It is not just us with out of gauge wheels. Now, "Defective loose wheels found on NS rail cars - ABC", "this specific model and series of railcars had loose wheels, which could cause a derailment - recently manufactured wheels - NS". "These wheelsets are at an increased risk of out of gage derailment". So, prototype follows our models, check your wheelsets for correct N-Gage spacing! - Tonkphilip
I've seen the term "loose wheel" over and over in the new today. What does "loose wheel" mean on a train car? My guess is that they go out of gauge, too narrow, but how does that happen?
I wonder if the wheel face and axle machining were off just a bit too much, and the factory didn't catch the out of tolerance condition? The axle might press into the wheel, but the clearance too loose to hold properly. Over time or in lateral loading situations, the axle could basically fall out, if I'm understanding this correctly.
It's kinda like the old steam engines putting a tire on a driver. If the hole in the wheel is a bit too big, when the wheel heats up from brakes being applied it expands, that makes the wheel loose on the axle.
