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.
Tractair.com - history of the Centuar and Le Roi tractors