From around 1890, express locomotives with a 4-4-0 wheel arrangement became established in Germany, as had been procured in large numbers in North America for a long time. Not only were they more powerful than locomotives with a 2-4-0 wheel arrangement, they also ran smoother due to the leading bogie. This paid off particularly well, since the passengers increasingly demanded higher travel speeds, which were higher than the maximum achievable speeds of many locomotives from the past.
In Württemberg, shortly before the turn of the century, many locomotives with a 1B wheel arrangement were still in use, which had problems fully meeting the current requirements and, above all, would no longer have been able to cope with the traffic at the beginning of the new century. Thus the type AD was developed, which was built a total of 115 times from 1899 to 1909. The locomotives were powered by a two-cylinder compound engine, which acted on the first coupled axle. The coupled wheels were relatively large with a diameter of 1,800 mm and enabled a top speed of 100 km/h and continuously 90 km/h. A distinguishing feature was the connecting pipe between the two steam domes.
In 1907, an AD was equipped with a superheater and simple engine, which enabled an increase in output of around 20 percent despite the boiler pressure dropping from 14 to 12 bars. Thus, the other 17 locomotives were also designed using superheated steam and were designated ADh. From about 1920, the first examples were retired, so that the Reichsbahn only took over 24 AD and 14 ADh. To distinguish them from each other, they became the classes 1316 and 1317. The last of the saturated engines was retired in 1928 and the last superheated engine four years later.
