 In 1925 the Deutsche Reichsbahn grouped these engines into their DRG Class 99.51–60.As a result of the constantly rising traffic on the Saxon narrow gauge railways towards the end of the 19th century, the power of the existing Saxon I K and III K soon proved insufficient.So the Sächsische Maschinenfabrik developed an engine with eight coupled wheels and which had a larger boiler and adhesive weight.