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Signal post access platforms

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Signal post access platforms

Unread postby Don Newnham » Fri Sep 2, 2016 9:39 pm

On the L&BR we are now constructing semaphore signal posts for our (hopefully soon) extension. On one of these posts are two semaphore arms, vertically one over the other. No problems fixing the arm pivot casings, lamp brackets or counterbalance. The distance between the two arms is 5'.

However, this week we intended to attach the access platforms, only to find that wherever we positioned them on the posts, either the platform or the guardrail fouled on a previously fitted casting. I wonder if both counterweights should be repositioned below the lowest signal thereby gaining more space in which to attach the platforms.

Where there any 'Standards' on this issue or was it as with most signalling equipment - made to fit the situation?
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Re: Signal post access platforms

Unread postby Adrian Crafer » Sat Sep 3, 2016 6:27 pm

Don Newnham wrote: I wonder if both counterweights should be repositioned below the lowest signal thereby gaining more space in which to attach the platforms.

Where there any 'Standards' on this issue or was it as with most signalling equipment - made to fit the situation?


I cannot speak for the L&BR signalling practice, but in all versions of drawings I have for various signal and railway companies I have to hand, where a signal has multiple arms, the counterbalance weight arms are mounted on a single casting. That casting is designed to accomodate the appropriate number of counterbalance arms along with, if appropriate, any slotting. Such an arrangement being normally towards the lower part of the post, and obviously as a result clear of the ladder and any stages.

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Re: Signal post access platforms

Unread postby Chris Osment » Sat Sep 3, 2016 7:24 pm

From what little I can glean from web photos, the relevant L&B 'new work' is using SR-style rail-built posts. Apart from the usual stop+lower distant arm arrangements, the only SR example with two non-co-acting stop arms that immediately comes to mind is the former Exeter Central 'A' Nos 2 and 3 at the end of the Up platform there. This had separate weight lever assemblies. Admittedly it was a lattice post, but that ought not to make any difference?

There is quite a good view of the rear of that signal on page 200 of the Irwell Press "Main Line to the West: Vol 3", which might be worth a study by the OP.

I suspect it may well prove a case of 'jiggle to fit' :wink:
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Re: Signal post access platforms

Unread postby davidwoodcock » Sun Sep 4, 2016 9:20 am

There was another SR example of two non-co-acting stop arms on the same post - Ventnor West on the Isle of Wight, which was probably altered to that arrangement during the winter of 1924/25 after the introduction of pull-and-push working on the branch. The post here was wooden, and fairly short despite the fact that there was a third arm permitting direct entry into the goods yard, and only a single access platform was provided - for the uppermost of the two LQ homes.

SR co-acting stop arms invariably(?) had separate platforms and balance weights, etc but, of course, there was plenty of space available. What is perhaps more interesting is that generally SR home-plus-subsidiary on the same post signals used a single balance weight fitting for the two arms. I couldn't quickly find a photo of a rail-built post with such an arrangement but they must have existed in some numbers and, if you continue to have problems, I suspect that copying the arrangements on such a post would provide an authentic answer.

With so few examples of the real thing, I doubt whether there were any laid down standards and each installation would have been treated pragmatically. The District Engineer, Exeter, was somewhat notorious for doing his own thing anyway.
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Re: Signal post access platforms

Unread postby davidwoodcock » Sun Sep 4, 2016 11:37 am

I should have added that there are excellent photos of the both front and rear of the Ventnor West signal on pp 77-79 of Peter Paye's book "The Ventnor West Branch". There is also a (less clear) photo of the rear of the signal on this web page https://chasewaterstuff.wordpress.com/tag/isle-of-wight/ (scroll down).
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Re: Signal post access platforms

Unread postby Don Newnham » Sun Sep 4, 2016 6:18 pm

In the various intricacies of railway signalling an access platform seems -dare I say - a simple thing but as we are,as always, still learning so my thanks to our three colleagues for their suggestions.

We do have a double crank casting hidden away in the depths of Exmoor, now to find it.

Re the rail posts,- whilst we all prefer to have Heritage Railways that look authentic, that nasty money thing crops up; decision here made to use well worn rails for new posts; they are well worn,- very sharp burr along the top edges!

Thanks, Don
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Re: Signal post access platforms

Unread postby Chris Osment » Sun Sep 4, 2016 7:19 pm

Nothing "un-heritage" about rail-built posts - not only did the SR provide quite a few on the L&BR, but the S&DJR were using the same material (but to a different design) almost certainly by the mid-1890s :-)
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Re: Signal post access platforms

Unread postby davidwoodcock » Sun Sep 4, 2016 8:01 pm

I second Chris on this one. It seems probable, had the L&BR managed to survive until, say, the Beeching Report, that almost all of the signals would have been UQ on rail-built posts, much like the Isle of Wight, in fact.
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Re: Signal post access platforms

Unread postby Chris Osment » Sun Sep 4, 2016 8:20 pm

davidwoodcock wrote:I second Chris on this one. It seems probable, had the L&BR managed to survive until, say, the Beeching Report, that almost all of the signals would have been UQ on rail-built posts, much like the Isle of Wight, in fact.


I'm not so sure.....

By the time that the line closed most (but by no means all) of the wooden posts had been replaced by the SR with lattice or rail (or concrete) posts, all - with one exception - with LQ arms. Whilst they may have then gone on to replace the remaining wooden posts, and probably with rail-built examples, they might well have reused lattice posts from elsewhere (if the S&DJR could be taken as an example of that mixed practice). No doubt all the new arms post-1935 would have been UQ, but......given the number of examples of rail-built signals with LQ arms from the late-1920s which survived in the South West until the 1960s, would they have bothered to spend more money to retro-fit new UQ arms and fitments to existing LQ examples on the L&BR???

Incidentally, it occurs to me that the OP did not state whether the new signals would be LQ or UQ arms - I had somehow assumed the latter, but maybe that is not the case?
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Re: Signal post access platforms

Unread postby davidwoodcock » Mon Sep 5, 2016 8:27 am

I agree that I would not have expected those signals whose wooden posts had already been replaced by lattice or concrete posts to have had them replaced again by rail-built posts - unless the post was damaged or the signal had to be moved.

However, I believe that, once rail-built posts were introduced, they were very much the preferred choice for any short post that needed replacement - and I believe that the majority of L&BR posts were short. I don't know whether the S&DJR was an exception (not exactly unusual) or whether it was taller posts there that were replaced by secondhand (or even new?) lattice posts. I suspect that any short secondhand lattice posts in good condition were stored for potential use on gantries where using rail wasn't an option.

As to replacing LQ with UQ, Chris is probably right, BR(S) does seem to have had a deliberate policy of renewing with UQ arms during the 1950s (although the task was never completed), but, of course, the L&BR, had it survived, would have been under WR S&T control at the time!
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Re: Signal post access platforms

Unread postby RichardH » Mon Sep 5, 2016 9:10 am

I would have thought LQ as they seem to have standardised on that, but obviously photographic evidence is much rarer.

A UQ example at Shanklin appears to show the use of a double lever casting, but when space for the downrods was an issue the subsidiary arm could be driven on the rear of the post with a mirror-image balance lever mounted behind the front one (Worthing on page 4), but obviously only for UQ.

http://www.semgonline.com/proto/semaphore_03.html
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Re: Signal post access platforms

Unread postby JRB » Mon Sep 5, 2016 10:29 am

davidwoodcock wrote:.............. the L&BR, had it survived, would have been under WR S&T control at the time!

So follow V of R practice. Hmmm.
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Re: Signal post access platforms

Unread postby davidwoodcock » Mon Sep 5, 2016 11:05 am

JRB wrote:
davidwoodcock wrote:.............. the L&BR, had it survived, would have been under WR S&T control at the time!

So follow V of R practice. Hmmm.


Quite an interesting thought, although the operating stayed with the SR so no exchange of locos or stock (even had that been possible).
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