Quad skates

• abstract: The four-wheeled turning roller skate, or quad skate, with four wheels set in two side-by-side pairs, was first designed in 1863 in New York City by James Leonard Plimpton in an attempt to improve previous designs. The skate contained a pivoting action using a rubber cushion, and this allowed the skater to skate a curve just by leaning to one side.

以上来源于: WordNet