Actually it took me several days of pulling out the few remaining hairs on my head to "fix" the problem. Reluctantly, I can't say I actually saw the cause of the derailments before what I did "fixed" it.
I am referring to a consistent derailing while running my eleven car set of Kato's "City of Los Angeles" Union Pacific set. I am building a layout in my garage that is considerably larger (eight Woodland Scenics modules) than the relatively small 3' x 5' layout I built and use in my dining area of my condo. I've got the track (mostly) laid out and have been running some locos just to check that all is well with my wiring, etc. All has been well ... including running a consist with two SD40-2's pulling 23 freight cars. However, when I tried my eleven car Union Pacific "City of Los Angeles" set pulled by two of my E8/9's, a derailment happened consitenly. I finally figured out which cars were involved and then, after some more head scratching, eliminated all but one car. I couldn't see what was causing the problem ... wheel gauge was fine .. the trucks swiveled just fine .. I was stumped. I tried it again a few times and eliminated one of the trucks so I'd at least found which truck was causing the derailing. Still couldn't see the problem. As I knew which truck was causing the problem I removed it, then took off the axles/wheels. Still could not see a problem (I should have looked more closely before removing the wheels ). Then, after a little hassle getting the wheels/axles back into the "cups" on the brass contact strips and screwing the truck back on, I tried the whole train once more ... Bingo! no derailments! I ran the whole consist again 6 to 8 times around the layout, across my double crossover, up the slight grade and down - at slow, medium, and full throttle. No derailment!
In conclusion I can only surmise that when I was doing some interior lighting work on that particular car a week or so before I ran the set on my new layout I must have pressed down on the car at my bench a little too hard and dislodged one of the axles/wheels from its little "cup" in the contact strip. My having taken it apart and put it back together "fixed" it. Of course, I'll never know for sure since I didn't notice any problem while yanking the wheels/axles off.
I hope my embarrassingly illogical procedure helps someone someday look more closely than I did at the position of the wheels/axles in their "cups".
Mike
Sometimes stuff just seems to happen, good or bad.
Always nice to have your problems behind you or at least one of them.
Hope you have some fun before the next one pops up.
Good luck,
Richard
I presume the "cups" the OP is referring to are what the metal wheels go into?
De-railments are VERY frustrating. Gotta appreciate when folks bring humility to this hobby. Thanks!
Good detective work in solving your problem.
Rich
Alton Junction