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intermediate Miniature Staff instrument

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intermediate Miniature Staff instrument

Unread postby thelineman » Mon Feb 28, 2011 9:44 pm

I found and old circuit diagram which explained how to connect an "intermediate Staff instrument for subsidiary sidings". The diagram sugests a two needle galvanometer, compound coil and other strange stuff. I never saw one of them here in Argentina. I was wondering if they were used in England or Ireland and if there is any photograph.
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Re: intermediate Miniature Staff instrument

Unread postby MRFS » Mon Feb 28, 2011 11:54 pm

Yes they were. I'm 300 miles away from my photos unfortunately. I've also used a couple.

Any chance of seeing the circuit diagram?
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Re: intermediate Miniature Staff instrument

Unread postby thelineman » Tue Mar 1, 2011 12:35 am

Yes I can scan them tomorrow and post them, there are 3 diagrams
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Re: intermediate Miniature Staff instrument

Unread postby MRFS » Tue Mar 1, 2011 1:37 am

Lovely - here's a LINK to an imtermediate instrument - 'M' pattern (and F configuration, rare in GB though favoured in Chile, I gather), and an alteration from a terminal instrument, so the second galvanometer is a later addition, likewise the 'E' configuration at Rhiw Goch LINK - I've found a picture of the intermediate staff hut at Narrabri, but not of the instrument itself, unfortunately.


I've found reference to varied Australian installations, but no photographs. I have seen a picture of a twin-needle single galvanometer, but unfortunately, despite much google-fu no joy, sorry. I suspect that it's in my clutch of RSCo catalogues, miles away.

EDIT: Bingo! Qld!: LINK
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Re: intermediate Miniature Staff instrument

Unread postby thelineman » Tue Mar 1, 2011 3:11 am

So now the question is what´s the second needle for? In the Railway rulebook (Argentina) the system is slightly explained. There is an article that mentions the existance of the instrument but no drawing. It only explains that both the instrument in the station and the one in the siding hut, are usually out of phase.
Tomorrow I´ll scan those things.
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Re: intermediate Miniature Staff instrument

Unread postby MRFS » Tue Mar 1, 2011 11:57 am

Sounds like the rule book is describing an auxiliary pair, used when you need to deliver a staff to a train that is some distance from the signalbox. It saves the Signalman walking to the train - once the staff has been abstracted from the main instruments it is then put in the signalbox end of the auxiliary pair, putting that pair into phase and allowing a staff to be abstracted at the hut.

With an intermediate instrument - consider the locations Belmont - [John Darling Colliery] - Redhead. (The names are unimportant[1]).

The main staff section is Belmont - Redhead. If a train needs to leave John Darling Colliery where there is an intermediate instrument then it will need a release from both Belmont and Redhead for the compound lock in the intermediate instrument - simply speaking one galvanometer will show the release from Redhead and the other needle will show the release from the other end at Redhead.

Slight diversion into other examples, that may help:

[1] Other examples could be Quipolly - [Werris Creek Colliery Junction] - Werris Creek South and Werris Creek South - [Gap] - Bakana. Now the comment about names being unimportant is perhaps slightly incorrect - and ties in with your comment about 'both the instrument in the station and the siding hut are usually out of phase' - *if* you are not talking about an auxiliary pair, the working instructions for the three examples I've given all have one signalbox in charge of the intermediate (the UK convention is that both ends of the section have equal authority over the intermediate and must cooperate).

Both [Gap] and [Werris Creek Colliery Junction] have Werris Creek South recorded as the controlling signalbox; the Belmont branch example [2] has fuller instructions insofar as there is one telephone at the intermediate instrument from John Darling to Redhead - in this case the person operating the staff instrument at John Darling would telephone Redhead for a release, and Redhead would contact Belmont. One galvo would flick first, then when Belmont gave a release then other galvo would flick releasing the lock in the instrument. I'm pretty sure that the staff has to be raised or slightly engaged first to connect the intermediate instrument to line - but you would be able to see that from the circuit diagram.

[2] The Belmont branch is truly fascinating. 'with train' switching from Electric Train Staff to Ordinary train staff at two intermediate crossing loops, and various permutations of banking engines depending on which and how the intervening signalboxes were switched in. Best for another thread, though.
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Re: intermediate Miniature Staff instrument

Unread postby Andrew Waugh » Tue Mar 1, 2011 12:01 pm

The two galvos at an intermediate instrument showed that both signalmen at the ends of the sections were sending current and that the currents through the coils were of the same polarity - hence a staff could be released.

When a staff was lifted into the lock in an intermediate instrument, the through line wires were broken. The current from one end of the section (call it A) was directed through one galvo and one set of lock coils. The current from the other was sent through the commutator, the other galvo, and the other lock coil. If the two currents were the same polarity at the lock coils, the lock would lift and the staff would be released. Removal of the staff would reverse the commutator at the intermediate instrument. As the line current between the ends of the section went through the intermediate commutator, this would give an odd number of reversals through the three commutators and prevent a further staff from being withdrawn at any instruments. Restoring the staff to any of the instruments would give an even number of reversals and allow a staff to be withdrawn.

If you like, electrically, the intermediate instrument was similar to a large electric staff with local and line coils. In this case the line coils were energised normally (through the commutator from the B end of the section). However, the local coil was energised from the A end of the section).
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Re: intermediate Miniature Staff instrument

Unread postby Danny252 » Tue Mar 1, 2011 1:23 pm

MRFS wrote:simply speaking one galvanometer will show the release from Redhead and the other needle will show the release from the other end at Redhead.


One of those "Redhead"s should be "Belmont", no?
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Re: intermediate Miniature Staff instrument

Unread postby MRFS » Tue Mar 1, 2011 4:50 pm

Danny252 wrote:
MRFS wrote:simply speaking one galvanometer will show the release from Redhead and the other needle will show the release from the other end at Redhead.


One of those "Redhead"s should be "Belmont", no?


Yes, sorry about that - was slightly distracted as buying a house at the same time as typing up. Need an extension to the library.......
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Re: intermediate Miniature Staff instrument

Unread postby Chris Osment » Tue Mar 1, 2011 7:02 pm

Was it common in the UK to paint the whole of the instrument according to the configuration colour? And did that practice extend to the 'large' ETS as well as the METS?
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Re: intermediate Miniature Staff instrument

Unread postby MRFS » Wed Mar 2, 2011 1:47 pm

Chris Osment wrote:Was it common in the UK to paint the whole of the instrument according to the configuration colour? And did that practice extend to the 'large' ETS as well as the METS?


I've started a new topic HERE on instrument colours.
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Re: intermediate Miniature Staff instrument

Unread postby Pete2320 » Wed Mar 2, 2011 3:42 pm

MFRS wrote
Need an extension to the library.......


....and an IMR :wink:

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Re: intermediate Miniature Staff instrument

Unread postby MRFS » Wed Mar 2, 2011 5:17 pm

Pete2320 wrote:MFRS wrote
Need an extension to the library.......


....and an IMR :wink:

Pete


Although off-topic that is factored in - there's a nice space that could take a 'V' frame......
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Re: intermediate Miniature Staff instrument

Unread postby thelineman » Wed Mar 2, 2011 6:57 pm

The diagrams:

http://i856.photobucket.com/albums/ab128/nicolas799/2.jpg
http://i856.photobucket.com/albums/ab128/nicolas799/1.jpg

The only diagrams I have. One of them shows the two neddle galvanometer.
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Re: intermediate Miniature Staff instrument

Unread postby thelineman » Wed Mar 2, 2011 7:07 pm

MRFS wrote:in this case the person operating the staff instrument at John Darling would telephone Redhead for a release, and Redhead would contact Belmont. One galvo would flick first, then when Belmont gave a release then other galvo would flick releasing the lock in the instrument. [/size]


I you look at the digrams, the telephone has to be connected, but there is not block bell connected to the intermediate instrument.
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