How roller coasters stay on their tracks


How roller coasters stay on their tracks
How roller coasters stay on their tracks
Animation of the underfriction, or upstop, wheel, patented by American designer John Miller in 1919. It keeps the roller coaster on track, as does the guide, or side-friction, wheel, while the road, or running, wheel rides astride the track and carries the load.
Encyclopædia Britannica, Inc.