The D IX steam locomotive was manufactured by the firm of Maffei between 1888 and 1899 for the Royal Bavarian State Railways (Königlich Bayerische Staatsbahn).
They were used on the route from Reichenhall via Freilassing to Salzburg.
After one engine had been successfully employed on the route to Berchtesgaden, the vehicles were also deployed on the suburban lines of Augsburg, Munich and Nuremberg.
Not until 1896 were minor changes made to the heating areas, the weights and the coal and water capacities.
The rigid mounting of the driving and carrying wheels and the location of the cylinder just in front of the carrying wheel did not prove a success.