Hercules Engine News

Including Economy, Arco, Jaeger & Thermoil

6 HP Cummins

# 77C, 6 HP Cummins.

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20601 Old State Road, Haubstadt, Indiana 47639

The Hercules Thermoil story isn't complete without discussing 'The Cummins Connection.' Concurrent to the design and development of the 1, 3, 6 and 8 HP Thermoil engines at Hercules was the intense interest in diesel engines by a young Columbus, Indiana man: Clessie Cummins.

He had turned his employer's private garage into a small machine shop. By some connection, he was doing some parts machining work for the Hercules Gas Engine Company. He apparently was keenly aware of the design work being done on the new Thermoils. He made a trip to Chicago in October, 1918 to the R. M. Hvid Engineering Company to see about obtaining rights to also produce the Hvid type engine. The licensing fee being out of his reach, he returned to Columbus. He convinced his employer and others that such an engine would become popular, and with their backing formed the Cummins Engine Company on February 3, 1919.

The first engine Cummins produced in April 1919 was the 6 HP model C. They looked very similar to the 6 HP Thermoil Hercules was building for Sears. Yours truly has seen #77C and knows of #142C. Both are 6 HP Cummins, and they appear identical to the 6 HP Thermoil in the previous story. The only exceptions being the water hopper casting shape and the absence of pulley lugs on the flywheels. By February, 1920, 22 had been sold. Apparently only 100 or so were produced. Only two are currently known to exist. #77 is shown here in a rather poor picture yours truly took at the 1981 show at Portland, Indiana.

Hercules (1919) was now building the 6 and 8 model U Thermoil for Sears, but lacked foundry capacity to expand into the and 3 HP sizes. Hercules personnel suggested that Mr. Tippet from Sears contact Cummins to build them. Sears awarded Cummins a contract to build 4500 of the two small sizes. It is very likely that the design for these engines was done at Hercules sometime earlier. The 1 HP size Cummins Thermoil is shown here (above right).

An early piece of Cummins literature states that Cummins engines were built in l, 3, 6 and 8 HP sizes, but it is believed that the 6 HP was the only size actually built before the Sears opportunity came along and the Cummins brand engines were phased out. Serial number data available indicates that Cummins produced about 1500 (mostly in 1920) of the two small sizes before the bubble burst and the market for them died. So far, at least 19 of these 1 and 3 HP size are known to still exist. Cummins also produced that same year some $10,000 worth of 'injectors' for Hercules to use on the 6 and 8 HP Thermoils that they were building. That translates into about 1000 injectors. Some injectors found on the Hercules Thermoil 6 and 8 HP sizes have C E C (Cummins Engine Company) stamped on the rim of the injector body.

A longer discussion of the Cummins Engine Company is beyond the scope of 'Hercules Engine News.' If you desire some information, check with your library for Clessie Cummins book, My Days with the Diesel. The Indiana Magazine of History, December 1986, pages 303 to 333 contains an article by John Rowell who was the historian for Cummins. It is titled, The Diesel Came, to Indiana in the Horse and Buggy Days. There were also several related articles in the Cummins employee magazines.

At least two advertising pieces and one instruction book on these early Cummins engines exist. They were called 'Cummins Oil Engines.' The small circle inset is of the fuel spraying from the injector cup into the combustion chamber. The text and illustrations are often strikingly similar to that put out in literature for the Thermoil brand engines.