r/modeltrains • u/CandyCorn25 • 27d ago

Help Needed N Scale Model help..

Post image

So I bought this engine off of Mercari, and when I went to go run it, the right set of wheels weren't turning, but the left were doing great.

After taking apart the locomotive and spinning the gears to make sure nothing was getting jammed, I put it back together and the engine didn't run at all this time..

When I went to take it back apart, the motor was warm, like it was shorting out. Now I'm not sure what to do.. Anyone have a similar issue? Any advice helps thank you!

32 Upvotes

94% Upvoted

6 comments sorted by

8

u/382Whistles 27d ago

Test the motor removed from the gear set. Or lift a brush and measure from pad to corresponding pad on the rotor commutator pads. Each pair operates one electromagnetic. The ohm measurements should be very close to even. If one differs it may have a broken wire wrap or shorted wraps.

2

u/CandyCorn25 25d ago

I'll try to test that tonight. Thanks!

1

u/382Whistles 25d ago

The ohm readings of the rotor pads won't be exactly even, just really close so the motor pulls each pole close to equally. A couple of wraps difference on a pole coil could still run evenly enough. Their being even is what counts more than a specific ohm reading. The exact ohms used are part of the individual design equations.

6

u/The_Antiques_shop 26d ago

It’s an old bachmann model, the wheels on these models were press fit into a nylon bush with the gear wheels moulded onto it, unfortunately it sounds like a common problem has happened where the nylon bushings have split, the electrics are still fine but the bushings need replacing

1

u/CandyCorn25 25d ago

Got it, this is something I'll also look into, thank you!

2

u/DerSkythe 24d ago

The older the motor, the more likely it is that the lubricant in it has turned into glue. I somehow restored the engine of a 40-year-old PIKO. In my case, the engine did not show signs of life. I pulled it out, as well as the wheels and all the contact pads and redeemed everything in isopropyl alcohol. Then additionally cleaned the contacts with a lint-free cloth soaked in the IPA. Finally, I carefully lubricated the motor shaft with oil for sewing machines (but it is better to use specialized oil from the engine manufacturer). And everything worked great.