When the Pilatus railway was opened in 1887, it was the steepest rack railway in the world with 48 percent and it still holds this title today. For this the SLM had built nine steam rack railcars with inclined cab and passenger compartments to match the grade of the track. The boiler was mounted laterally on the valley side.
In 1900 and 1909, numbers 10 and 11 were built. 11 had a top speed of 4.4 instead of 3.6 km/h. Later all were superheated and got a revised suspension. Their service ended in 1937 when the Pilatus railway was electrified. No. 9 was used as a catenary-independent service vehicle until 1982. Today it is on display in Lucerne, while 10 can be found in Munich. 