This forum is dedicated to Riding Scale Railroading with propulsion using other than steam (Hydraulics, diesel engines, gas engines, electric motors, hybrid etc.)
Another thing you might check out is if the trucks of your riding cars actually swivel freely with a full load. A truck that does not swivel freely will force the leedin wheel's flange into the head of the rail. I have seen the effects of a heavily loaded car causing a four car derailment . If the trucks moved more freely this probably would not have happned. Again , check the truck under full load.