Atlas Yellow-box SD24

Model Railroader Electronics and DCC
1

I was cleaning and lubing the trucks on an old Atlas yellow-box SD24 when I broke a plastic part. It is a “Y” shaped shield that lays between the wheels and the band of copper for the wheel pickups that runs nearly the length of the truck. I believe it had been worn thin from rubbing between the center wheel and a solder point on the copper strip where the wire up to the motor is attached. Is this a critical part? It looks like the insulated wheels should deter a short circuit if the wheels were to contact the copper strip, now without the shield in place. I put the loco on a dc test track without the broken shield, and things seemed to run normally. Any advice is appreciated. Thanks.

  • Miles.
2

I believe that is more of an appearance item - the newer Athearn RTR locos have something similar. It hides the copper pickup/shiny metal truck side from view. If you compare the one with the missing piece to the other truck on the loco, you will probably notice the shiny metal being visible.

–Randy

3

That part is the wiper retainer. Here is a diagram:

http://www.hoseeker.net/assemblyexplosionAtlas/Assembly%20Explosion%20Atlas%20EMD%20SD24%2035%20Truck.jpg

Yes, it is important. The wiper conducts power from the wheels to the motor. Without the retainer, the wiper will eventually come off the truck.

Never seen one worn out, so I wonder if the soldered pickup wire was positioned incorrectly?