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No 7 and Auxiliary Tablet Instruments.

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

No 7 and Auxiliary Tablet Instruments.

Unread postby MRFS » Thu Mar 10, 2011 4:34 pm

Rather than dilute the discussion on Instrument Colours HERE - I've found some circuit diagrams, and some marketing puff from Tyers on Auxiliary Tablet Instruments.

It's amazing what you can find squirrelled away under your bed (and forgotten what you had!); unfortunately the Tyer's puff doesn't have the accompanying circuit diagram, but I think the technical description of what is there will suffice for most people - I will scan and put up the links via Picasa shortly, so you can see the relevant information. Needless to say, I haven't been out shopping yet (as I hinted at in the other thread), but this is far more interesting. Watch this space.
  • No 7 Tablet Instruments
    • Overview of Single Instrument LINK
    • Two Instruments, No Intermediate, earth return LINK
    • Two Instruments, Intermediate release by TC occupation, earth return LINK
  • Auxiliary Tablet Instruments

As I've said before the advantage of Picasa is that you can relatively easily zoom into the pictures - magnifying glass top right and +/- buttons top left when zoomed in.

Going on the description on page 1 the top slide is used, and something akin to the tumbler illustrated in the other thread:

Image

for the indexing of tablets inserted. It seems too from the marketing puff that this was suitable for No 6 tablet instruments, if so then I suggest the same style of auxiliary was used for both No 6 and No 7 instruments, using a No 7 carcass.

Very Interesting - can we find a No 6 installation anywhere?
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Re: No 7 and Auxiliary Tablet Instruments.

Unread postby Chris Osment » Thu Mar 10, 2011 7:16 pm

Many thanks - all very interesting.

So, referring to the info re auxiliary instruments, where is the "3-position hand operated switch on the signal cabin instrument" then? I wonder if that is what I reckon can be seen sticking out of the front?

The only point to note about using this type of instrument with a No 6 circuit is that of course the tablets are different sizes, so there would have be modifications to the slides.
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Re: No 7 and Auxiliary Tablet Instruments.

Unread postby MRFS » Thu Mar 10, 2011 7:35 pm

Chris Osment wrote:So, referring to the info re auxiliary instruments, where is the "3-position hand operated switch on the signal cabin instrument" then? I wonder if that is what I reckon can be seen sticking out of the front?


BINGO! Looking at the two pictures (colour and b&w) that we have from different directions, it would look to be possibly a three position switch, photographed in both cases in the central position, but able to swing left or right.

Chris Osment wrote:The only point to note about using this type of instrument with a No 6 circuit is that of course the tablets are different sizes, so there would have be modifications to the slides.


Yes - I guess that the magazines would be altered, and there must have been plenty of metal in the slides to allow for alterations.
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Re: No 7 and Auxiliary Tablet Instruments.

Unread postby Alan Johnston » Fri Mar 11, 2011 9:57 am

Very interesting indeed, pity we haven't a photo of the platform instrument, from your description it would have had an indicator but not the switch. I will try and scan my negative a bit closer and see if we can confirm the legend on the plate around the switch. That will need to be later as I have the PC in bits at the moment ..... :roll:

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Re: No 7 and Auxiliary Tablet Instruments.

Unread postby Alan Johnston » Sun Mar 13, 2011 2:53 pm

As promised I zoomed in my old B&W negative of Muir of Ord and you can see the switch as expected!

Image

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Last edited by Alan Johnston on Sat Oct 28, 2017 1:20 pm, edited 1 time in total.
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Re: No 7 and Auxiliary Tablet Instruments.

Unread postby MRFS » Sun Mar 13, 2011 4:04 pm

MAGNIFICENT

Thank-you very much.
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Re: No 7 and Auxiliary Tablet Instruments.

Unread postby MRFS » Tue Jun 7, 2011 10:14 pm

I have a little corollary to this discussion - perhaps it should be in 'Overseas', but it is germane to the No 7 Auxiliaries. If we go to NZ, I suppose the 'home' of No 7 Tablet instruments there were installations called 'Tablet Transmitters', not as you may think intermediate instruments, but seemingly an auxiliary pair to an intermediate siding.

Consider a section: Lovells Flat - [Stirling] - Balclutha. Lovells Flat and Balclutha are terminal instruments, there is a pair of 'tablet transmitters' between Stirling and Balclutha. The 1974 operating instructions read:

a) A tablet is obtained from either Lovells Flat or Balclutha for the Lovells Flat - Balclutha section, using bell signal Release Tablet for Shunting (5-2), followed by the usual Train Departure (2) signal.

b) On arrival at Stirling the driver gives the guard the tablet, which unlocks the points. The guard then puts the tablet in the top slide of the tablet transmitter instrument S, closes up the instrument and sends
Train Arrival (3) to Balclutha (where the other tablet transmitter is located).

c) Balclutha closes up his tablet transmitter B2, and then requests the guard at Stirling permission to release a tablet from B2 by sending the special bell signal
Transmit Tablet (4-2). He then inserts the tablet from B2 into B1 and sends Shunting completed, Tablet replaced (2-5) to Lovells Flat. After Lovells Flat has closed his instrument, ordinary tablet working can be resumed through the Lovells Flat - Balclutha section.

d) To bring the train at Stirling into the section again, the guard telephones Balclutha who then obtains a tablet from B1 after sending the signal
Release Tablet for Shunting (5-2) to Lovells Flat and obtaining a release. The tablet is then placed in the top slide of B2 and Train arrival (3) sent to the Guard at Stirling.

e) The guard closes up his transmitter S and sends
Release tablet for shunting (5-2) to Balclutha; on obtaining the tablet from S, he unlocks the points and reverses them, moves the train on to the main line, restores to normal and relocks the points, and hands the tablet to the driver (Note that the tablet instrument is left in the unclosed position)

f) When the train arrives at Balclutha or Lovells Flat instrument there, which is then closed up, and
Shunting completed, Tablet replaced (2-5) sent.


Image

Personally, I think these are 'straight' instruments, set up to work as an auxiliary pair; the three-position visual indicator was removed, and a plate reading 'Tablet Transmitter' put in its place.

Also of interest, and something that isn't often recorded in UK installations is the number of tablets per instrument: each Tablet Transmitter had four tablets for each machine with another nine for the operation of the main section up to a total of 36 tablets for the section, normally there were 24 tablets although there were cases where there were 30 tablets per section.

Seems that Tablet Transmitters were a bit more popular in NZ than auxiliaries in the UK - 11 known installations, two of them temporary (Paeroa area during recovery of the old line, Mangaroa during the construction of the Rimutaka Tunnel) and one Smart Road to Lepperton which had two tablet transmitters in the section [if this meant that one end had three instruments in the same box or that there were two instruments at the one end, I don't at this stage know.
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Re: No 7 and Auxiliary Tablet Instruments.

Unread postby Peter R » Thu Feb 8, 2018 2:02 pm

Hi all,

I have recently found some photos of the Muir of Ord auxiliary instruments and their interiors after they had been returned to the main S&T Store in Salkeld Street, Glasgow, before being taken on to NRM York. The No.7s from Lentran and Muir of Ord were also on a pallet alongside.

I'd like to swap these photos for the Tyers info mentioned previously, but not sure how photos can now be shared - I don't have a photo hosting website. If someone can advise I'll gladly share.
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Re: No 7 and Auxiliary Tablet Instruments.

Unread postby Is Line Clear » Thu Feb 8, 2018 5:04 pm

Peter R wrote:Hi all,

I have recently found some photos of the Muir of Ord auxiliary instruments and their interiors after they had been returned to the main S&T Store in Salkeld Street, Glasgow, before being taken on to NRM York. The No.7s from Lentran and Muir of Ord were also on a pallet alongside.

I'd like to swap these photos for the Tyers info mentioned previously, but not sure how photos can now be shared - I don't have a photo hosting website. If someone can advise I'll gladly share.


I think that if you don't have suitable facilities to share, the 'Guvner' (John Hinson) may be able to help. Perhaps.
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Re: No 7 and Auxiliary Tablet Instruments.

Unread postby vic south » Fri Feb 9, 2018 7:38 pm

If I have understood correctly, the 'tablet transmitter' arrangement described by MRFS is the system used on the Midland Railway Trust between Hammersmith signal box and Butterley Ground Frame, where a second pair of No.6 instruments are used for the purpose. A similar arrangement existed between Seymour Jct and Oxcroft Ground frame on the Clowne Branch in North Derbyshire. There was a pair of No.6 instruments between Elmton & Creswell Jct and Seymour Jct and a set of RSco instruments between Seymour Jct and the GF hut at Oxcroft. These instruments were very simple and held only one tablet each - much like the release receptacle on a ground frame but electrically connected to it's opposite number. I 'm pretty sure they survived right up to the end of the branch and long after through traffic had ceased, the final trains into Oxcroft Disposal point all being worked in from the Seymour Jct end.

The MRT did have an auxilliary instrument that looked a lot like a No.6, except that there was no bell plunger, just a solid fronted commutator. I think it came in a job lot of instruments from the Mid Hants Railway. We never did figure out how to use it! :roll: That was over twenty years ago so I've no idea if they still have it.

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Re: No 7 and Auxiliary Tablet Instruments.

Unread postby Corrour » Fri Feb 9, 2018 10:44 pm

I'd love to see the stuff MRFS originally posted but the links seem to no longer work.

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Re: No 7 and Auxiliary Tablet Instruments.

Unread postby Pete2320 » Sat Feb 10, 2018 1:06 pm

Corrour wrote:I'd love to see the stuff MRFS originally posted but the links seem to no longer work.

Robert


I'm having the same problem.

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Re: No 7 and Auxiliary Tablet Instruments.

Unread postby Mike Hodgson » Sat Feb 10, 2018 9:23 pm

Thats because Photobucket decided to stop hosting pictures for free and suddenly and without warning started demanding to be paid for this service they had previously advertised as free.
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Re: No 7 and Auxiliary Tablet Instruments.

Unread postby Corrour » Sun Feb 11, 2018 4:40 pm

Thanks Mike I hadn't realised links were in same category as these annoying 'speedometers' :-(
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Re: No 7 and Auxiliary Tablet Instruments.

Unread postby Pete2320 » Tue Feb 13, 2018 12:32 pm

We have discussed this before, largely in a thread titled "Instrument Colours", started by MRFS!
viewtopic.php?f=2&t=2927&hilit=lentran&start=0

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