Friedrich Krupp Maschinenfabriken AG built a total of 15 type St 309a low-loader wagons for Deutsche Bundesbahn (DB) between 1957 and 1966. These wagons were specially designed for transporting small but heavy goods. With a dead weight of approximately 15 tonnes, a maximum payload of 21 tonnes was possible. Due to the compact design, which was dominated exclusively by the curved solebar, it was not possible to equip the vehicles with a compressed air brake. To secure the wagons when they were parked, it was only possible to lock one wheel set via a handbrake. In addition to DB, the Dutch State Railway also purchased five of these vehicles from Krupp for the same purposes from 1962 onwards. In Germany, the last six wagons were retired from the DB AG inventory in 2004.
