The Le Roi company of Milwaukee, Wisconsin, manufactured engines for a variety of industrial applications. In 1940, Le Roi acquired the Centuar Tractor Corporation. Centuar manufactured a line of industrial tractors using Le Roi engines. Notable was the Le Roi Tractair line. These tractors used a six-cylinder engine in which four fired, and two cylinder were used as an air compressor. Le Roi was purchased by Westinghouse (WABCO) in 1954, tractor production ceased in the 1960s.