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 coaster train, 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]
^Witter, Bret (2003). Carnival Undercover. Plume. p. 113. ISBN 978-0-452-28428-9.
^Pleasure railway structure
^Cartmell, Robert (1987). The Incredible Scream Machine: A History of the Roller Coaster. Popular Press. p. 117. ISBN 978-0-87972-342-2.
On a roller coaster train, the underfriction, up-lift, or up-stop wheels are a device to keep the train from jumping off the track under intense movement...
soon found in amusement parks across the county. By 1919, the first underfriction roller coaster had been developed by John Miller. Over the next decade...
innovations emerged in the early 20th century with side friction and underfriction technologies to allow for greater speeds and sharper turns. By the mid-to-late...
decades later as newer coasters began incorporating a third set of underfriction wheels, which further improved safety and allowed for more thrilling...
railway rides. John A. Miller introduced side friction coasters and later underfriction coasters in the early 20th century, which added additional sets of wheels...
Unlike its successor, it was a side friction coaster, meaning it had no underfriction wheels and therefore had milder turns and hills. It also had two individual...
sides (side friction or guide wheels) and underneath the track (upstop, underfriction, or underlocking wheels) as well as on top of it (road or running wheels);...
the rail, keeping the train centered. Up-stop wheels (also known as underfriction wheels or up-lift wheels): positioned under the rails to keep the train...
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