Gantry Mounted signal boxes

[Graeme Leary]

Having just acquired a copy of C J Freezer's 'Model Railway Signalling' I see I should probably add a signal box at the opposite end of the main station (depicting a major mainline station, where I already have one placed at one end alongside the tracks just before entering the platform). This would give me a (say) West and North - or East and West - as Mr Freezer suggests.

Space alongside the tracks at the other end is limited so I plan to mount the box (a Metcalfe kit suitably repainted) on a gantry over the 4 tracks (2 stopping and 2 through) that are between the platforms. (There are additional points before the platforms leading to sidings and an 'outside' through line) However, at that point a slight gradient and a slight curve begins and as I plan eventually to install Will's rodding kits I wonder if signal boxes were installed in a similar situation or only on 'level' ground so rodding could be fitted or were adjustments made to allow for 'slight' gradients. Various photos I've googled indicate overtrack signal boxes only show them on flat levels but were there exceptions such as this?

And, if this is prototypically correct I'd be grateful for any suggestions on how the Wills rodding kits should be fitted from the overhead gantry box down to the adjacent points. From a technical perspective were 90 degree 'joints' fitted where the rodding first came horizontally out of the box, turned 90 degrees and continued horizontally until the end of the gantry and then another 90 degree angle/joint vertically down to the ground and then another where it continued on the ground to the points it was controlling? (Hope this makes sense).

Many thanks, any suggestions much appreciated.

Graeme Leary
New Zealand

[Mickey]

I believe there was a few gantry mounted signal boxes on the North Eastern around the Newcastle area and maybe elsewhere around the north east also I believe there may have been a few on former LNWR/LMS lines at a few places around the north west as well although I can't think of any on the GNR/LNER main line?.

[Graeme Leary]

Thanks Mickey. I think the one you're referring to is/was near Hexham and there are plenty of good shots on 'Gantry Mounted Signal Boxes British Railways' but none showing on any sort of gradient hence my query. Might have to employ some modeller's license but hope to be as accurate as possible (particularly when I start fitting the rodding).
Graeme

[John Palmer]

Another North Eastern box mounted on a gantry and, I think, still extant can be found at Wylam. Typically, these North Eastern boxes on gantries were constructed to one side of the gantry with the frame aligned parallel to the tracks, so that the rodding could be carried directly to ground level from the lever tails with no horizontal run at gantry level. In the case of signal controls, however, it's clear that some of the wires at Hexham were carried horizontally across the gantry to the support beam furthet from the box before being carried over pulleys and then downwards to ground level.

Gantry boxes having frames at right angles to the track were not unknown; examples include Clapham Junction and Canterbury West, and the massive installation at Waterloo 'A' box utilising a Stevens tappet-locked frame that was ultimately extended in 1911 to include 250 levers.

I wouldn't expect gradients to be a significant consideration affecting the decision on whether to install a box on a gantry. After all, the rodding from the majority of conventional boxes includes initial vertical lengths of rod from the lever tails, so the fact that a box has been mounted on a gantry doesn't necessarily set it apart from other boxes so far as the rod runs are concerned. In all cases, however, you have to design your rod runs in such a way as to equalise in any run the length of rodding that is 'pushed' with the amount that is 'pulled' in order to mitigate the extent to which temperature changes and resulting contraction/expansion of the rodding alter its length and thus the 'at rest' position of the apparatus it controls. Sometimes this can be achieved through the arrangement of cranks in the run, at other times compensators must be inserted into the run for this purpose.

I've seen some attractive installations of the Wills rodding but understand it to be somewhat overscale, to the extent that it would be near correct size on an S gauge layout rather than one in 4mm : 1'. If that's a concern then you might want to take a look at alternative suppliers of rodding components. Ambis Engineering and Roxey Moulding's Southwark Bridge range are two that spring to mind.

[JonBates]

Hi Graeme

There is the NER signal box near Whitby - it is an overhead box and one line underneath it is on an incline. See link below for a photo.

Jon

http://www.time-capsules.co.uk/picture/ ... Signal-Box

[lar1976]

Not forgetting the boxes at Belford and Forest Hall on the ECML north of Newcastle and also the box at the north end of Newcastle Central itself.

[nzpaul]

Hi Graeme
Google Portobello East signal box, I think it nails the breif quite well. Fairly large gantry box, and the ECML goes under it, around it....looks to be a busy place. Two good photos on the Railscot site.

Cheers
Paul

[Graeme Leary]

Many thanks all for the very good references/links.

Also for the background comments too John - makes sense and explains the 'off centre' boxes I've seen photos of and with frames in these at right angles and - therefore I presume - cables having direct connection down to the ground level rodding. This should suit my scenario very well as I can build a gantry that covers all through/stopping tracks plus the sidings that could be controlled from the one box. I will have another look to check that the Wills kit scale looks acceptable.

Paul - might be down your way during Labour Weekend - will get in touch.

Graeme

[Bunkerbarge]

There used to be one at Peterborough East, as per the first two shots and two at Canterbury both East and West.

[StevieG]

Wondering if you have one thing slightly confused in mentioning 'cables down to ground level rodding' Graeme Leary.
Mechanical point connections must be of crank-connected rodding throughout* owing to the push and pull nature of points operation in the UK.
Signal wires (the cables you refer to?) are tensioned by the pulling of their levers to pull signals to 'Clear', and the wires basically are pulled back by signal counter weights when the tension is released, and so can be run over pulleys where a change of direction is needed.

* - (just to say for completeness that the double-wire [pull-and-'push', basically a loop] system, for points and signals, very popular in Europe, could once also be found in the UK but was very rare indeed here.)

[Mickey]

(just to say for completeness that the double-wire [pull-and-'push', basically a loop] system, for points and signals, very popular in Europe, could once also be found in the UK but was very rare indeed here.)

Just to deviate slightly off the main topic thread regarding 'double wire' signals I actually recall seeing many double wire semaphore signals in use when I was travelling in the Sudan (north Africa) in 1978 on a run down from some way station in the middle of nowhere (maybe 50 miles south west of Port Sudan?) down towards a town called Atbara on or near the river Nile?. Also as a side observation there was also a 0-6-0 tank loco 'in steam' acting as the station pilot at Atbara on that same journey.

Below the picture claims to be of Atbara railway station(?) but that's not how I remember it although the picture looks more like the yard & sidings at Atbara?.

https://en.wikipedia.org/wiki/Atbara#/m ... ailway.jpg

Back to the topic thread regarding 'gantry mounted signal boxes' one box that does comes to my mind but was a little bit before my time was Kensington Middle box on the west London line which I believe was originally a LNWR box but was closed during the 1950s I believe?.

The southern Railway & southern region inherited a small number of gantry mounted boxes from the pre=grouping companies I believe.

[Graeme Leary]

Thanks again all,

Bunkerbarge - I will do something that closely resembles the Canterbury (East??) box on the gantry across the tracks but with the box set off to one side. Under the gantry I have 6 tracks 'reducing' (terminology ???) to 3 points and the overall width is approx 25mm so that should suit nicely).

Stevie; yes you're right, was confused about the (a) terminology and (b) the mechanics so a lot wiser now. In my scenario John Palmer's earlier posting sums up what should work , ie as he notes in Hexham which had horizontal wires running across to pulleys and then down to the ground where I presume after going around another set/s of pulleys they would be connected to the rodding. Haven't many photos to refer to see close up examples of this but no doubt should be able to google some.

Mickey - your reference to Southern Railways opens up another, possibly confusing issue for a LNER modeller. I have seen odd references to different styles of general architecture and presume there was much variation in the 'Big 4", let alone the many constituents that made them up before grouping. However, not going to get bogged down in that detail as well!

Graeme

[StevieG]

Graeme Leary, I am still not convinced that you have a clear understanding of some mechanical connections.
I have re-read John Palmer's comments on this, and as I don't think that Hexham was unconventional in these respects (i.e. it did not double-wire-worked equipment), the wires that he refers to as first going across and then down via pulleys, would be signal-operating wires (cables as you may prefer it).
And so as I said, rodding for points (&c, such as detonator placers, facing point locks, switch diamonds, level crossing gates' apparatus, mechanical releases to ground frames or other signal boxes, scotch blocks and derailers, swing bridge apparatus, turntable bolts) would be of 'rigid' rodding throughout, from lever to its function (no wires involved), any changes of direction (horizontal or vertical) being achieved via cranks.
Your ground level rodding is only for points operation ?

[John Palmer]

In case my previous post was the source of any confusion, here's an enlarged extract from a shot that can be found at https://hiveminer.com/Tags/class142%2Chexham/Timeline, which I have annotated to show the signal wire pulley wheels to which I was referring.

So far as I can tell, the pulleys were, at the date this photograph was taken, still performing their designed function of carrying single wire signal connections from the elevated frame to ground level.

[Graeme Leary]

Thanks again John. Couple of points you might have some further thoughts on (and apologies for any incorrect terminology):-

The pulleys appear to be set back slightly from the front edge of the gantry so presume the cable came out of the box from the lever frame which would have been positioned for the signalman to face along the gantry ie across and with the tracks either side, with no change of horizontal direction of the cables necessary ie as in a ground situated signalbox the tracks were either side of the front of the box.

(Also assume the levers were connected to cables (rather than rigid rods) as they left the box to allow the 90 degree 'drop' turn at the pulleys and then connected to 'rigid' rodding when they reach the ground.

The other shot (on the link) doesn't show any rodding on the ground so presume it heads away (to the other side of the box/gantry) and then works the points to the 2 tracks on the left side of the shot.

(Bit hard to put into words).

Graeme