Between 1897 and 1901, the metre-gauge Nordhausen-Wernigerode Railway received twelve 0-4-4-0T Mallet locomotives which were numbered 11 to 22. In fact, they were only the second locomotive order from the NWE after three 0-4-0T tank locomotives delivered in 1896. Nine were built by Jung and three by Mecklenburgische Waggonfabrik AG, which already built the first three tank locomotives. A feature was the outside frames with Hall cranks on the rear driver group, while the front drivers had inside frames.
Originally, all were used on the Harz Railway (Harzquerbahn). In World War I, six came to the army field railways and never returned to the Harz Mountains. In the fifties the five still existing, now designated class 99590 by the Reichsbahn, came to the Selke Valley Railway due to the arrival of the new 2-10-2T locomotives on the Harz Railway. In 1975 and 1990, one locomotive each was scrapped. Today three are still existing, with none of them currently operational.