant lever, so it's really a detail don't need the diagram to tell you.

 

What is more commonly shown on diagrams is "HNC" (Home Normal Control) which  prevents you from accepting a train from the box in rear unless the arm and lever are proved normal - implying that there is a detector on the arm, or similar safety controls which were gradually implemented on the more important routes, and I would assume the S&D would fall into this category.

 

An arm repeater works by means of a mechanical linkage at the top of the signal post, working an electrical contact.  Every repeater needed its own line wire from the signal back to the box, so you might be able to deduce from photos either of signals or even of the telegraph poles, though you'd be lucky to find enough good photos of those.  If the linkage was present, it's reasonable to deduce there was a repeater in the box.  If the telegraph poles are still in situ (or at the bottom of the embankment) it is possible to do a bit of archeologogy by counting the insulators or the cross arms and see whether there is one fewer once you get past the site of the signal (I have actually seen that deduction made on a closed line!).  Repeaters usually read "On/Wrong/Off" and gave a positive indication of the aspect shown; one polarity for on, the opposite for off, arm in mid-position or battery failure = open circuit and causes the needle to hang in the "Wrong" mid-position indication.  Wrong might indicate a need to adjust the tension on a signal wire.

 

A lamp repeater on some lines was provided to tell you when a lamp had gone out.  It worked by means of a simple pyrometer - a bi-metallic strip in the lamp casing which completed/broke a circuit depending on heat from the lamp.  However this didn't necessarily mean an indicator for every signal - sometimes a whole set of lamps would be connected in series and indicate on a single repeater.  If a lamp was unlit it would ring an audible alarm.  A switch would be provided to silence the alarm, and sombody would have to trudge out and relight it, at which point the alarm would sound again, so the switch would be put back.  It didn't matter that you didn't know which one had failed - that was obvious to the bloke in the dark with a box of matches! 

 

Some signals were provided with a more sophisticated indicator with 5 positions.  It combined arm and lamp indications, but only used a single line wire to the box, by inserting a resistance so the indicator needle didn't deflect fully.

 

 

[RailWest]

11 hours ago, Michael Hodgson said:

 

 

 

>>> What you really want is not the box diagram - it's the wiring diagrams for the box - but those are almost invariably long gone.

 

Sadly, you are right - almost none are known to exist, and those that do are merely for parts of the installation :-(

 

>>> You can't rely on diagrams even today to tell you whether a signal is repeated....

 

I think that depends upon age and BR Region. Certainly IMHO it seems to have been standard BR(S) practice to include such detail on box diagrams, whereas BR(WR) never did (which is not helpful when they replaced some of the S&DJR diagrams).

 

>>> What is more commonly shown on diagrams is "HNC" (Home Normal Control)....

 

Not something that I have ever seen on SR/GWR diagrams, though I know that it was done elsewhere.

To be honest, apart from 'upgrades' done in the Templecombe Jcn area, most S&DJR double-line boxes did not even have 'Line Clear' releases and even 'Tablet Out' releases were not universal on the single-line sections until quite late, so I doubt that they had much by way of 'sophistication' in their controls.

 

>>>..sometimes a whole set of lamps would be connected in series and indicate on a single repeater......

 

There were 3 instances of that practice that I have found so far on the S&DJR.

 

 

 

 

[Michael Hodgson]

1 hour ago, RailWest said:

I think that depends upon age and BR Region. Certainly IMHO it seems to have been standard BR(S) practice to include such detail on box diagrams, whereas BR(WR) never did (which is not helpful when they replaced some of the S&DJR diagrams).

 

Yes, it does seem to have been very much a Southern idea, and whilst helpful for your historical purpose, remember that box diagrams were intended for the signalman rather than the historian!  There have been a lot of different styles of drawing and practice as to their content between the various companies and over time.  For example some SR diagrams have the locking chart on them; that's another useful feature you don't see much elsewhere, though to my mind these diagrams are not as pretty as those without this info.  In short, I think you're lucky to have what you can still find.

 

It's rather like box instructions, most of those have not survived, so we don't know what deviations there were from the standard regulations in a lot of places.  The reason we still have diagrams of many but by no means all boxes is partly down to their being kept as souvenirs because they could be quite artistic, and partly down to box visitors (typically members of the SRS) who decided to copy them down or take photos.  Unfortunately for the modeller people these people omitted to copy box instructions or photograph block shelves; what existed in the way of cooking facilities etc also tends not be known as interior photos were generally of the lever frame or of unusual instruments, and what like the back wall looked like didn't really get any attention at the time. partly perhaps because of the practical difficulties of indoor photography. 

 

Documentation of the circuitry and interlocking was far too voluminous to keep, so it was perfectly logical that it just got chucked when a box or complete route ceased to exist.

[5BarVT]

2 hours ago, RailWest said:

>>> What is more commonly shown on diagrams is "HNC" (Home Normal Control)....

 

Not something that I have ever seen on SR/GWR diagrams, though I know that it was done elsewhere.

HNC I regard as LMR terminology (as that’s where I first came across it).  May be more widespread, but certainly not (G)WR where it was known as Interlinking when applied separately and just incorporated in One Acceptance Block (also known as Welwyn Block elsewhere).

Paul.

[The Stationmaster]

4 hours ago, 5BarVT said:

HNC I regard as LMR terminology (as that’s where I first came across it).  May be more widespread, but certainly not (G)WR where it was known as Interlinking when applied separately and just incorporated in One Acceptance Block (also known as Welwyn Block elsewhere).

Paul.

Agreed.  In fact it seems from Minute Books that first interlinking move in respect of acceptance on the GWR was to prove the Distant Signal arm not the Home Signal arm, the latter came later.  

 

Going back to the original question I would think one problem on the S%D Jt was lack pf power supplies particularly at the more remote locations.

Even at the end, according to those of my Signlmen who had come over from 'the Dorset' on redundancy when it had closed, there were examples of Section Signals with no block etc control so HNC style  interlinking would have been even less likely;  so nothing to drive a repeater.  Obviousy batteries would have been used and their presence, if it can be found from photos and other information might help? 

[5BarVT]

Boxes I worked on in the DO in 1980/81 still used dry cells for arm and lamp repeaters, so the lack of power wouldn’t affect the ability to repeat.  However, those boxes all has supplies back at the box to charge the box batteries.

If the box was in the middle of nowhere still using dry cells for block batteries, then the ability to do anything as controls (rather than indications for the signalman) would be limited.

Paul.

[Michael Hodgson]

Batteries for arm/lamp repeaters were often in the locs, and you might find a heap of discarded batteries buried in the long grass at the bottom of the embankment.

[5BarVT]

14 hours ago, Michael Hodgson said:

Batteries for arm/lamp repeaters were often in the locs, and you might find a heap of discarded batteries buried in the long grass at the bottom of the embankment.

Shhh . . .!

[RailWest]

I've broadened my research now to include the S&DJR's use of Electric Repeaters in general (not just Arm and Lamp) and an initial write-up can be found here for those who are interested:-

 

www.trainweb.org/railwest/railco/sdjr/sigmisc.html#repeaters

 

Comments, corrections and extra information always welcome !

 

Admittedly there is a lot more to this subject, especially with the early years, but I don't really have the time at the moment to delve into all the ramifications in details. Primarily I just want to write-up a 'general overview' for those who may want a simple explanation of the basics.

Edited November 4, 2023 by RailWest

[Robert Shrives]

On 30/10/2023 at 12:31, 5BarVT said:

Shhh . . .!

Pop to  Jewellery Quarter and end of down platform is a big pile of discarded cells... so it goes on today!