Between 1896 and 1902, the Jura-Simplon Railway got 75 2-6-0 locomotives for mixed traffic which had been built by the SLM. They were three-cylinder compounds where the single inside high-pressure cylinder drove the first driving axle and the two outside low-pressure cylinders drove the second driving axle. With a top speed of 75 km/h they also had to haul express trains in the mountains, but this task was taken over by the A 3/5 when this was introduced in 1902. After the founding of the SBB, 72 more were built between 1902 and 1907 which were nearly identical.

As early as in 1905, superheater technology was introduced with a modified design that had two cylinders with simple expansion and a boiler pressure that had been reduced from 14 to 12 bars. Most of the saturated compounds were retired starting in 1923 when electrification in Switzerland had been progressed. Only five which had been part of the war reserve were sold to the Netherlands in 1945 and became NS series 3000. Only a few of the superheated locomotives had been retired in the thirties, most followed in the fourties and fifties. The last one was No. 1367, which was retired in 1964 and is the only one that was preserved and still operational today.