Records of the company consist of the minute book of stockholders meetings, Hinckley's patents, bookkeeping records, and correspondence organized alphabetically by the name of the correspondent.

The correspondence of Hinckley Brake Company documents its efforts to supply railroad companies with new brake adjusters for passenger and freight cars. Letters contain requests for information on Hinckley products, orders, and discuss delivery, price, and technical issues. Correspondents include the Delaware and Hudson Canal Company; East Tennessee, Virginia & Georgia Railway; The Lake Shore and Michigan Southern Railway Company; Lehigh Valley Railroad; New York Centrals & Hudson River Railroad Company; New York, Ontario & Western Railroad company; New York, Susquehanna & Western Railroad Company; Norfolk and Western Railroad Company; Southern Railway Company; and Ulster and Delaware Railroad Company.

Another group of correspondence consists of letters from various metal works and car equipment companies which manufactured parts: Compressed Steel Shafting Works, Boston; Stanley G. Flagg & Company, Philadelphia; Hemacite Manufacturing Company, Trenton, New Jersey; Jackson & Woodin Manufacturing Company, Berwick, Pennsylvania; Westinghouse Air Brake Company; Morgan Spring Company, Worcester, Massachusetts; Philadelphia Drop Forge Company; Pittsburgh Forge and Iron Company; Port Chester Bolt & Nut Company, New York; J. H. Sternberg & Son, Reading, Pennsylvania; The Trenton Iron Company; and Wilmington Malleable Iron Company.

There also are domestic and foreign patent-related letters from the United States Patent Office, Haseltine, Lake & Co., London; and Pennie & Goldsborough, Washington, DC The files include documents from publishing companies and periodicals on railroads and car equipment: C.E. Howe Company, The Railway Directory Publishing Company, The Railway Equipment and Publication Company, American Engineer and Railroad Journal, Baker's Railway Magazine, The Engineering Magazine, Engineering News, Locomotive Engineering, National Car and Locomotive Builder, The Official Railway List, Poor's Manual of Railroads, Railroad Car Journal, Railroad Gazette, Scientific American, Street Railway Gazette.

The correspondence of the company's officers William du Pont, Charles K. Lennig, legal counselor C. Lowthorp, first president Howard Hinckley, and secretary and treasurer F. B. Stevens Jr. pertain to financial and organizational issues, legal matters regarding its dissolution, and personal stock issues. Folders also include a number of receipts, but the main body of receipts is found in the Receipt Scrap Book. Additional material related to the Hinckley Brake Company can be found in the General Correspondence and in William du Pont's correspondence with Charles K. Lennig in the Personal Correspondence Series.