01-18-2011, 12:57 PM
At a recent workshop I attended on tuning cars and locomotives to eliminate derailing over less than perfect track, the man giving the clinic said that the "old three point" mounting system that has been "gospel" forever in model railroading doesn't work, never has, and never will because our models are just too light for the physics to work. It works on the prototype because of the weight. If you have a piece of rolling stock with the "three point mounting" and you "tip" it even slightly, the end with the tight truck will pull the wheels off the track. What he does to cure the problem is to set up the trucks just loose enough that when the rolling stock is sitting on a track, you can push the top of the car 1 scale foot without the wheels lifting off the track. In the event of a flat car or gondola, you probably need to secure a load to the car, perhaps with a rubber band to be able to deflect it at the normal "house car" height. If the car roof will deflect 1 scale foot without lifting the wheels, the car will handle rough spots in track work. If you can move it more than 1 scale foot, it will track fine, but may rock excessively. IN ho it works out to @ 1/8 of an inch is adequate to allow the car to handle rough track.