Does the engine "short out", as in cause a short-circuit and trip the breaker on the transformer, or does the engine simply stall, or stop?

Thanks for replying. It does not actually trip the breaker. The train stops, and all the accompanying bells, whistles, and lights fail. (Sorry for my inaccurate description.) 

  

Check the track section with a meter?  Check your pick up rollers?

You probably have dirty track or a poor connection.  First, I'd clean the rails with a cloth (NOT STEEL WOOL) that has something like Goo Gone or track cleaning fluid on it.  If that doesn't do it, then look at the small brass tabs on the undersides of the Realtrax pieces and bend them into shape so that when the pieces are connected the tabs from each piece touch each other.  If that doesn't do it, then it's just because the crossover has a plastic frog and the pickup roller spacing on the engine isn't great enough to still get power when going over the frog.

I had a problem similar to this with a Lionel Junior Hudson crossing over O27 switches.  The switches didn't have a continuous center rail, but I imagine the theory is that one of the two pick-up rollers would have contact at all times.  Not so with the Junior Hudson....when I rolled it slowly over the switch, I could see exactly the spot where neither roller was in contact with the center rail.  Maybe the cross-over track has the same problem??? 

I had a very similar problem where my Lionel RTR 4-4-2 would stop on the crossover if going at a slower speed.   Everyone said to focus on the center rail.  But after checking with a volt meter, I found the problem not to be the center fail but the outer rails.   What was happening was the flanges on the driver wheels were hitting the bottom on the crossover and ever so slightly, lifting it up the track.  I ended up filing or sanding some of the material away to give room for the deep flange.   Problem solved.

Push the engine slowly over the crossing and watch for the engine light to go out.  Then check where the rollers are positioned on the track.  If you have a DVM, check for voltage at both locations on the track.  I suspect one of your rollers may have a broken wire.  If so, the good roller will be positioned over the area where there is no voltage which will probably be in the middle of the crossing

 

Earl

Update?