Roller coaster up-stop wheels that hold cars to the track
A roller coaster wheel assembly. The underfriction wheels are on the bottom. The three sets of wheels clamp onto the track.
On a
roller coastertrain, the underfriction, up-lift, or up-stop wheels are a device to keep the train from jumping off the track under intense movement.[1] The design was patented in 1919 by
John A. Miller.[2][3]