The Pennsylvania Water & Power Company formed in 1910 to finish construction of the Holtwood hydroelectric facility along the lower Susquehanna River in Pennsylvania. The company achieved numerous advancements in hydroelectric and steam power development in the early twentieth century, and helped bring about the electrification of Baltimore and, later, much of the Chesapeake and eastern Pennsylvania area. The records largely consist of correspondence to and from Pennsylvania Water & Power's chief engineer and later president, John Abbet Walls, and other company heads relating to operations, customers, dam construction, and numerous subjects associated with the hydroelectric industry.

Richmond Machine Company is an equipment manufacturer located in North Philadelphia. In around 1953, the Richmond Machine Company acquired the American Pulley Co. for the use of its patents. The American Pulley Co. was a power transmission equipment manufacturer which had its start as a pulley provider in Philadelphia, Pennsylvania, in 1892. This collection consists of two parts, the American Pulley Co. and Richmond Machine Company, the latter comprising only a small portion of the records. Within the American Pulley Co. series, researchers will find photographic prints of various hand and lift trucks, power transmission equipment, and non-mechanical products produced and distributed by the American Pulley Co. Researchers will also find images of facilities and employees demonstrating equipment for advertisement purposes. This collection transitions to the Richmond Machine Company, which bought the American Pulley Co. around 1953 and incorporated these photographs into their personal inventory. Included within this series are instructions, guides, and videos pertaining to drum and barrel reconditioning. Produced for both outside companies and personal sales, products within this collection demonstrate the role the American Pulley Co. played in early industrial development. Researchers interested in power transmission equipment would find this collection useful.