Records of a machine shop in St. Paul's Midway District that manufactured marine engines, transmissions, gears, and other products. Includes minute and stock certificate books, financial statements, photographs, and advertising samples. There is information about the firm's product lines, including its conversion of aircraft engines for marine use; documentation related to transmissions and related inventions patented by John D. Mooney and George P. Torgersen; and information about the history of the company, its 1980s downsizing, and the eventual closing of the business. Correspondents and organizations represented in the collection include company officials and stockholders, attorneys, and the Durst Division of the Regal-Beloit Corporation.

The firm was established in 1905 as The Auto Engine Works. Its name was changed in 1960 to Capitol Gears, Inc. The company went out of business in 1990.