I suggest you spend 10 minutes watching this video from the La Mesa Club it will be time well spent.
If you can't find anything, try swapping the trucks with a car that doesn't have a problem. That will tell you if the trucks are the problem.
Good luck
Paul
The OP says the cars ran fine before installation of the Kadee couplers. Ordinarily I'd say that means that I'd look to the couplers as being in some way the culprit. However if installing the couplers meant removing the trucks, now there is another possible culprit that the trucks were not installed as suggested above: with one truck somewhat loose (but NOT sloppy) and one somewhat tighter (but not rigid or still). So let's say our OP tries the ideas mentioned above but still has the problem. Now I'd go back to looking at the couplers -- either the couplers themselves or something about the installation.
How could this happen? Well, if the coupler draftgear box is screwed into the underframe, is there a chance the end of the screw is running up against the car weight, and in trying to push the weight up, is actually bending the underframe down? That sort of thing. This can actually happen and in fact I am having that experience currently in installing body mounted KDs on a train set quality freight car. I need to drill through the weight or replace the weight in order to secure the coupler box with a screw.
Perhaps the screw was not properly centered in its hole and in trying to push the lid of the draft gear box towards the frame, is pushing the frame and the weight away.
Or -- and this is rare -- is there a chance the couplers are mating in such a way as to not have some "give" with nearby cars -- that is, they are grasping the other coupler too tightly -- so that the other couplers are in a sense lifting these cars up when track is uneven or around curves? Would some powdered graphite help on the mating surfaces of the couplers?
My instinct would be to remove the couplers, see if the cars still run OK through the problem areas, and then reinstall the couplers or perhaps a new set of KDs and see what happens.
Dave Nelson
Do the cars do this by themselves when pushed by hand, or only when being pulled or pushed in a train? I suspect that your coupler replacement may be the actual cause. If the couplers don't swing freely enough, they are binding and need to be loosened up. Since these are 50-foot cars, the couplers may not be able to swing far enough, which will push the cars sideways and force them off the track on curves. Watch the couplers closely as the car goes into the curve, and see if they reach their travel limit.
It takes an iron man to play with a toy iron horse.
Could be a lot of things. I just finished working a a bunch of my cars that derailed too often. I got them all to run right after a bit of tinkering. First check the swing of the trucks. If the truck or the wheel flanges touch the underbody of the car, even lightly, that is enough to put the car on the ground. Dremel off anything that is hitting. Fishbelly, coupler boxes, cross members, brake rigging. Check coupler height. Low couplers allow the gladhand to catch on things. Check wheel gauge, even minor out of gauge can cause all sorts of trouble. Check car weight. Light cars derail easily. Clean the wheels, bits of crud stuck to the tread will boost the flange over the railhead. Set truck screws, one end kinda tight, the other end looser. Kinda tight means screw it down til the truck won't move, then back off till it just swings freely. On the other end, do the same, but then back the screw off another 1/4 turn. This permits a bit of side to side motion useful in following uneven track.
David Starr www.newsnorthwoods.blogspot.com
Lee,Here's my suggestion..Remove the trucks and see if there is any underbody detail or plastic burr near the trucks that might be causing issues with the truck.If not then remove the body and carefully flip the frame over and check for any warpage.
Larry
Conductor.
Summerset Ry.
"Stay Alert, Don't get hurt Safety First!"
Good day all!
I could really use your help with two Atlas cars (a 50' hopper and 50' boxcar). Pls! Their metal trucks don't often touch the rails and derail at or near a curve. The curve isn't an issue b/c I can push a consist of other 50' cars w/o issues, and none of the cars had a problem before I installed Kadee couplers. I checked the track, couplers, and trucks to ensure there was no mis-alignment or binding. I also ran the trucks along the track before connecting them to the car with poper truck mounting screws. Weird! Thoughts and ideas? I don't want to scrap the cars.
Thanks,
Lee