Railroad cars don't have differentials and travel on parallel tracks. How?
https://www.reddit.com/r/Skookum/comments/47sbri/richard_fey...
Railroad cars don't have differentials and travel on parallel tracks. How?
https://www.reddit.com/r/Skookum/comments/47sbri/richard_fey...
For those that don't read the link, by having conical wheels.