The Allis-Chalmers Manufacturing Co. of West Allis, Wisconsin, is an American company known for its past as a manufacturer with diverse interests, perhaps most famous for their bright Persian Orange farm tractors. The company eventually divested its manufacturing businesses to become Allis-Chalmers Energy. Allis-Chalmers Energy then merged with Seawell to form Archer, a drilling and well service company.

Allis-Chalmers first entered the manufacturing business as E.P. Allis of Milwaukee in the 1840s. They made waterwheel, sawmill and grindstones. While originally incorporated in Delaware, the company soon became a major manufacturer of steam engines and industrial equipment in the Milwaukee area after merging with other firms—Fraser & Chalmers were a large steel and mining retort manufacturer. The company's presence in Milwaukee became so large that its plants were once used as a landmark there, and, in particular, its "west" plant may have lent its name to the city of West Allis. Allis-Chalmers entered into the farm equipment business in 1914 at about the time of the World War I. The company would also play a major part as a manufacturer in the World War II building pumps for uranium separation as part of the Manhattan Project and building electric motors for U.S. Navy submarines. Allis-Chalmers also built triple expansion marine steam engines for Liberty ships.