In the Danish State Railways, the class F comprised three different types of tank locomotives with a 0-6-0T wheel arrangement. The four examples of type I were originally tender locomotives built in 1873 by the British company Hawthorn, Leslie & Company for the Jysk-Fyrenske Jernbaner. In 1889 and 1890 they were rebuilt into tank locomotives. Only eight belonged to type III, which were built by SLM in Winterthur in 1917 and delivered to Denmark after the end of the war. They were the only superheated steam engines in the series.
Type II accounted for by far the largest share with 120 locomotives. It was unusual that these locomotives were built by different manufacturers in different countries over a very long period of time. From 1898, ten were made by the Italian company Costruzioni Meccaniche di Saronno, which belonged to Maschinenfabrik Esslingen. Another 20 from Breda (Italy), Hanomag and Henschel (Germany) and Smith, Mygind & Hüttemeier (Denmark) followed until 1903. Two further batches of 30 and 45 each followed between 1909 and 1923 by Borsig and Hanomag (Germany), Frichs (Denmark) and Les Ateliers Métallurgiques Tubize (Belgium). Another 15 engines from Frichs followed in 1949.
The fact that 51 years after the first deliveries new locomotives were built in an almost unchanged design shows that even small tank locomotives with saturated steam were sufficient for shunting and that more complex designs were not needed. Even the Allan valve gear was retained, which at that point had actually been out of date for a long time. The only changes were more modern buffers and a larger coal bunker. In the meantime, the existing locomotives had been fitted with air brakes instead of steam brakes. Nevertheless, they were retired in the 1960s, since diesel locomotives were now available for shunting.
