underfrictionEtymologyFrom under- + friction.nounA system for preventing a rollercoaster train from jumping off the track while in violent motion, using additional wheels under the track.“Altho having 5,000 feet of track, every inc of the route is full of thrill and sensation. Winnwood used the 1922 construction with the safety underfriction and the second coaster was the kids' and adults' "Picnic" type, with around 1,100 feet of track.”