Victorian Block Instruments.

[neale126]

I have a couple of Victorian Block instrument sets which I was hoping to install between the two signal boxes on a private 2' gauge railway to supplement the telephone system currently used.

 

I have identified the boxes as a Walkers 1 wire 2 position Block Instrument with top mounted bell and a Walkers 1 wire Block Instrument Control Box incorporating bell key and disc indicator.

 

Not model railways but I would be grateful for any information/references concerning operation or technical details about them. Each instrument consists two parts; the indicator/bell unit and the control unit. There are three wires between the indicator/bell and the control boxes and then three wires from the control box to the outside world.

 

My problem is that I cannot find any additional information these such as how they were operated and connected into a system. They are well made, if slightly over the top compared to later units, and appear to be in working order. I guess they were manufactured in the late 1800's.

Can anyone can provide information or links please?

Thank you.

Neale.

[RailWest]

Are the internal terminals labelled in any way? eg possibly 'C', 'Z', 'E', 'L' ?

 

[RailWest]

Attached is a copy of the relevant instructions from the BR(S) Supplement to the 1960 Block Regulations (the 'apple green' book). 

 

I have not yet found an actual wiring diagram - hopefully someone else on here may have one - but as they were 1-wire 2-position instruments then the basics should be quite straightforward. I suspect that most connections would have been to/from the control instrument and that the main instrument was simply inserted into the Line Wire circuit.

 

Can you perhaps also provide some interior photos of the wiring and terminals for external connection?

Edited August 14, 2021 by RailWest

[The Stationmaster]

Good to see that I'm not the only person with a copy of the un-numbered Southern Region supplement to the 1960 Block Regulations and alas that is the only information I have on these instruments although presumably they used an earth return circuit.

[RailWest]

I did look also in David Stirling's Volume 2 on Block Working for the Friends of the NRM, but although Walker's get a mention there is no more specific detail therein :-(

[Michael Hodgson]

Suggest you ask this question on https://signalbox.org/the-blower/

here you will probably find more people with the relevant technical knowledge.

The regulations/supplement tell you how to use it, not how it works. 

 

1-wire implies an earth return as does 3-wire. 

That's not say there would never be an extra line wire if the earth return was not very good.

 

3- wire is simpler in that one wire does the block indications for the Up line, another for the Down (using a continuous current of one polarity for Line Clear and opposite polarity for Train on Line) and the third is for the bells.

1-wire requires more complex circuitry and relies on a pulse of appropriate polarity every time an indication change is required, whereas the 3-wire block  indicators fail to Line Closed if the wire breaks.  1-wire is more economic as it reduces the cost of the pole route, but at the expense of a more complex design of instrument.  The 3-wire instruments are usually easier to operate too and less intolerant of fast operation. 

 

Railwest's question is valid - many instruments are stamped to show where to connect them

C (carbon) and Z(Zinc)  - battery connections (-ve and +ve)

L is Line wire and E is the Earth return. 

 

You would need two control boxes and two indicator/bells to wire it up prototypically, one for each end of the section.  If you have just the one, the circuit to demonstrate would have to be different. 

[neale126]

Firstly thanks to all for their replies.

 

Chris.

There is no internal marking on the connections unfortunately.  That would be too easy.

Someone has already added connectors to both units, three pins on the Block Indicator/Bell and 6 pin connector on the Control Box.  I think that probably 3 wires from the Block Indicator go to three pins on the Control Box with the remaining three pins from that to the outside world.  I have assumed (hopefully correctly) that those three wires are the signal line, +V supply and earth.

The information from the BR(S) Supplement is useful so thank you.

I will post pictures from inside the boxes and I am also going to sketch out the circuit so I can attempt to follow the sequences.  This I will also post.

 

Michael,

I will post on 'The Signal Box'.  Thanks for the suggestion.

There are two sets of boxes so I have enough for both ends of a block.

 

I am reluctant to place any power on the units until I have some idea what the original design voltage was.  later instruments probably used 12 volt but due to the age of these it may be lower.

Neale.

[RailWest]

I would test with about 6V to start. It might not be enough to ring the bell, but should work the indicators without ruining them :-)

 

Photos + circuit diagrams of the interior should be sufficient to work out the basics.

 

You ought to need only 2 wires between the two instruments, one for Line and one for Earth (return).

 

Power supplies can vary, as some instruments simply have C + Z and the commutator is double-pole and reverses the polarity as necessary, whereas others have C + a centre-tap (to give a 0v) + V (basically two power supplies in series) and the commutator is just a SPDT.

Edited August 14, 2021 by RailWest

[Michael Hodgson]

I don't know the Walker instruments.  Glad to hear you've got two sets - that means you can wire as per prototype if somebody comes up with the circuit.

 

Voltage for block instrument circuits tends to be specified as V+ which is less than helpful.  The problem is that the voltage required to drive it in service has to be enough to overcome losses due to resistance of the line wire, which varies according to the length of the section, the wire used and even the weather.  So S&T use as many cells as it needs to get satisfactory operation.  However I take it you won't be putting the control box 5 miles from the miniature semaphores! 

 

Railwest mentioned the split power supply and commented that there would only be the line wire and earth return running between the two boxes.   In the real world there would be one of these supplies at each end of the section.  For your setup, you may be wanting to run both sets off a single supply - this could possibly be the explanation of the third wire on the connectors you have found. 

[LNERGE]

Circuit diagrams will exist for these instruments and if you are still stuck for them I can have a look. What will be harder is to find the relays to go with them to bring controls outside of the instrument to enforce line clear control etc. It took me ages to source the stick over relays for my Tyers GE one wire instruments

[neale126]

I have drawn out the circuits and added pictures of the internals.  The relays and solenoids do all seem to work when individually powered with a low voltage.  In the Control Box I am not sure whether the Diode D1 or the Resistor R1 are original fit and have been added when the additional wiring was carried out.

In the Bell and Block Indicator box the white signal indicator is released (drops) when the upper solenoids are activated.  A pin holds the signal until the solenoid is driven.

 

Similarly the Bell Solenoid has to be activated to release the red signal and a pin on the actuating arm also holds this in position.

 

What I don't know is exactly how these two boxes are connected together and to the outside world. 

 

Neale.

 

Edited August 15, 2021 by neale126
Picture change

[RailWest]

I would expect to find at least one normally-closed (NC) contact with the bell-push, as that is usually cut into the line wire.  In your first photo there is an unlabelled terminal which curves over the top of the push moving contact, just above the white 'choc block' . I suspect that is a NC which does not seem to appear in your drawing?

 

As the commutation appears to be a simple SPDT switch (but is it biased to be centre-off?) then I would suspect that the instruments use a +Ve + Ov centre-tap + -Ve power supply arrangement 

[neale126]

Chris,

 

The contacts are both NO and close when the button is pushed.

 

The commutation is not mechanically biased and cannot be turned to Clear ubless the Lock Coil L1 is activated.

 

Neale.

[RailWest]

In which case, then what is the terminal ringed orange in my image connected to ? Is that not a NC contact on the moving part of the plunger 'arm' ?

[RailWest]

...and in this image the terminal block ringed in yellow is attached to the (modern) blue wire, but to what is the wire just visible on the lower screw attached?

[neale126]

Chris,

 

You are correct in that the terminal ringed in orange is a back contact (N.C.) that connects to SW1 pin 3 in the diagram which in turn goes to the white wire and the diode.  As nothing was actually connected to it I missed that.

 

The wire in the second image, circled in orange, is the link via the back panel to SW2 pin 3 on the commutator.  It is buried in a slot and filled in and is original.

 

The main problem I have is that the person who added the modern wiring, extra components and connectors did this several years ago and died soon after.  Unfortunately nothing was documented.

 

This is why I am hoping that someone may either have circuit diagrams or a system interconnection diagram.

 

Many thanks.

 

Neale.

[RailWest]

A further question then..:-)

 

Looking straight on, the 'spring' arm from S3 /appears/ to be a 'T' shape and goes to both 'contact1' and 'contact 2'. However seen side on then another 'spring/ arm from S4 is visible. 

 

I can't tell from the photos whether the two spring arms are completely isolated or whether, when the plunger is pressed, they connect to each other as well. Does the NC contact only connect with the S3 and not the S4 arm as well? Is the S3 arm actually a 'T' shape, or are the two arms each an upside-down 'L' shape - if you see what I mean?

[Nick C]

Might any of the diagrams in this PDF be of any use? Page 99 onwards.

 

Source: https://dickthesignals.co.uk/home/heritage-signalling-information/index.html

 

Edit: The LNER document on the same site has several diagrams for Tyer's 1-wire 2-position instruments - I don't know how similar the two makes were in terns of the wiring...

Edited August 16, 2021 by Nick C
added more info

[neale126]

Chris,

 

The spring arms are isolated and, apart from the missing NC contact, are as the diagram.  The block behind the striker on the top spring arm is an insulator.

I'm not much of photographer but have included another couple of photos.

 

Nick, thanks for the links.  Unfortunately all the instrumentation in the PDF seem to be the later 3 wire type.  The LNER document is interesting but uses a galvanometer indicator and requires tokens.

 

Neale.

[LNERGE]

SWD16 is worth a look. SWD14b too. 

[RailWest]

Ah...now I /think/ I get it :-)

 

The horizontal cross-piece at the top is completely separate from the two vertical springs? When the plunger is pressed than the contacts at top LH and top RH are connected, also the NC contact on the front is broken ant the two vertical springs are connected.

 

As I mentioned previously, I would have expected the NC contact to be in the circuit from the commutator 'common' via the plunger to the Line wire, but clearly not. Also it is clear from the instructions that pressing the plunger change the white arm at the plunging end and the red arm at the remote end, would normally would require the two set of coils to be in series in the line wire circuit, whereas the circuit for the indicators suggest that they might be in parallel.

 

Judging from the lower image above, at one time that seems to have been a contact behind the plunger 'cross bar', so some sort of modification in the past?

[Michael Hodgson]

As you have pointed out, the resistor does not look original, and like all the coloured wires is a modern addition or replacement. 

 

It is likely that the internal circuit differs from the original, as I don't believe the original circuit would have included a diode.  The thermionic diode (as in radio valves) dates to 1904, the semiconductor diode principle was known about earlier but not in general use until much more recently.  Why is it there?  To suppress back EMF from the bell or a relay coil?  The circuit to the power supplies may also be different from original - the original would have had a power supply at each end, but a demo circuit within one building might share a single power supply - the diode might have been a consequence  of that.

 

I would expect the bell at the far end only to operate, that's where Railwest's additional normally closed contact come in.  I would expect it to work regardless of the position of the commutator, but  it does not appear that the circuit ran through the bell/red signal release coils when the commutator was in the clear position if the cable colours of the connecting cable were the same as the internal wires, as one might logically have expected?   

 

Railwest suggests it was a simple two-position commutator, but I think not.  It appears that the trigger which releases the block disc from Train in Section to Blocked drops the commutator to a mid position?   So either Line Blocked or Train in Section might be an open circuit position?  Some of the working can be deduced from the instructions to the signalman.  With 1-wire instruments the sequence of moving the commutator and ringing/acknowledging signals is important, whereas on a standard BR bakelite block it doesn't really matter whether you turn the commutator immediately before, immediately after or while you are acknowledging the Is Line Clear? signal

 

The commutator at A has to work the Disc Indicator to Line Clear (mechanically - rotates with it?) and with the commutator in that position, B's first plunge as part of the acknowledgment of the ILC? codes causes his own white release at B and the Red Arm at A to lower.  Both these arms represent authority to lower A's starter (it's white at B because viewed from B, you can only see the back of the signal)  

 

When A sends TES, B moves his commutator again which puts the arms back on again (A should be putting his starter back to Danger behind the train) but the disc shows Train in Section.

 

Once the train is clear of the section B works the trigger to release the disc to Blocked (mechanical, sprung-operated?) and sends Train out of Section.

 

It's a sort of 2 1/2 position block, in that it is only two-position at A (the red arm) but 3-position at B (the disc).  The white arm just repeats what the red arm at the far end is doing. 

 

 

[neale126]

OK I have attached a corrected circuit diagram with the back contact on the Bell Push.  Also the wire colour positions have been moved as they are not original and at this point not relevant.

 

Michael, thank you for your comments and suggested procedure.  The diode and the resistor were added around 2010 as was the wiring.  I doubt the diode is to suppress BEMF and has been added to allow only the correct polarity signal to release the commutator lock.

 

The commutator is definitely only 2 position.  When turned to the right (L1 activated) the disc shows clear in the port hole.  When turned to the left the TRAIN IN SECTION disc is dragged into the window in front of the BLOCKED disc and the associated tail appears below the box.   Physical moving the tail can make the TRAIN IN SECTION disc disappear to show BLOCKED.  Moving back to CLEAR) resets TRAIN IN SECTION disc so it is in front of the BLOCKED disc.  Hope that makes sense.

 

I am quite happy to ignore the added wiring and connect the two systems up as they would have originally be designed.  The problem I have is that I don't know for certain what that is at the moment.

 

Again thanks for all your help.

 

Neale.

[RailWest]

I /think/ that I am beginning to get there. ......:-)

 

With a 3-wire instrument the indicators at each end are wired in series so that when A turns his commutator and his indicator moves he knows that the one at B has move also, whereas if the line wire was broken nothing would happen.  Having the indicators in parallel could lead to the indicator at the pegging end moving correctly, but not the one at the far end if the line wire was broken. Indicators are held in the LH or RH position by a continuous current of the appropriate polarity from the commutator at the 'pegging' end.

 

With a 1-wire instrument it is the pulse of current from pressing the bell plunger which moves (or not) an indicator. Usually an indicator moves only if the current is of the reverse polarity to that last sent down the line (because the plunging chap has reversed his commutator). Any further pulses of the same polarity will have no effect, other than to ring the bell when passing through the red coils.

 

Incidentally...I note that the 50 Ohm resistor is attached (sadly out-of-sight in any of your pix) to the RH side of a brass 'pillar' which looks very similar to those to which the 'spring' contact for the commutator are attached, and not at all like the sort of terminal block used elsewhere for connections to wire going in/out of the instrument. I wonder of that is another modification and that originally SW1 contact 4 was connected to something else?

 

We know from the instructions that sending current down the line changes the white signal at the near end and the red signal at the far end, so those two must be in series down the line. But the reverse also must be true in the other direction. At the same time, ifthe red and white in the same instrument are in series, then both bells would ring whenever there was a plunge.

 

Therefore when A plunges to B, the current from the plunger at A must pass through A's white coil and down the line wire, but at the same time by-pass the red coil at A. At the same time also, the incoming pulse at B must pass thru' his red coil, but by-pass his white coil. This is where the NC contact comes into play somehow.

 

I wonder if the commutator lock coil was not part of Walker's original design? IMHO whatever controls whether or not it can be activated is clearly outside of the block instrument etc - for example, an N contact in a circuit controller on the lever for the Home signal and/or a contact on the arm proving relay for the Distant signal to provide for 'interlinking'. I suspect that you may need simply to bypass that altogether.

Edited August 16, 2021 by RailWest

[RailWest]

OK, a bit of a 'bodge' and some trial-and-error, but for initial testing:-

 

1.  You need two power sources (let's assume batteries) for each control box. Connect the two batteries in series, with a centre tap on the connection between the +Ve of one battery and the -Ve oof the other. Connect that tap to your Earth (ie a 'common return')

 

2. Connect the +Ve and -Ve outputs to J5 and J6. You will need trail-and-error from testing to find out which goes to which, but I would suggest starting with +Ve to J5.

 

3. J9 is your Line wire terminal.

 

4. Connect J7 to J1 .

 

5. J8 goes to the J3? NC contact.

 

6. J2 is connected to your Earth. You might want to bypass/remove the resistor initially.

 

7.  Mechanically disengage (can you tie it up out of the way?) the commutator lock.  Ignore J3 and J4.

 

8. Obviously, connect the 'L' to the 'L' of the other instrument and the same for the 'E' terminals.

 

Hopefully now you can at least send bell codes between the two instruments and also make the signal arms work :-)