In 1889, a rail line was built to the elegant spa of Langenschwalbach, now known as Bad Schwalbach. The line ran to Wiesbaden and had grades of about 3.3% as well as curves with a minimum radius of 200 meters / 656 feet 2 inches. The Prussian State Railroad had a new type of passenger car built especially for service to the spa. Although commuter cars at that time almost always had two or three rigid axles, the Langenschwalbach cars were equipped with 2-axle trucks, initially with a short wheelbase of 1,650 mm / 65" and a small wheel diameter of 740 mm / 29-1/8". However, it was soon apparent that a wheelbase of 2,000 mm / 78-3/4" and the usual wheel diameter of 960 mm / 37-3/4" did not negatively affect the riding comfort of the cars. The bodies for the cars demonstrated the first elements of lightweight construction. The designers used the exterior sheet metal for the walls as a load-bearing element. Tubular shapes served as cross girders for the car bodies. The design proved so effective that it was used for 35 years with few changes. The first Langenschwalbach cars were placed into service in 1892. Initially, only 1st to 3rd class seating was offered. From 1907 on, the various state railways also placed 4th class cars of this type into service. Combination mail and baggage cars came later. As the cars were quite popular with the public, they were soon in service outside of their home district. The German Federal Railroad retired these cars in the Fifties. Numerous cars found new work in maintenance train service.