K-Line smoking caboose/ucs track

Wow that's good timing.

The profile of the center rail roller on the K-Line caboose is such that it is making contact with the center rail and the one control rail that shares it's high side connection with the magnet as the coupler rides over the sweet spot for uncoupling.

Substitute a narrower roller assembly, or chamfer the outside edges of the roller to keep it off the operating rail.

That's one I haven't seen.   I had a locomotive that a wide roller would short going across a switch, I guess this is a variation on the theme.

some on the mth smoking tank cars have a wide roller, and would short out.  I ground a chamfer on each side of both rollers, no more problem.

Hmm...  I have an MTH smoking tank car, but so far it hasn't shorted out.  I'll have to take a look at the rollers...

One could also rewire the UCS such that the uncoupling magnet is on a separate circuit, rather than sharing a connection with the control rails.

When I still used a UCS I wired it so the magnet was separate, and the control rails were not connected unless the "operate" function is activated.

The only drawback is that you could no longer uncouple postwar rolling stock that has sliding-shoe coil couplers.

Thank-you all for identifying the problem and offering a solution.  My follow-up question is how to best chamfer the roller?  Have thought about a file or perhaps using a ginder on my dremel?

Is it best/necessary to remove the roller to work on it?  If so, how is that best done?

Again thank-you for your comments/suggestions.

Jack

You probably don't need to take off much - my first instinct was to use the Dremel.