Victorian Block Instruments.

[Michael Hodgson]

Haven't followed all of that to the circuits but it certainly sounds promising. 

 

The idea that the lock coil might be a later afterthought is certainly plausible, as 2-position block tended to be used in the early days before block working became mandatory, but upgrading to 3-wire was expensive, yet misunderstandings over the difference between Line Closed  and Train in Section were enough of a risk to cause one or two accidents.   Walker died in 1882, before Block working even became compulsory and your instrument is clearly an improved version over his first ideas in 1855, so it's not unreasonable to expect further enhancements by his successors

https://collection.sciencemuseumgroup.org.uk/objects/co410161/telegraph-block-instrument-early-walkers-type-telegraph-instrument

 

I am pretty sure I read somewhere of a SR change in the signalman's instructions on one particular 2-position block instrument type following grouping, though I don't think it's relevant here as it probably wasn't the Walkers.  One Division of the SR had been doing things differently from another Division using the same 1-wire instruments - possibly the Tyers?  I think one of the pre-group companies had originally instructed that their miniature semaphores be in the off position (on the grounds that the line was clear of traffic) when a 3-position instrument would have been in the Normal Position.  This is probably related to the preamble in various block regulation booklets to say that the normal position of signals is at Danger/Caution and the normal position of Block instruments is at Line Blocked/Line Closed given that it wasn't always uniformly so.

[RailWest]

10 hours ago, Michael Hodgson said:

 

 

I am pretty sure I read somewhere of a SR change in the signalman's instructions on one particular 2-position block instrument type following grouping, though I don't think it's relevant here as it probably wasn't the Walkers.  One Division of the SR had been doing things differently from another Division using the same 1-wire instruments - possibly the Tyers?  I think one of the pre-group companies had originally instructed that their miniature semaphores be in the off position (on the grounds that the line was clear of traffic) when a 3-position instrument would have been in the Normal Position. 

That sounds like the situation with Sykes Lock & Block, where IIRC the L&SWR worked it differnetly from the other SR constituents...

[Michael Hodgson]

2 hours ago, RailWest said:

That sounds like the situation with Sykes Lock & Block, where IIRC the L&SWR worked it differnetly from the other SR constituents...

Yes, it was probably that I was thinking of - so definitely irrelevant to the Walkers.

[RailWest]

I have noted also in Stirling's book for the NRM a photo of a Walker instrument attributed to Mangapps Farm Museum. If they have (at least) one then maybe they will have a circuit diagram as well - it could be worth asking them just in case.

[Harlequin]

Hey! An amazing bit of serendipity! eBay just showed me this item because I'd looked at some rotten signal box diagrams for sale:

 

https://www.ebay.co.uk/itm/334116994638?campaign-id=90001&run-date=20210818023000&templateId=0bff632b-c44d-4b26-aa5d-5d92d3981176&templateVersion=606&co=14601&placement-type=mfe.piyi2v2P&user-id=43027362057&instance=1629279000&site-id=3&trackingCode=TE76002_T_ALL&placement-type-name=mfe.piyi2v2P&mfe-Id=101311&mkevt=1&mkpid=2&emsid=0&mkcid=8&bu=43027362057&osub=656564c7c3819faff7e14bc1fc5c6ef3%7ETE76002_T_ALL&segname=TE76002_T_ALL&crd=20210818023000&ch=osgood&sojTags=osub%3Dosub%2Csegname%3Dsegname%2Ccrd%3Dcrd%2Cch%3Dch%2Cchnl%3Dmkcid

 

Any use?

 

[RailWest]

If you look careful, then although the battery is connected across the commutator, there seems to be NO centre-tap connection from the battery to earth. So the commutator therefore must somehow 'swop' polarity between two outputs, with the circuit going from A down the Line to B then back thru' Earth to A and then back thru the commutator. 

 

Also, the white and red indicator coils seem to be worked in parallel, rather than series :-)

[neale126]

Phil,  those are just what I wanted.  Thank you.

 

I also have the matching connector leads that mate with the modified wiring etc., so with a bit of luck I can see how they were going to be used in the modified state.

 

Chris, I agree so will be recehecking everything just to make sure before powering up.  In the first instance I will be using current limited bench power supplies and starting with maybe 6 volts.  I would imagine that the line resistance would be the main reason for having higher voltages.  The diagram show 7 cells which is nearer 14 volts.

 

Neale.

 

 

[bécasse]

42 minutes ago, neale126 said:

In the first instance I will be using current limited bench power supplies and starting with maybe 6 volts.  I would imagine that the line resistance would be the main reason for having higher voltages.  The diagram show 7 cells which is nearer 14 volts.

 

 

Wet Leclanche cells, which is what would have been used originally, produce 1,4 volts, so seven in series would have produced 9,8 volts. Traditional dry cells produce around 1,5 volts when fully charged, although the various alkaline ones tend to be marginally lower, but the resultant 10,5 volts shouldn't create any problems. I wouldn't go above 10 volts using a bench supply as the insulation in various "antique" parts probably isn't in brilliant condition. 6 volts should be fine.

[neale126]

I stand corrected.  I thought they might have been lead acid but historically that has to be wrong.

[Michael Hodgson]

20 hours ago, RailWest said:

I have noted also in Stirling's book for the NRM a photo of a Walker instrument attributed to Mangapps Farm Museum. If they have (at least) one then maybe they will have a circuit diagram as well - it could be worth asking them just in case.

They have examples of most of the surviving types of block instrument, mostly in display cases - the place is well worth a visit, but whether they've got the circuitry I don't know.

 

Harlequin has found the answer though, and as suspected the diode and resistor don't belong there.  Perhaps added if they were running off a higher voltage than necessary.

[5BarVT]

1 hour ago, Michael Hodgson said:

Harlequin has found the answer though, and as suspected the diode and resistor don't belong there.  Perhaps added if they were running off a higher voltage than necessary.

Possibly a.c. and half wave rectified?

Paul.

[neale126]

Firstly, thanks for all your help and information.

 

The sets I have were probably a later iteration where a electro-mechanical commutator lock was added but all the diagrams and sketches I have accrued to date are for the previous version without the lock function.

 

I have now fathomed out what the wiring modifications were and the reasoning behind them. The idea was, apparently, to make them work for single line operation and to run them from a split supply.  The extra resistor and diode provide protection so the lock solenoid only operated with a +ve voltage and the resistor gave current protection.  The modified sets were to use 2 wire and return between signal boxes.

 

For the moment I have put the units to one side until I can get more connectors to complete the inter unit wiring.

 

Neale.

[neale126]

Finally managed to get the Walkers instruments working and talking to each other.

 

As I mentioned previously they had been modified for 2 wire plus return operation and also for use split supplies.

 

They proved to be fiddly to operate and get unambiguous operation and the order sequence in which everything was actioned had to be right.

 

It quickly became very clear that they were not suitable for use on the actual railway so they have now been consigned to the railway museum.

 

Many thanks for all who provided information and advice.

 

Regards,

 

Neale.