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I realize this is a basic question but that's where I need to start. For an older 2 rail steam loco with tender, what is the wiring scheme?  A drawing would be great but an explanation will work.

I believe the tender can send power from one side/rail, and that is often routed to the loco through the drawbar. That connection goes to one of the 2 brushes. For a setup that does not have a second wire to the loco via a plug, what does the wire from the other brush connect to?  To the frame?

Thanks!

Eric

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Traditionally, straight DC 2 rail pickup is: right side rail from the engine, left side rail from the tender. Therefore there is one wire from the tender to the engine.

Check your wheelsets for continuity (insulated or not) on the engine and tender. Your result should confirm the explanation.

For example: the engine wheels and frame may be electrically 'hot' throughout, except for the insulated left side wheels. Insulated right side for the  tender.

A second alternate example would be power is picked up through iINSULATED wheels: right for the engine, left for the tender. The presence of wheel wipers on the insulated wheels would show this.

Last edited by PRR Man

If this is the Eric that had the 4-6-0 at Norm O scale, I have a thought.  Did that wire go to the head light, and maybe it became detached before or during disassembling.  Therefore the frame and engine body would along with the motor and light would be one pole and the other wire would go to the tender to complete the circuit.   I believe I have the same steam engine.  I would be willing to let take a look.  Hope this helps.

Erik

I have my replacement motor and want to install it. I'll try first to do this as it was wired previously., But I have other similar locos that do well with a two pronged tender plug.

Other than one brush running to the draw bar, how is the other side of the motor circuit connected?



Still on my basic questions. Thanks for any help.

@Eric G posted:

I have my replacement motor and want to install it. I'll try first to do this as it was wired previously., But I have other similar locos that do well with a two pronged tender plug.

Other than one brush running to the draw bar, how is the other side of the motor circuit connected?



Still on my basic questions. Thanks for any help.

If I understand correctly, the other goes to the engine frame. The important thing here is that the drawbar must be isolated so that it doesn't short everything out.

So one side (motor connection) is the tender frame, the other side is the engine frame. Wheels must be isolated on the correct sides.

Also, if you ever change to command control, you then must disconnect this motor and isolate it from the frames of the engine and the tender.

Thanks!  Yes, these are the same locos.  I don't understand how that wiring arrangement works, but I assume that the front drawbar wire is isolated from the one on the back. 

My new motor fits fine and I'm figuring out the universal shaft connection.  Are you able to send a good photo of yours?  It looks like a plastic tube with a pin through the shaft at both ends.  Mine seems home-made.  I hope to make this better.  Getting closer.  These are very nice looking locomotives IMO.

Eric

Guys,

I learned years ago, that a reasonable replace for a universal when you can't find one, is model air plane fuel line.    It comes in various grades and I use the more flexible.    You just slip it on the shafts and you are ready to go.    The flexible tubing works like a universal.    I have done about 4-5 old steamers this way when replacing motors.    I did not want to try to  solder the old universals on the motor shaft for fear of damaging the motor from the heat.    This is something you can use when the shaft sizes are not quite straight aligned with each other, or when you are dealing with different shaft sizes on the motor and gearbox.    I haven't bought any for  years.    I bought a foot or so for a few bucks the last time I bought some.

That's a good approach. What I replaced in this case was a homemade universal, and a ball connector that had been soldered as you describe. I wasn't able to remove it easily - another reason to use a different method.

Not sure how I would have properly fixed the worm gear shaft other than bracketing it in place in some fashion. Replacing the original looked challenging, assuming I could even find the proper part.

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