Railway signalling discussion

Dowlow branch

Current and future British signalling (UK except Northern Ireland)

Re: Dowlow branch

Unread postby Simon Foster » Fri May 14, 2010 10:14 pm

kestreleyes wrote:indeed,the machine at great rocks is the two position one, the hindlow one being the 3 position, i cant actually remember there being a machine at higher buxton,but the old parcels dmus used to lock themselves in there all day long so there must have been something arranged so to speak for getting key into nearest machine

I've found a set of drawings for this section from years ago, including a signalling plan. The GF at Higher Buxton states that trains may not shut inside, so if there ever was such facility it must have been in the early days of the single line. The plan is undated (I copied this around 1985), but does bear a note from 1984 regarding the temporary replacement of EKT with OTW using a single token as a staff. I think this was to allow the instruments to be borrowed for use elsewhere, possibly New Mills South - Northenden, after someone set light to Cheadle Junction box.

As to the circuitry at Briggs, this consists of a 10 second slow release relay, energised from a Biased Polar MI relay which is connected to the separate 'remote release' lines. Contacts of a repeat relay of this slow release are wired in place of the instrument plunger contacts, which are strapped out. This results in a voltage being put to line, as if a signalman at Briggs had depressed the plunger, for 10 seconds after the 'remote release' plunger at Buxton is released, sufficient for the signalman there to withdraw a token. There is no mention of this being a 'knee' plunger, in fact I think this was just an ordinary open release plunger in a box when I saw it, so the 'knee' arrangement could be a later innovation.

The other circuitry at Briggs is connected in series with the Bell relay (though the bell itself is not wired), and consists of a pair of Biased Polar MI relay coils in parallel, such that one responds to In Phase current and one to Out Of Phase. Contacts of both these relays are included in the same repeat relay circuit as the 10 second timer, and will result in a short pulse (approx 0.5 second) being sent back down the token line. I reckon this is to do with the indicator operation.

I don't know if these indicators were used on other regions or if they were a peculiarity of the LMR. The instruments are described as type 12A. It's been a long time since I worked out the sequence, so treat the following with a degree of caution, and I'd be grateful for any corrections if I have got it wrong.

These depend on a combination of bell and lock path current, and from memory need a bell plunge after a token has been withdrawn to trip the needle at the 'accepting' end (the one at the 'released' end should go over from the Out Of Phase current as the comm is turned back to the belling position after the token has been taken out, if the accepting signalman keeps the plunger down long enough). I have a vague memory of seeing a single beat being returned in this way, to act as confirmation that a token has been successfully removed and also to match up the indicator positions. I can't see this requirement in the current KT Regs though. Of course if this is not sent then sending TES will do it, but until then the indicators will be out of step.

So it looks as though the circuit at Briggs is intended to mimic the actions of the 'missing' signalman. When a release is sent from Buxton to Briggs, and the token is extracted by the traincrew, the indicator there will be tripped by the Out Of Phase line current passed to the bell relay path as the comm completes its rotation. This will also trigger the short pulse circuit when the incoming line current is removed (Buxton signalman releases instrument plunger), sending back a half-second pulse to trip the Buxton indicator.

Going the other way (Buxton giving himself a release via the separate line wires), the Buxton indicator will be operated by the line current, but that at Briggs will not move unless the Buxton signalman plunges (on the instrument itself) after taking the token out. Maybe Dom knows if this is done? It could be that it isn't thought necessary as there isn't normally anyone at the Briggs end to see it anyway.

When a train leaves the section, either arriving at Buxton or shutting inside at Brigss, and the instruments are back in phase, the Buxton signalman will need to 'bell' to Briggs to get a pulse back to send the indicator to 'Normal'.

Quite a clever arrangement, and not one I've come across anywhere else.
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Re: Dowlow branch

Unread postby Noisynoel » Thu Jun 1, 2017 3:19 am

Gents, I am currently building a simsig of the Buxton area and am after a signalling diagram of Briggs Sidings or alternatively a diagram or list of the levers on the GF, just to finalise how it all works. Can anyone help?
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Re: Dowlow branch

Unread postby DaveHarries » Sat Jun 10, 2017 11:17 am

Noisynoel wrote:Gents, I am currently building a simsig of the Buxton area and am after a signalling diagram of Briggs Sidings or alternatively a diagram or list of the levers on the GF, just to finalise how it all works. Can anyone help?

I look forward to seeing that one Noel.

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Re: Dowlow branch

Unread postby Danny252 » Sat Jun 10, 2017 8:15 pm

It appears that it was two levers, presumably one point lever and one FPL, per the following photos:

However, it's since moved to the other side of the track, and the levers are well hidden behind a structure in most photos of the area, so maybe someone will still have to fish out a diagram!

(There is an incredibly low quality video which features it in the background, but I couldn't distinguish between 2, 3, or more levers:
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Re: Dowlow branch

Unread postby kestreleyes » Tue Jun 27, 2017 9:30 pm

Briggs, lever one operates both a derailer in the line going to dowlow and also unlocks the frame,a tyers token lock is attached to this lever too to unlock it

Lever two operates the points under the bridge and the inside end leading to the loading hoppers

The stop board is both low and a few metres back from the derailer as it kept getting hit,,I'm told the quarry is altering a lot of the layout at the dowlow end ,due to problems with derailments and operations, there is a plan in buxton box of the quarry's bit of line,if I get a chance il copy it up for you.
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