Ringfield wired wrong way round

[johnny wilko]

 Modellers help!

I picked up two Ringfield motors in as new condition on the net for £11 each. If its too good to be true, it probably is! They fit perfectly in the chassis and run smoothly when low DC is applied to the bushes in both directions. When testing with the multimeter it seems everything is wired back to front. There is approximately 30 ohms of resistance between the bushes which I think is fine but it is the right spring bush which is earthed to the chassis lead showing 0 ohms. The left spring bush shows 30 ohms to the chassis presumably developed by the motor coils. This seems to be the opposite to what I would expect. The the tender wheel sets have pickups both sides and as usual the left side has tyres on the driving wheels. The right pickups show zero to the left bush and about 40 ohms to the right bush.. The left side shows zero to the right bush and about 30 ohms to the left bush. Am I right in thinking this about normal for a DC motor.

I have wired up a few Ringfields following instruction from Flashbang and others with some success but I am confused with this one. Has anyone met this before or can offer advice as to how to DCC these motors safely? Sorry for the lengthy description, Hope it makes some sense. Thanks for reading.

[ColinB]

I suspect that you have a late 3 or 5 pole powered ringfield motor. The early ringfield motors picked up power via the axles on the tender and loco if it was a tender driven loco. If it was a diesel they used the front and back bogies axles. The issue with this was if you over oiled the axles the loco wouldn't work as there was no electrical contact. So later on they added pickups to the loco wheels and tender wheels. To do this on the tender made it a bit difficult to carry on with the existing arrangement so I am pretty sure they swapped the connections for chassis and live around. Now I imagine that the reason you ask is you want to convert this motor to DCC operation. If it is the really late type you will find that one of brush screws, screws thro the plastic plate into the chassis. What I did is tap the holes out that hold the brushes with a m2.5 or m3.0 tap and use really short laptop screws that only screw into the plastic and no further. You will read on a lot of sites to replace the earthing screw with a parallel thread nylon screw. Not a good idea to do this as it will eventually shear off as you try to jam a parallel thread screw into a self tapping screw hole.

[johnny wilko]

ColinB - Thanks for your reply and info. You are quite correct in that it is 5 pole and I want to convert to DCC. I think you are saying that it is OK to wire it so long as the right hand bush in this case does not connect to the chassis. Perhaps I need to swap the orange and grey wires for direction? Sorry to be hesitant but I do want to get it right.

John

[ColinB]

Yes you are exactly right the right hand bush must not touch the chassis and as you said swap orange and grey wires to achieve direction. When you have done the conversion check there is an open circuit on the multimeter between both brush holders and the rails. The other thing to note, the 5 pole ringfield draws less current that a normal ringfield but it is marginal for Hornby decoders, so fit a dcc decoder that has a current drive of 0.8 amps. I think Train O Matic, Zimo and several others support 0.8 current, Hornby's only go up yo 0.5 amps. Hatton's say theirs do but I found they don't when connected to a ringfield motor, it blew up immediately the loco stalled on a point. On my 5 pole ringfield based HST I do use a TTS decoder so it can work, but I am always worried it is very near its current limit.

[johnny wilko]

Many thanks ColinB. Good to have advice with background detail.

John