Atlas 21 inch passenger cars derailing

Are the couplers sticking and or moving freely??

Did your turn them upside down to see if trucks are moving and rotating freely?

Is the derailment occurring at the same point of the track with the same car and the same truck each time?  That happened to me with Lionel 21'' cars. The solution was changing the entire curved section with new Ross pre-formed 072 to replace my old pre-formed track that apparently had an almost imperceptible kink in it. On the one car and truck that exhibited the recurring problem with the old track section, I could never figure out why mechanically that one specific truck kept derailing. But when I replaced the entire track section with a perfect O-72 curve, that truck behaved properly.

I've got four of these cars. They run fine except I did have a problem with one coupler hitting a grab iron mounted to the bottom of the car end. In a curve it would cause the car to jump a little but not derail. I removed the grab iron and it fixed the problem.

Ken

I had problems with these cars at different spots and different cars all the time   Seems the overhang on them was hitting the DZ1000 switch motors in certain spots especially if there was an S turn near the switch   Changed the screws to fltheads on the switch motors and it worked

I am testing each car one at a time pulled by my best running PS3 Diesel.  I have a loop to loop.  Each car goes 2 loops at 43 SMPH. that is about a six minute run.  So far the four cars i tested did fine. I expect the other two will do the same.   So my conclusion is that I have all the clearance I need and track work is fine.   The problem becomes when I want to actually want to run a train.  I guess this would tell me the issues becomes when certain cars are coupled.   I am going to go back and add 1 car at at time and see where I get.  Last time i got to car 3 before i had trouble.   But now I know each car individually works

Surprisingly, wheel gauge is at issue, (most of the time).   O-Gauge wheels, that are pressed on the axle(s),  tend to be a bit too narrow for a lot of guides/ inside the rail plastic, that guides the trucks through switches, crosses, etc.   The more complex a layout, the more chance of a derail.  The large pizza cutter O-gauge flanges tend to ride, up and over plastic, causing de-rail.   I had/have a very nice Sears/Craftsman, battery terminal puller that works well to adjust wheel gauge.  There are other tools that can be used.  Be careful not to bend the axles.

I have 12 of these cars and for some reason the truck mounted couplers cause a lot of derailments in my Atlas #7.5 turnouts so I've switched them to body mounted Kadees and that solved the issue. I even tried cutting off all the thumbtacks on the couplers first but that wasn't enough.

I have some Lionel Up excursion passenger cars with kinetic couplers. When I got them they would derail on and off. I oiled the kinetic sliders and no more problems. They were were sticking etc.

Still have not had time to add cars one by one.  But I do kinda like the idea of replacing with Kadee couplers.  I am guessing i could find a good Youtube video on how to do it.

Do the Amtrak cars have adjustable length couplers?  I have the Atlas 21" CZ cars and I needed to lengthen the couplers to solve derailments on O72 curves.

Bob

They do not appear to be adjustable but I will add a pic in case I am missing something.

Each car will run by itself without derailing.  Even had luck with 2 cars.  The problem is when I get to 3-4 cars.  I thought I had one car identified as the bad apple but then a couple others starting acting up on subsequent runs.   It is not one specific spot.   It is not over a switch it has has been consistently on a curve and for no apparent reason.  It also seems to be the non coupler side of the truck in the back  of the car.     That is the only fairly consistent thing i have noticed.  2-3 times.  It is not "bad" jump off the track just a slight bump off.

Obviously frustrating because it is a beautiful train, not to mention expensive that I just can't run.  I appreciate all the input.

Yes they are adjustable. You remove the 2 black screws on either side of the roller in your photo then pull the coupler out maybe 1/2 inch then replace and tighten the screws. This will solve your problem. I find that the atlas cars need a larger gap than I would like in order to operate well.
Bob

Wow, I didn't even notice those screws was looking at the coupler.  

Thanks, that makes sense.   I will try that and let you know how it turns out.

Really appreciate that tip!

If the wheel gauge, couplers and pivot angle of the trucks check out OK and there is still a problem, I suggest adding weight to the cars.

MELGAR

The cars are plenty heavy, they just don't do well with the truck mounted couplers out of the box.

That solved it.   And they need every bit of that 1/2 inch.   Well now my passengers can't move car to car but at least they will stay on the track.

Thanks again Bob!