The rich heritage of the Hercules gas engines began after the purchase of Sparta Works in 1913. In that year they built a factory in Evansville, Indiana and became the company that has been at the forefront of industrial engine manufacturing since 1915. Sparta Works changed their name to Hercules Motor Manufacturing Company and quickly gained recognition for their exceptional engines designed specifically for trucks.

In 1923, the company underwent a reorganization and emerged as Hercules Motors Corporation, expanding their expertise in gas and diesel engines. The large catalog company Sears Roebuck was their largest customer, selling their private label Economy engines, often with the associated equipment the engine drove.

Throughout the interwar period, they successfully catered to the needs of truck, tractor and various equipment operators. Additionally, the company played a crucial role during World War II, by producing an impressive 750,000 gasoline and diesel engines for Allied military vehicles, ships and equipment.

The most prominent engines manufactured by Hercules are Hercules, Jaeger, Arco, Economy, Saxon, Thermoil and perhaps others. They were manufactured from 1913-1934.