GNR Signals

[strang steel]

If you get stuck, or want further advice please feel free to contact me.

Yes, I do need advice. Some of the brass components on the fret are tiny and very close together. What is the best tool to use to cut them from the fret without bending everything out of shape?

[StevieG]

Here are two shots of mine of a Somersault signal.
Both at same location.

Any guesses as to where?

Don't know where Bryan - I'm not even sure of their design/company.

Pardon me for mentioning please, but although the small arm is pivoted centrally, the main arm looks to not to be, appearing to be pivoted near the right-hand end, at the side of the post; - and both arms have their spectacle glasses built as part of the arms, so I've a feeling that most signalling historians wouldn't regard these as true 'somersaults'. Have you a definite reason for referring to them as such?

They do look nice though, and it's good that they have been recorded. Thanks v.m. for sharing.

[61070]

Interesting, 61070.
I had never heard of, noticed, or even thought of, dffering arm thickness as a means of ensuring 'fail-safe' return to Danger.
One thought though, however unlikely a risk it might've been. Given that the theoretical proper 'off' indication, as in drawings, was the arm fully vertical, I wonder if with weight distribution alone (pivot not offset), there would have been an outside slim chance of mechanism failure with an arm in such a position, leaving the arm there, finely balanced in the complete 'off' position.

My guess would be that the pivot was always offset, or perhaps soon became so if trials led to realisation of the above possibility, but perhaps at some time supplemented by a thicker, thus heavier, right-hand end as well.

Having given the mechanics of this some thought, I think it's possible that both the above centreline pivot and a thicker/heavier back end would work together as a cleverly designed dual return to danger (ie horizontal) 'fail-safe' mechanism. This is hard to explain without diagrams but I'll have a go.

Considering each effect on its own, the above centreline pivot provides its greatest 'returning moment' when the arm is fully vertical and 'off'; but its effect diminshes as the angle of the arm decreases, reaching zero as the arm becomes horizotal or 'on'. Conversely, the effect of the thicker/heavier back end alone is zero when the arm is fully vertical, as you say, but it increases as the arm angle decreases, reaching its maximum at the horizontal position. With careful design, by combining the off-centreline pivot and a suitable rate of taper of the arm, a constant returning effect could be achieved so as to bring the arm firmly horizontal against its 'stop' if the linkage failed; I seem to remember that there was a mechanical stop of some kind so that the arm was prevented from rotating past horizontal. Exactly how this worked I can't recall though; it might have been incorporated into the spectacle frame's pivoting arrangement.

I have an idea where 'my' old signal arm might be these days so, if I can track it down, I'll ask for some measurements and/or photos. Sadly I had to pass it on when the former family home, in whose garage it resided, was sold in the 1990s. We'd acquired it in the late 1960s from the S&T Engineers at Grantham, and I believe it had come from the Stathern Junction area of the former GN and L&NW Joint line.

[micknich2003]

If you get stuck, or want further advice please feel free to contact me.

Yes, I do need advice. Some of the brass components on the fret are tiny and very close together. What is the best tool to use to cut them from the fret without bending everything out of shape?

Use a sharp modelling knife, and then carefully clean up the part with a needle file or wet and dry paper. Mick.

[micknich2003]

I have checked drawings of several railway company's wooden signal arms, it appears to be standard practice for an arm to taper in thickness towards the extreme end. Mick.

[micknich2003]

Pardon me for mentioning please, but although the small arm is pivoted centrally, the main arm looks to not to be, appearing to be pivoted near the right-hand end, at the side of the post; - and both arms have their spectacle glasses built as part of the arms, so I've a feeling that most signalling historians wouldn't regard these as true 'somersaults'. Have you a definite reason for referring to them as such?

Not Somersaults, more remenisant of GW "Centre Balanced" arms, but still interesting pictures, and thanks for sharing. Mick.

[StevieG]

Interesting, 61070.
I had never heard of, noticed, or even thought of, dffering arm thickness as a means of ensuring 'fail-safe' return to Danger.
One thought though, however unlikely a risk it might've been. Given that the theoretical proper 'off' indication, as in drawings, was the arm fully vertical, I wonder if with weight distribution alone (pivot not offset), there would have been an outside slim chance of mechanism failure with an arm in such a position, leaving the arm there, finely balanced in the complete 'off' position.

My guess would be that the pivot was always offset, or perhaps soon became so if trials led to realisation of the above possibility, but perhaps at some time supplemented by a thicker, thus heavier, right-hand end as well.

Having given the mechanics of this some thought, I think it's possible that both the above centreline pivot and a thicker/heavier back end would work together as a cleverly designed dual return to danger (ie horizontal) 'fail-safe' mechanism. This is hard to explain without diagrams but I'll have a go.

Considering each effect on its own, the above centreline pivot provides its greatest 'returning moment' when the arm is fully vertical and 'off'; but its effect diminshes as the angle of the arm decreases, reaching zero as the arm becomes horizotal or 'on'. Conversely, the effect of the thicker/heavier back end alone is zero when the arm is fully vertical, as you say, but it increases as the arm angle decreases, reaching its maximum at the horizontal position. With careful design, by combining the off-centreline pivot and a suitable rate of taper of the arm, a constant returning effect could be achieved so as to bring the arm firmly horizontal against its 'stop' if the linkage failed; I seem to remember that there was a mechanical stop of some kind so that the arm was prevented from rotating past horizontal. Exactly how this worked I can't recall though; it might have been incorporated into the spectacle frame's pivoting arrangement.

I have an idea where 'my' old signal arm might be these days so, if I can track it down, I'll ask for some measurements and/or photos. Sadly I had to pass it on when the former family home, in whose garage it resided, was sold in the 1990s. We'd acquired it in the late 1960s from the S&T Engineers at Grantham, and I believe it had come from the Stathern Junction area of the former GN and L&NW Joint line.

I appreciate, understand and agree with your thoughts on this; thank you.

As regards a 'stop' to prevent the arm going beyond the horizontal, presumably its effectiveness could be subject to wear over time, hence the latterly common sight of well-used arms sitting with their left-hand ends slightly above (about 5 degrees?) the horizontal when at 'Danger'.

[strang steel]

If you get stuck, or want further advice please feel free to contact me.

Yes, I do need advice. Some of the brass components on the fret are tiny and very close together. What is the best tool to use to cut them from the fret without bending everything out of shape?

Use a sharp modelling knife, and then carefully clean up the part with a needle file or wet and dry paper. Mick.

Thanks very much Mick.

I will try that, but with my cow-udder-fingers some of these parts sow seeds of terror when I think of trying to work with them.

[Bryan]

Pardon me for mentioning please, but although the small arm is pivoted centrally, the main arm looks to not to be, appearing to be pivoted near the right-hand end, at the side of the post; - and both arms have their spectacle glasses built as part of the arms, so I've a feeling that most signalling historians wouldn't regard these as true 'somersaults'. Have you a definite reason for referring to them as such?

Not Somersaults, more remenisant of GW "Centre Balanced" arms, but still interesting pictures, and thanks for sharing. Mick.

Mick and Steve.
The origin of the signal was from Liverpool Riverside station and was photographed at Steamport Southport in the late 70s as that would be when 44806 was resident and in steam (just due to backhead crack).
However since the closure of Steamport and the subsequent move to Preston I do not know if the signal has survived.

[john coffin]

I must confess to being somewhat amazed that no one has mentioned the book "An Illustrated History of Great Northern Signalling" by Michael Vanns. It does seem to be still available via the great big A/

Paul

[strang steel]

I do have that book, but have not looked at it for a while so thanks for the prompt. It does have some interesting photos of various signals, but also many of block instruments and lever frames.

On a slight tangent. I visited the NNR at the weekend for their spring gala, and the railway has a number of working somersault signals at the stations, including one just outside Weybourne which also has an illuminated platform number indicator attached.

[Mickey]

Deleted

[strang steel]

Two more questions folks.

I have some whitemetal "concrete" signal posts. Has anyone a recommendation of the closest paint colour to weathered concrete signal post shade? Or maybe I should just mix various stone shades and light brown and come up with something?

Also, what do people use for representation of the coloured glass in the spectacle plate?

[Mickey]

Deleted

[strang steel]

Thanks Micky.

I know there were posts with different arrangements of holes, and I dont remember seeing many pear shaped ones in Lincolnshire although looking at photos there were some.

It is not surprising that I am used to the ex-GNR type with straight sides and curved tops and bottoms, because they had probably been in situ for over 80 years by the time that I saw them.

Anyway, the MSE ones that I have seem to be the GNR style although the holes would seem to be upside-down (this is not a joke), with more at the bottom than the top. Most of the posts that I remember had more holes towards the top - an example being this one at Lincoln, three photos down the page:-

http://www.roscalen.com/signals/Lincoln/WestHolmes.htm

However, I am not too worried about the details as long as the signal looks the part, because there were all manner of combinations, especially with brackets. Some were all concrete including the dolls, others had lattice dolls and a main concrete post, and others were either all lattice or all wooden - with no doubt, a few combinations of any or all of those.