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Wiring of Midland Railway Pegger/Non pegger, and Block Bell

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Wiring of Midland Railway Pegger/Non pegger, and Block Bell

Unread postby PSB Supervisor » Sun Mar 6, 2016 9:44 pm

Hi,
I wonder if anyone can assist ? I didn't spot the answer in the forum so far.

I have purchased a Midland bell, a single non-pegger block, and am planning to get hold of a Midland single pegger.

Could anyone assist with the correct voltage and wiring connections please ? The plan is to wire the the bell - so that the tapper will ring it

As for the block, I would like to conventionally wire it and would appreciate being guided by someone who knows, so any help would be appreciated.

Many thanks in advance.
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Re: Wiring of Midland Railway Pegger/Non pegger, and Block B

Unread postby John Webb » Mon Mar 7, 2016 10:32 am

Wiring up our MR Rotary blocks at St Albans South we used 12volts for the bells - this was more reliable than the 5volts used for supplying the instruments. The 5v was fed through appropriate resistors to the block instruments so that they received around a volt or so - this gave good deflection without driving the needles hard against the stops. You may need to experiment a bit to determine what suits your instruments.

Additional: Will look up my circuits in due course re working the bell via the tapper - this will require some internal work to the bell/tapper unit.
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Re: Wiring of Midland Railway Pegger/Non pegger, and Block B

Unread postby Mike Hodgson » Mon Mar 7, 2016 12:40 pm

The conventional arrangement is for the tapper on one bell to ring the bell at the next box, so by definition trying to ring it with its own tapper CANNOT use conventional circuitry. Similarly, the conventional arrangement is to have a non-pegger at one end of the section and a pegger at the advance end of the section, mirrored by exactly the same for the opposite track. So the conventional circuitry assumes you really have two pairs of instruments!

This type of equipment is called 3-wire 3-position block because it uses one one wire on the telegraph poles for the each direction plus a third wire for the bells (which are of course used to signal trains in both directions). The battery at one end of the line runs via the tapper to the bell at the other. The return circuit is completed either via the earth or an additional return line wire. All you normally hear at your own end is the clicking sound of the tapper.

AS John says, 12v is usually used for blocks, but may be increased because of resistance of the telegraph line.
The blocks are generally OK on 12v, but will work fine on a lot less, perhaps as little as 2v. However you need a +V and a -V supply (use two batteries of your chosen voltage), since the commutator is designed to connect one polarity to deflect the needle to the Line Clear position and the other to Train on Line. The pegger and non-pegger dials are connected in series via the commutator to this supply, using the earth return circuit, same as the bell. If the telegraph line gets broken in the simple standard circuit, the dials will both drop to Normal, so both boxes will know if the fault develops whilst there is a train about.

Hope this helps.
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Re: Wiring of Midland Railway Pegger/Non pegger, and Block B

Unread postby John Webb » Mon Mar 7, 2016 4:22 pm

My neat diagrams are of course directly related to St Albans South, and would not be of much use to you, so I've sketched a couple of diagrams for you. This is the usual circuit for the bells:
Image
Depressing the tapper at one end connects the line to the local battery and rings the bell at the far end via the 'back' contact of the tapper at that end.

The modification to ring the bell using the local tapper is fairly simple:
Image
The bell is connected to the tapper's middle instead of the 'back' contact; this can be done by simply adding a short length of wire to link the two together. Vs is your power supply. I've put in a reverse-biased diode across the bell - this will eliminate the back-emf generated by the bell's coil and save wear and tear on the contacts or possible damage to your power supply. Virtually any diode from the 1N400X series will do.

Hope this helps.
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Re: Wiring of Midland Railway Pegger/Non pegger, and Block B

Unread postby PSB Supervisor » Mon Mar 7, 2016 5:32 pm

John,

That is magic ! Thank you.

With regards to the Block, if I understand correctly I will only need a single wire, with a power supply at each block ?

I have a single repeater, and hope to wire it to a single pegger. Neither of these has a block bell.

http://i.ebayimg.com/00/s/MTYwMFgxMDcw/ ... 5/$_57.JPG

http://i.ebayimg.com/00/s/OTQ1WDcwOQ==/ ... 8/$_57.JPG
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Re: Wiring of Midland Railway Pegger/Non pegger, and Block B

Unread postby John Webb » Mon Mar 7, 2016 9:14 pm

My pleasure. The non-pegger block instrument merely repeats what the pegger at the other box has been set to. In the absence of an earth return you will need two wires and a small power source (possibly two single-cell batteries) giving a reversible polarity. Here's a diagram of the signal arm repeater set-up which, if you substitute the pegger contacts for the signal arm switch contacts, will give the required result:
Image
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Re: Wiring of Midland Railway Pegger/Non pegger, and Block B

Unread postby PSB Supervisor » Mon Mar 7, 2016 10:27 pm

Or I guess even easier is to install an earth return ?
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Re: Wiring of Midland Railway Pegger/Non pegger, and Block B

Unread postby John Webb » Tue Mar 8, 2016 9:25 am

I must admit I thought you were setting yourself up a small self-contained demo and would be directly wiring them together. If your instruments are a distance apart, you will have to balance the simplicity of two wires against the establishment of adequate earths at each end of the run. On balance I'd stick with two wires - less risk of strange currents being introduced via the earth connection and simpler fault-finding.
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Re: Wiring of Midland Railway Pegger/Non pegger, and Block B

Unread postby John_S » Tue Mar 8, 2016 8:56 pm

John Webb supplied a diagram and wrote:
Here's a diagram of the signal arm repeater set-up which, if you substitute the pegger contacts for the signal arm switch contacts, will give the required result:]

This is perfectly correct, and has the block fed by a power supply which provides both + and - relative to 0V. From a modern perspective, this is probably the easiest way to do it. However, there is also another way of wiring a simple block instrument, which was probably more common in the past, and which used a commutating battery. There is a diagram here: http://www.lymmobservatory.net/railways ... r/lner.htm John's arrangement does not use the 'B' contact in my diagram. (There are also diagrams for some LMS instruments here, though it's probably easier to start with the descriptions of the LNER ones).
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Re: Wiring of Midland Railway Pegger/Non pegger, and Block B

Unread postby PSB Supervisor » Wed Mar 9, 2016 7:03 pm

I am thinking of using a centre-tapped 240v/6v dc transformer, so that I don't have to worry about batteries. also the blocks will be close enough to wire as per JW diagram. If I use one supply 6v for the bell and the other for the block instruments that should work out fine.
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Re: Wiring of Midland Railway Pegger/Non pegger, and Block B

Unread postby John Webb » Wed Mar 9, 2016 7:27 pm

PSB Supervisor wrote:I am thinking of using a centre-tapped 240v/6v dc transformer, so that I don't have to worry about batteries. also the blocks will be close enough to wire as per JW diagram. If I use one supply 6v for the bell and the other for the block instruments that should work out fine.

I suggest that you treat the two outputs as two batteries and put in series. Run the bell from the 12v total from the two supplies. Run the indicators from the two power supplies, but you will need a series resistor to drop the voltage to the indicators - something about 5 times the resistance of the instrument - which should be marked on it somewhere.
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Re: Wiring of Midland Railway Pegger/Non pegger, and Block B

Unread postby Richard Pike » Wed Mar 9, 2016 8:47 pm

Richard..
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