Yellow drop flap signals

Any aspect related to the structures and equipment on the Caledonian Railway Company.
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John Lindsay
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Yellow drop flap signals

Post by John Lindsay »

I have just read that the painting of ground signals yellow to indicate that they can be passed when in the on position if the movement does not take the train onto the running line is a fairly recent thing. I have checked Jim Summers' book, and he makes no mention of the flaps being coloured anything other than red, which seems to back up the first statement.
My questions are,
1. can anyone confirm when yellow was introduced on (ex) Caley lines and
2. before the introduction of yellow, did the signal have to be cleared before a train passed it even if it was not moving on to the running line?

Many thanks

John
dunalastairv
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Re: Yellow drop flap signals

Post by dunalastairv »

I can offer some information on the first part of your question - the use of yellow is actually said to have started just before the Grouping, with the Barry Railway in South Wales, but in the main the conversion of distant signals began around 1924 to 1925, with much encouragement from the Railway Clearing House, on both ex-Caledonian and all other lines in Great Britain. Of course it was a very slow process and some distants on the Great Western for example, still hadn't been done by the time WWII began. The process was speeded up by the adoption of upper-quadrant signals, gradually installed on main lines in particular, but the fact is one or two distant signals in remote places were never actually converted to yellow at all.
Jim Summers
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Re: Yellow drop flap signals

Post by Jim Summers »

John,
Anent your question 1, I do not think the Caledonian used any yellow dropflaps.
Anent your question 2, I expect that two signals would be provided, one for shunting ahead and one for entry to the main line.

As a matter of interest (I hope) here is a model of a signal in Fife dealing with such a situation. In this case it was a large semaphore signal, rather than dropflaps, but you get the idea. The high arm is the one controlling exit to the main line, while the lower arms both come off together and allow shunting to and fro, but with no authority to enter the main line. They have to be reversed to permit the exit signal to come off.

JimS
Lammerlaws Yard signal  by Jim compressed.JPG
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John Lindsay
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Re: Yellow drop flap signals

Post by John Lindsay »

Many thanks Jim for the information; it ties up with the late introduction of the “yellow shunt signal”. However, I remain in a puzzle about how the system might work when only one signal is provided.

I've attached a small file showing the specific type of situation I am wondering about.

It’s actually from Tyndrum in Caley days, but it’s the same arrangement as at Biggar. The lower line is the single line going away into section to the right and into the station passing loop to the left; the upper is the exit from the goods yard and the headshunt.

The cross over points, facing point lock and drop-flap signal are all controlled by a two lever ground frame released by the section tablet.

There is a good photo of the ground frame in both your book on Caley signalling and in Peebles Railways. It shows two levers, one of which is painted in two colours. As the photo is black and white, I can’t tell what the lever colours are, but I had assumed one was for the combined points and fpl and the other was for the signal.

With a red painted drop-flap signal, there seems to be three possible ways of working:
1 With the signal lever in the normal position – the flap signal is off
o The signal would then be off for movements into the headshunt
o For operation of the ground frame, the signal would be put to “on” by operating the lever, the points reversed and locked with the other lever and then the signal lever placed back to normal, clearing the signal for movements out onto the running line

2 If the lever arrangement is actually one lever for the points and the other for both the fpl and the signal
o In this case, again, the signal is clear with the lever normal – the lever being reversed to put the signal to danger and unlock the points
o Once the points had been reversed, the lock and signal could be returned to normal for exit/entry to/from the yard.

3 The signal is cleared only for exit onto the running line and a local instructions allows movements to pass the signal at danger into the headshunt

Do we know which of the above applied or if there is another explanation?

Many thanks

John
Attachments
tyndrum.jpg
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Jim Summers
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Re: Yellow drop flap signals

Post by Jim Summers »

John,

My thoughts are that the dropflap controlled entrance from the yard to the single line.
What you are thinking is a headshunt is probably not, but is simply the trapping arrangement to protect anything escaping on to the single line inadvertently.

In my view, any shunting would be done by a train engine, leaving part of its train in the station, and it would use the set of points on the main line as part of the shunting movement, in other words as a headshunt, though fouling the single line (which is covered in regulations).
So the dropflap would remain dropped during shunting, the train would be assembled on the main line in the station, and get its authority to proceed on to the single line in the normal way.

I have not yet had a chance to check up any documentation yet, but my thoughts meantime might be of interest.

Jim
John Lindsay
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Re: Yellow drop flap signals

Post by John Lindsay »

Hi Jim

That makes a lot of sense. I did wonder why the dead ends were so short, but never considered that they might only be for runaway protection.

It does put a constraint on the shunting opportunities, but I don't suppose the yards concerned were ever that busy.

Many thanks

John
David Elvy
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Re: Yellow drop flap signals

Post by David Elvy »

I have been following this thread with interest, especially to see Jim S’s reply.

Regards headshunts, one station I did once look to model was Dalmally which did have a full headshunt which ran parallel to the main line but didn’t, as far as I’m aware, have a drop signal to enter the main line but did have one to go from the siding to the headshunt http://www.oban-line.info/da1/da1.html a different hand but still interesting in a similar vein.

David
John Lindsay
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Re: Yellow drop flap signals

Post by John Lindsay »

Yes, Dalmally makes an interesting comparison.

In the absence of a signal for exit onto the up loop, I guess the signalman would use his flags.

I wonder why the different approach was taken at Tyndrum, just up the line.

Cheers

John
Jim Summers
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Re: Yellow drop flap signals

Post by Jim Summers »

John,

Looking at Simon Lowe's splendid C&O website on the signalling ( http://www.oban-line.info/obs1/obs1.html ), you will find a summary of the Inspecting Officer's remarks when they shortened the passenger loop to get a bigger length on the goods end. He particularly mentions the run-off arrangements at each end (and was pleased to note they existed!), which rather bears out my point.

As to the reason for the ground frame, I haven't succeeded in getting an accurate measurement of the distances, but my guess is that the ground frame was needed at Tyndrum because the distance from the box exceeded the then maximum for point rodding.

JimS
John Lindsay
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Re: Yellow drop flap signals

Post by John Lindsay »

I have a follow up question!

The layout above shows Biggar station. The ground frame that controlled it is shown on page 146 of Jim Summers' book on Caledonian Railway Signalling. The lever on the operator's left is painted two colours and that on the right, one. It being black and white, I don't know what the colours are.

The three functions, I guess, are facing point lock, points and ground signal.

Does anyone know what the combination and sequence would have been?

Thanks

John
dunalastairv
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Re: Yellow drop flap signals

Post by dunalastairv »

A very good question and I'll let Jim S. confirm, but 'scratchings' on the two-lever frame we've acquired suggest blue/brown for the left lever and all-over black on the right, (which of course actually operated the points). I don't think the colour can be red on the left lever because that would imply that you could give a clear on the ground signal before the points were reversed.
John Lindsay
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Joined: Mon Aug 27, 2012 10:28 am

Re: Yellow drop flap signals

Post by John Lindsay »

After posting the question the other day, I did a little more digging into some other info I had.

I found the attached diagram on page 255 of Railway Signal Engineering (Mechanical), by Leonard Lewis 1912 (available as a Google download). It seems to be one possibility for the two lever frame. If it was like this, the two-lever frame you got may have one lever painter blue and red. I believe Mr Lewis worked for the Caledonian.

Another possibility might be a "economical point lock" which uses one lever to both withdraw the lock and change the points - but for a crossover where two points are operated, rather than just one, this seems a lot to ask of one movement.

Cheers

John
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ground frame small.jpg
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dunalastairv
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Re: Yellow drop flap signals

Post by dunalastairv »

Now that is a revelation and I think you must be right, There definitely was a ground signal at the location our frame came from. Thank you.
Jim Summers
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Re: Yellow drop flap signals

Post by Jim Summers »

John has beaten me to it.
Mr Lewis is indeed the authority, whom I was about to consult once again.
He did indeed work for the Caledonian, and I have always found it interesting that they seem to have condoned/encouraged his post as a lecturer at the college. His diagrams of layouts are fundamentally Caledonian, though not identified as such.

He is available on the web, but I am fortunate to have a hard copy of his second, revised edition - a real treasure.

JimS
dunalastairv
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Re: Yellow drop flap signals

Post by dunalastairv »

Message for John Lindsay on this subject: you are absolutely right about the operation and colours of a two-lever locking frame: page 64 of Northern Portion Appendix of the W.T.T., dated May 1915, ( the issue reproduced by the C.R.A.), contains this gem:-

"The Points Locking frames with two levers are worked as under:-
To unlock the points, No. 1 lever must be drawn to the notch half-way over the frame, when No. 2 lever, which works the points, can be worked as required.
When No. 2 lever is drawn over, and the points set for the sidings, No. 1 can be drawn completely over to clear the siding signal.
To put back the siding signal to danger, No 1 lever must first be put forward to the notch; No. 2 can then be worked to set the points for the main line, after which No.1 must be put completely forward to its normal position, to allow tablet working to proceed."
John Lindsay
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Re: Yellow drop flap signals

Post by John Lindsay »

Many thanks dunalastairV - it's good to have it confirmed from another source.
Bill_Gensheet
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Re: Yellow drop flap signals

Post by Bill_Gensheet »

Jim Summers wrote:John,

My thoughts are that the dropflap controlled entrance from the yard to the single line.
What you are thinking is a headshunt is probably not, but is simply the trapping arrangement to protect anything escaping on to the single line inadvertently.
I have also been looking at Tyndrum, and believe that there would be a useable headshunt. The 1953 diagram on http://www.oban-line.info/ty1/ty1.html shows the ground frame removed, so the only yard access would be in and out of the headshunt. I suspect this could have been left over 1873 main line.
Jim Summers wrote: As to the reason for the ground frame, I haven't succeeded in getting an accurate measurement of the distances, but my guess is that the ground frame was needed at Tyndrum because the distance from the box exceeded the then maximum for point rodding.
JimS
By back calculation from the signalling notices on oban-line, I have the two points 250 and 270m from the signal box, ie too far away to work. Sorry about the metrication, but over 280 yards.

regards
Bill
(a new person !)
Jim Summers
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Re: Yellow drop flap signals

Post by Jim Summers »

Welcome, Bill.
Another one interested in the Oban line cannot be a bad thing!

JimS
Bill_Gensheet
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Joined: Sat Nov 03, 2018 7:34 pm

Re: Yellow drop flap signals

Post by Bill_Gensheet »

Thanks for the welcome Jim.
Some may have come across me from Gensheet (UK service train diversions, rare track workings) or the Scot-Rail email group. I am mostly down in Essex, but also up in Perthshire a fair bit.

My Killin Jn visit in 2007, since everyone has to go there once....
http://www.gensheet.co.uk/photo8/KillinJn/index.htm

I am working on a project (not models) for the lines Gleneagles / Perth / Dunblane - Oban / Ballachulish, so i expect that will generate a load of questions. I'll be getting the back issue CD and going through those first though.

regards
Bill
jasp
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Joined: Mon Aug 20, 2012 5:40 pm

Re: Yellow drop flap signals

Post by jasp »

Welcome also from me. I hope you enjoy your membership.
Good to see your photos around Killin Jct. Jim Summers has a developing layoutbased thereupon.
The CRA had an outing to parts of the C&O some years ago which included Lochearnhead, Glenogle and Killin and junction. There was a bit more infrastructure then, including staff cottages.
Jim P
Chairman
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