The Prussian T 9 was a class of German steam locomotive which included several types of tank engine, all with six coupled wheels and two carrying wheels operated by the Prussian state railways.
Read more about Prussian T 9: T 9.1, T 9 - Elberfeld Variant, T 9 - Langenschwalbach Variant, T 9 - Upper Hessian Railway, T 9.2, T 9.3, See Also, Sources