Begun by D.W. (David) Onan in 1920, Onan has been a leader and pioneer in power generation equipment for more than 80 years and engines for 50 years. In 1989, Onan Corporation became a fully owned subsidiary of the Cummins Engine Company (now Cummins Inc.), the world's largest designer and manufacturer of diesel engines ranging from 55- to 2,700-horsepower for on-highway vehicles, industrial equipment, and power generation.