Prussian S 10¹

Since the S 10 was found after a short time to consume a lot of water and coal, the development of a more economical locomotive with a compound engine was started. Although the designation suggests otherwise, the S 10¹ was not related to the S 10 in terms of design. The class only included express locomotives with a 4-6-0 wheel arrangement, in reality the S 10¹ was a completely new design and was not based on the P 8 like its predecessor.

The power plant was designed according to the de Glehn design, which means that one pair of cylinders acted on the first driving wheel set and the other on the second driving wheel set. So, in contrast to most German four-cylinder compound steam locomotives, the S 10¹ had the low-pressure cylinders on the inside and the high-pressure cylinders on the outside.

Although the locomotives were only completely convincing after a few modifications, the consumption was significantly reduced compared to the S 10. In addition, with an indicated power of around 1,400 hp and a drawbar power of 1,000 hp, they were the most powerful Prussian express locomotives, since no Pacific locomotives were procured in Prussia. 152 of the original type were built, 17 of which were for Alsace-Lorraine. Of these, twelve had an engine of the Borries design, in which all cylinders acted on the first driving axle. 

Although the first design performed well, there was still potential for improvement. Most notably, the arrangement of the cylinders has been changed to make them more easily accessible for maintenance. In addition, weight savings were implemented in order to be able to install a feedwater heater with the same axle load. As a result, the new locomotive was even more powerful than the first type, so express trains of 500 to 600 tonnes were hauled in everyday service. Although it was slower than some Pacific locomotives from other railway companies with a permitted speed of 120 or 110 km/h, one reached 152 or 156 km/h depending on the source. A total of 115 locomotives of the 1914 variant were produced.

The Reichsbahn took over 132 from the first variant and 77 from the second and renumbered them into the classes 17^10-11 and 17^11-12. Their service with the Bundesbahn ended in 1954, with the Reichsbahn only in 1964. In the GDR, two of the locomotives were converted to pulverized coal firing as a test.