I still wonder why Lionel would make them with such sloppy tolerances.
Manny, the story has it that this was done for shipping. The trucks were turned so the coupler was turned inward beneath the train car, so the rivets had to be loose enough for this to be done.
At some point during the MPC or LTI eras, the box design was changed so that the trucks with couplers could be left in the normal outward position. And yet the rivets can still be loose.
Just for a clarification, the loose rivet truck mounting is more of a derailment issue when pushing a train backwards. All the weight is then on the couplers, so when going backwards into a tight curve, that loose rivet mounting is going to naturally allow the truck to move upward on the inside wheel set, thus causing the derailment.
But folks also ran their trains shorter back in those days. The advent of the fast angle wheel during the MPC years allowed for less friction thus the ability to run longer trains without damaging the motor of your locomotive.
Outside of poor track, there are some other causes for derailments that I personally have experienced:
- Wheel sets out of gauge... more of an issue when buying a used train car that may have had wheel sets replaced, or originally had plastic wheel sets. I once bought a bulk parts bag of fast angle wheel sets and was quite surprised to see how much variety there was in the gauge of the wheels. I've discovered there can be some variation in wheel set gauge and you'll be alright, but NOT with wheel sets on the same truck. You want the gauge of the wheel sets to be the same on one single truck.
- Knuckle couplers. Although all the manufacturers use basically the same design for the knuckle coupler, there are subtle differences. For example, knuckles and pins from one brand will not fit properly on a another brand of train car. In the case of the Industrial Rail cars, the space on the coupler where the pin inserts to hold the knuckle is much thicker than on other brands. So this can cause the couplers to bind when running backwards on tight curves, thus causing a derailment.
Staying with couplers, another possible cause is flashing on plastic trucks, particularly on the knuckle itself. Also the space within the closed knuckle coupler can be an issue.
But again, over the years, there have been a number of companies making trains, and the designs used on their couplers - while basically similar - are all subtly different. The only real way to potentially avoid this issue is to run train cars all made by the same manufacturer.
To add another fly to that ointment, with all the multiple vendors being used today in Chinese production of trains, there's no guarantee that rule of thumb will even work, as the companies could today be getting parts from any number of vendors. Up until the early 2000's, all the trains made in China were all made pretty much by one single facility: Sanda Kan. When that company announced a major shakeup, all the train makers were left scrambling to find another Chinese vendor to manufacture their trains. I don't know how accurate this info is, but I've heard there up to seven different vendors (or Chinese plants) making trains and components for Lionel trains.
