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Tyesley South - VoL switch?

British signalling of the past (UK, excepting Northern Ireland)

Tyesley South - VoL switch?

Unread postby RDNA » Thu Apr 5, 2018 8:55 pm

Can anyone comment on this flickr photo?

https://www.flickr.com/photos/geoffsimages/27385610598

I have guessed at a 'Vehicle on Line' switch in the comments - but were these provided at Tyesley?

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Re: Tyesley South - VoL switch?

Unread postby GarthTilt » Sat Apr 7, 2018 10:43 am

There were 3 vehicle on line switches at Tyseley Station. Up Main TC TN36T; Up Relief TC TN29T; Down Relief TC TN9AT. They are shown on a locking sketch for Tyseley South drawn 19 March 1935 with an issuing date stamp from SEO Reading 'AUG 8 1956'.
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Re: Tyesley South - VoL switch?

Unread postby RDNA » Sat Apr 7, 2018 12:28 pm

GarthTilt wrote:There were 3 vehicle on line switches at Tyseley Station. Up Main TC TN36T; Up Relief TC TN29T; Down Relief TC TN9AT. They are shown on a locking sketch for Tyseley South drawn 19 March 1935 with an issuing date stamp from SEO Reading 'AUG 8 1956'.


Thanks very much for that Garth,

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Re: Tyesley South - VoL switch?

Unread postby Mike Hodgson » Sat Apr 7, 2018 7:22 pm

I have not heard much mention about VoL switches - I thought they tended to be used in places like platform stop blocks where TCs would be especially unreliable because of dirty rails. Their importance would seem gtreater on through lines like Tyseley where train speeds would be higher. How common were these switches? I haven 't heard of any accidents caused by platform staff neglecting to operate them, yet the concept seems to be highly susceptible to human error. Of course it may be that in practice accideints didn't happen because either the vehicles usually did drop the track circuits anyway, or the signalman's experience of the timetable averted any such oversight.
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Re: Tyesley South - VoL switch?

Unread postby davidwoodcock » Sat Apr 7, 2018 7:30 pm

Mike Hodgson wrote:I have not heard much mention about VoL switches - I thought they tended to be used in places like platform stop blocks where TCs would be especially unreliable because of dirty rails. Their importance would seem gtreater on through lines like Tyseley where train speeds would be higher. How common were these switches? I haven 't heard of any accidents caused by platform staff neglecting to operate them, yet the concept seems to be highly susceptible to human error. Of course it may be that in practice accideints didn't happen because either the vehicles usually did drop the track circuits anyway, or the signalman's experience of the timetable averted any such oversight.


.... and the use of reminder appliances on the relevant signal levers.
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Re: Tyesley South - VoL switch?

Unread postby Mark Lamb » Sat Apr 7, 2018 8:27 pm

I don't know much about VoL switches - I never met one in my work - but I always thought VoL switches were for use where there weren't any track circuits, and the section of track in question was not in sight of the signaller. e.g. - as above - by buffer stops. The last place I saw one in use was at Kyle of Lochalsh in the 1970's. As I recall from catalogues of blockshelf indicators, the VoL indicator was quite different from the TC indicator (and presumably meant the signaller interpreted it differently too).

Electrical depression bars (later superceded by eutectic strips welded onto the rail head) were for use in conjunction with track circuits next to buffer stops, where dirty rail (or a build of rust between the wheel of a vehicle that hasn't moved in ages and the rail head) could cause the track circuit to show clear when occupied.

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Re: Tyesley South - VoL switch?

Unread postby John Hinson » Sun Apr 8, 2018 5:35 am

Mark Lamb wrote:I don't know much about VoL switches - I never met one in my work - but I always thought VoL switches were for use where there weren't any track circuits, and the section of track in question was not in sight of the signaller. e.g. - as above - by buffer stops. The last place I saw one in use was at Kyle of Lochalsh in the 1970's. As I recall from catalogues of blockshelf indicators, the VoL indicator was quite different from the TC indicator (and presumably meant the signaller interpreted it differently too).

VOL switches often worked in conjunction with track circuits to allow for the detaching of odd vehicles (such as four-wheel vans) from trains which might not have been sufficient to show on track-circuits. It may even have been in early days that such vehicles were physically not track-circuit compatible.

The need for them significantly reduced in more recent years as neither circumstances existed in most cases.

They would be operated by the shunter before climbing down to detach.

Note that at Tyseley there were three, specifically on the lines with track circuits and with no provision on the fourth line which did not.

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Re: Tyesley South - VoL switch?

Unread postby davidwoodcock » Sun Apr 8, 2018 8:10 am

John Hinson wrote:VOL switches often worked in conjunction with track circuits to allow for the detaching of odd vehicles (such as four-wheel vans) from trains which might not have been sufficient to show on track-circuits. It may even have been in early days that such vehicles were physically not track-circuit compatible.


Not just the early days. Photographic evidence shows that odd vehicles retained (wood centred) Mansell wheels even into BR days and these were often vehicles such as horse boxes which were likely candidates for en route detachment.
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Re: Tyesley South - VoL switch?

Unread postby Mike Hodgson » Sun Apr 8, 2018 8:43 am

Mansell wheels didn't necessarily mean they wouldn't conduct electricity as some vehicles had their tyres bonded to the axles in order specifically to overcome the problem. Unfortunately this isn't fail-safe, because nobody's going to notice damage to the bonding in the ordinary course of events.

I seem to recall reading somewhere an instruction to the effect that stock with Mansell wheels should not be mrshalled as last vehicle because of the risk in TCB areas if the train were to divide (and presumably the continuous brake would also have to fail).
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Re: Tyesley South - VoL switch?

Unread postby RDNA » Sun Apr 8, 2018 9:21 am

To relate my recollection of VoL switches, until the late 1960s there was one for the down platform at Hinckley, Leicestershire. It was in a glass fronted wooden case located under a narrow arch in the abutment of a public footbridge which crossed the station. The line was not track circuited and 'Line Clear' releases were not provided at that time. The switch simply worked an indicator in the box and held the block needle at TOL.

My other memory is that they were provided at each end of Leicester London Road platforms, in that case working indicators in East and West station boxes and holding the track circuit indicators at 'Occupied'. There were no block instruments provided.

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Re: Tyesley South - VoL switch?

Unread postby John Hinson » Sun Apr 8, 2018 9:22 am

Mike Hodgson wrote:I seem to recall reading somewhere an instruction to the effect that stock with Mansell wheels should not be mrshalled as last vehicle because of the risk in TCB areas if the train were to divide (and presumably the continuous brake would also have to fail).

Not really - you are totally focussed on trains being divided when the real issue is being clear of points etc when they are operated.

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Re: Tyesley South - VoL switch?

Unread postby John Prytherch » Tue Apr 10, 2018 11:15 pm

Whitchurch (Salop) had at least one VoL switch and I guess there was one for each of the three through platforms, as I expect quite a number of vans were exchanged between Shrewsbury and Crewe trains and those on the Cambrian and / or the Chester branch. I remember, as a child, reading the explanatory notice beside it, before I understood anything about the block system!

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Re: Tyesley South - VoL switch?

Unread postby Mike Hodgson » Wed Apr 11, 2018 8:52 pm

Was Tyseley by any chance one of the places they slipped coaches?
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Re: Tyesley South - VoL switch?

Unread postby JRB » Wed Apr 11, 2018 10:10 pm

Certainly not in recent years. Not much more than Reading Gen. & Bicester for a long while.
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