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SLIDER: 1950 Cummins Diesel Special

According to American magazine Speed Age Cummins achieved three firsts: the conception of the world’s first diesel automobile; the first diesel speed record; the first diesel racing car.

Clessie Cummins was born on 27 December 1888 in rural Indiana. In the 1910s he went to work as chauffeur and mechanic for William Irwin, a banker in Columbus, Indiana. In 1919, with financial help from Irwin, Cummins founded the Cummins Engine Company, initially to make a 6 hp engine under a licence from the US owner of compression-ignition patents, R. M. Hvid Co., for use on farms. This brought in insufficient income, so Cummins tried the yacht market – and that disappeared during the Great Depression. Undaunted, Cummins convinced Irwin to install diesel engines in the fleet of trucks in Irwin’s Purity Stores supermarket chain in California. This venture made money.

Cummins’ first successful engine design was the Model F of 1924, used in boats and commercial road vehicles. Further developments consolidated his success before World War II, but more was to come: during the war, the American military bought every diesel engine they could for the 1944 invasion. Post-war, sales of engines for civilian trucks then assured the further growth of the firm.

Clessie Cummins was also fascinated by racing. In 1911, he served on the pit crew for Ray Harroun’s Marmon Wasp racer, which won the inaugural Indianapolis 500 race. Then, in 1931, Cummins set the diesel speed record at 100.755 mph (162.150 km/h) on 7 February on Daytona Beach with a self-built 361 cubic-inch four cylinder, three-valve, 85 horsepower Model U marine diesel that he installed in a Model A Duesenberg. The same car, slightly modified, was entered in the 1931 Indianapolis 500 race. It averaged 86 miles per hour and completed the race on one tank of fuel, without any pit stops.

Cummins returned to Indianapolis in 1934 and again in 1950 – with the car in this Slider. The Cummins Diesel Special wore race No. 61. Because of its green colour, driver Jimmy Jackson referred to the car as the Green Hornet. The car was built on a modified Kurtis Kraft chassis and was powered by a supercharged inline-six engine based on the Cummins JBS-600 truck engine. The car used disc brakes and independent front suspension, both firsts at Indy.

Green Hornet qualified for the Indy 500 at 129.208 mph, the slowest qualifying speed of the grid. During the race, the car was retired on lap 52, while in 29th place, because of issues with the engine’s vibration damper and supercharger drive. The car was repaired, and at the Bonneville Salt Flats on 11 September 1950 Jackson and the Green Hornet set six International diesel speed records.

In 1955, Cummins had to leave the company he created, retiring from the position of Chairman. He had managed to hold onto some key patents and formed Cummins Enterprises Company later that year. He moved on to work for the Allison Engine Company in California. He died on 17 August 1968.

Picture courtesy of the Richard Roberts Archive

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