Another way to think of how this works is to look at crowned pulleys: https://woodgears.ca/bandsaw/crowned_pulleys.html https://woodgears.ca/bandsaw/crowned_pu

Another way to think of how this works is to look at crowned pulleys: https://woodgears.ca/bandsaw/crowned_pulleys.html https://woodgears.ca/bandsaw/crowned_pulleys.html In the train's case (if we ignore the gap between the wheels), the pair of wheels work like a crowned pulley, and the track finds center like a belt.