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Tablet versus ETS (automatic working)

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Tablet versus ETS (automatic working)

Unread postby stevej » Tue Aug 9, 2016 3:55 am

G'day,
I have been hunting through numerous postings, so I do apologize if this question has been posted previously.
I had been recently told that Tablet system was not capable of automatic working, tablet instruments not operable at unattended stations.
I am wondering if this is correct.
I know that Tablet system was originally utilized here in NSW, but don't know any specifics.
The Tablet system here being replaced by ETS.
Steve.
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Re: Tablet versus ETS (automatic working)

Unread postby Richard Lemon » Tue Aug 9, 2016 7:10 am

Steve,

Depends, I suggest, on the type of instrument.

With most Tyer instruments "Automatic" / "Remote Operator" would not be possible, but Tyer developed an instrument for this purpose. In SRS Signalling Paper No. 11, David Stirling describes this as the Tyer's Absolute Automatic Instrument. It was based on the No. 7. The only known use in the UK was on the Campbeltown and Machrihanish Light Railway.

MRFS may be able to add more!

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Re: Tablet versus ETS (automatic working)

Unread postby MRFS » Tue Aug 9, 2016 10:15 am

Although it never happened No 5 non-permissives tablets *could* have been fitted with remote operators.

29/4/1959: 0826. Last train carrying a tablet left Grasstree for Antiene. Last tablet woerked train in NSW.
ND: Why is there a door handle on the inside of my airing cupboard?
MF: Because it's the fire exit from Narnia.

I like David Lynch films. I don't consider incomprehension to be a barrier to enjoyment.
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Re: Tablet versus ETS (automatic working)

Unread postby stevej » Wed Aug 10, 2016 4:19 am

G'day Richard and MRFS,
Thanks for the responses.
I guess that back when tablet system was mostly being utilized, the need for unattended operation was not generally necessary.
I have seen tablet system referred to naturally in the UK, plus also in New Zealand, Japan, South Africa.
But, I have never actually witnessed the operation in person.
Grasstree NSW would be very different today to that back when tablet was still in use.
I think that I have noticed another posting regarding the use of a key with tablet to permit ground frame operation.
Naturally that key being separate to the actual tablet.
CTC and Train Order (computerized) working do remove the localized tradition from the system.
I much preferred token working systems, ETS and OTS&T.
It would have also been interesting to work with Tablet system.
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Re: Tablet versus ETS (automatic working)

Unread postby baconandeggs » Wed Aug 10, 2016 5:51 am

stevej wrote:G'day Richard and MRFS,

I think that I have noticed another posting regarding the use of a key with tablet to permit ground frame operation.
Naturally that key being separate to the actual tablet.
.
Steve.


Like you I have never seen the tablet system in operation. The last section in NZ (Featherston - Masterton) closed in 1994. It had been in operation since 1902.

Ground frames were unlocked with the tablet. There was also a Bank Engine key which when removed disconnected the circuit. Here are extracts from the NZGR Regulations for Working Single Line Railways By The Electric Train Tablet System.

18. USE OF BANK-ENGINE KEY ON ELECTRIC TRAIN TABLET SECTIONS

(a) Bank-engine Key -To facilitate the working of trains over steep gradients where it is necessary for an engine to assist a train in the rear but not to run the entire length of the tablet section, the engine in the rear must carry a bank-engine key (as described below) as authority to return to the station from which the key was received.
(b) Description of Bank-engine Key -Except when installed for other specific purposes the bank-engine key must be used only for an engine assisting a train in the rear to an authorised metrage and in accordance with these instructions.

At the stations concerned, the tablet instrument is controlled by a bank-engine key which, when turned and withdrawn, disconnects the electric circuit of the tablet instruments so that bell signals cannot be exchanged nor a tablet obtained until the key has been replaced in position. A plate on the key is engraved with: "Bank-engine Key"; the name of the station from which the bank engine starts; and the metrage to which the bank engine is authorised to run before returning.


36. TABLET-LOCKED SIDINGS

(a) Points on the main line giving access to sidings and controlled by a tablet lock cannot be opened without a tablet for that section of the line where the siding is situated being placed in the tablet lock; the tablet cannot be moved from the tablet lock until the points have been placed in the proper position for trains to pass upon the main line, and are securely locked.
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Re: Tablet versus ETS (automatic working)

Unread postby baconandeggs » Wed Aug 10, 2016 6:16 am

stevej wrote:G'day Richard and MRFS,

I think that I have noticed another posting regarding the use of a key with tablet to permit ground frame operation.
Naturally that key being separate to the actual tablet.

It would have also been interesting to work with Tablet system.
Steve.


There was also the so-called 'tablet transmitter". I cannot remember exactly how it worked so the following is a summary from memory.

If train A was running on the main line with a tablet and then entered a branch line the tablet was placed in the "tablet transmitter". This allowed a second tablet to be withdrawn and train B to run on the main line. Train A's tablet became locked in the transmitter. While on the Branch train A probably operated under Open Section (timetable) or One Engine in Steam regulations.
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Re: Tablet versus ETS (automatic working)

Unread postby Richard Lemon » Wed Aug 10, 2016 6:57 am

Note for the Gentlemen above, No. 6 tablet working is still in use in the UK on Network Rail's Stranraer line. Key Token is in widespread use both on Network Rail and Heritage Lines. ETS on the Ffestiniog. But, the list could go on and on - this is just a taster!

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Re: Tablet versus ETS (automatic working)

Unread postby Andrew Waugh » Wed Aug 10, 2016 11:32 am

baconandeggs wrote:There was also the so-called 'tablet transmitter". I cannot remember exactly how it worked so the following is a summary from memory.

If train A was running on the main line with a tablet and then entered a branch line the tablet was placed in the "tablet transmitter". This allowed a second tablet to be withdrawn and train B to run on the main line. Train A's tablet became locked in the transmitter. While on the Branch train A probably operated under Open Section (timetable) or One Engine in Steam regulations.


A tablet transmitter was simply a second pair of instruments of the same gauge as the main instruments, but normally out of phase.

If you image a normal section A-B, with an intermediate junction at C. Assume B is the origin and destination of branch line movements. There is the usual pair of instruments at A and B used for through trains. In addition, there is an additional pair of instruments B-C (the tablet transmitter), of the same gauge as the main instruments but normally out of phase. One tablet is secured in the tablet transmitter instrument at B. The junction points at C are secured by a tablet lock.

A movement from B to the branch line is as follows. The signalman at B gets a tablet from the through instrument and gives it to the train. This trundles down the main to the junction. The tablet is used to unlock the junction, the train enters the branch, and the junction points are restored and the tablet retrieved. The tablet is then inserted into the tablet transmitter instrument at C, bringing the instruments B-C back into phase. This allows the tablet in the tablet transmitter instrument at B to be removed. This tablet is then put in the main instrument at B, restoring it to normal and allowing further main line movements. The tablet is essentially 'transmitted' from C back to B.

Movements from the branch are the reverse. A long section tablet is obtained at B and inserted in the tablet transmitter instrument, normalising it. The tablet in the instrument at the junction C can then be obtained, allowing the junction to be unlocked and the branch line train to return to B. The tablet is then inserted into the main line instrument, freeing it.

Tablet transmitters could be (and were) implemented with staff instruments as well (and probably token instruments). However, with staff instruments, an intermediate instrument served the same purpose and was cheaper.

The main risk of all of these was that the branch line train would restore the tablet in the transmitter tablet at the junction before clearing the main line. This certainly happened in NZ (with tablet transmitters) and in Victoria (with intermediate electric staff instruments). Another obvious problem was Signalman Thoughtless at B getting the tablet from the returning branch line train, and putting it in the tablet transmitter, locking everything up until someone travelled to the junction to work the instrument.
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Re: Tablet versus ETS (automatic working)

Unread postby Andrew Waugh » Wed Aug 10, 2016 11:54 am

I think it was Charles Gavan Duffy (*) who commented that the "tablet was an instrument, where the staff instrument was a machine". By which he meant that tablet instruments were delicate and needed gentle handling lest they jam, whereas staff instruments were robust. These were Nos 2, 3, & 4 instruments, not the more recent 6 (UK) and 7 (NZ) instruments. Another Gavan Duffy description was of being allowed behind the scenes at Goulburn coming home from boarding school on the Melbourne Express and watching the "stately" process of obtaining the tablet. Everything had to be done slowly, gently, and in the right order. As a schoolboy he wasn't allowed to work the instruments lest they jam and delay the Express.

(*) Gavan Duffy was a very early signalling enthusiast in Victoria, active from the late 1880s through to the 1950s. The Chairman of Commissioners (equivalent to the UK General Manager) once described him as the "most unauthorised person in Victoria" (a play on the notice on the door of every signal box - no unauthorised persons allowed). He was once asked how he got into so many signal boxes. He replied "I always have the key - a bottle of beer". When asked if this always worked, he replied "Sometimes it takes two bottles."
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Re: Tablet versus ETS (automatic working)

Unread postby Chris Osment » Wed Aug 10, 2016 12:17 pm

Richard Lemon wrote:Note for the Gentlemen above, No. 6 tablet working is still in use in the UK on Network Rail's Stranraer line......


...and on heritage railways on the Corfe Castle - Swanage 'long' section, as well as some other lines I believe. Coming one day to the Lynton&Barnstaple too :-)

There is one instrument only now in use at Midsomer Norton (South), at the moment issuing a single tablet as a surrogate OES staff.
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Re: Tablet versus ETS (automatic working)

Unread postby JRB » Wed Aug 10, 2016 8:05 pm

The "tablet transmitter" seems more like an ordinary intermediate instrument with a different name, not a pair of instruments or other complication.
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Re: Tablet versus ETS (automatic working)

Unread postby stevej » Thu Aug 11, 2016 5:57 am

G'day all,
Crikey, a fair bit of info to digest here.
I have saved the thread to my usb stick to peruse in depth at home.
Thanks for all the info.
Steve.
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Re: Tablet versus ETS (automatic working)

Unread postby Andrew Waugh » Thu Aug 11, 2016 1:14 pm

JRB wrote:The "tablet transmitter" seems more like an ordinary intermediate instrument with a different name, not a pair of instruments or other complication.


Yes, I agree it seems like an ordinary intermediate instrument, but I assure you it involved an additional pair of instruments in addition to the main pair of instruments.

The NZ installations are described in 'Semaphore to CTC', section 8.8. This book is probably not common in the UK, but I know MRFS has a copy. (And in fact he's already posted the germane details in another thread http://forum.signalbox.org/viewtopic.php?f=2&t=2953)

A similar arrangement in Victoria has also been discussed in another thread. See http://forum.signalbox.org/viewtopic.php?f=7&t=3172
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Re: Tablet versus ETS (automatic working)

Unread postby Alan Norris » Sun Aug 14, 2016 2:53 pm

Andrew Waugh wrote:I think it was Charles Gavan Duffy (*) who commented that the "tablet was an instrument, where the staff instrument was a machine". By which he meant that tablet instruments were delicate and needed gentle handling lest they jam, whereas staff instruments were robust. These were Nos 2, 3, & 4 instruments, not the more recent 6 (UK) and 7 (NZ) instruments. Another Gavan Duffy description was of being allowed behind the scenes at Goulburn coming home from boarding school on the Melbourne Express and watching the "stately" process of obtaining the tablet. Everything had to be done slowly, gently, and in the right order. As a schoolboy he wasn't allowed to work the instruments lest they jam and delay the Express.

(*) Gavan Duffy was a very early signalling enthusiast in Victoria, active from the late 1880s through to the 1950s. The Chairman of Commissioners (equivalent to the UK General Manager) once described him as the "most unauthorised person in Victoria" (a play on the notice on the door of every signal box - no unauthorised persons allowed). He was once asked how he got into so many signal boxes. He replied "I always have the key - a bottle of beer". When asked if this always worked, he replied "Sometimes it takes two bottles."


I've seen No 7 in the UK as late as the 1970's - my recollection is that they were used on the Oban line (along with No 6). There were also a pair of No 1 used across the Forth Bridge.
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Re: Tablet versus ETS (automatic working)

Unread postby Chris Osment » Sun Aug 14, 2016 6:14 pm

I've seen No 7 in the UK as late as the 1970's - my recollection is that they were used on the Oban line (along with No 6). There were also a pair of No 1 used across the Forth Bridge.

Were those not "No 1 Improved" models - ie No 1 base + No 6 top?
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