In 2010, the CFBS bought these two small second-hand diesel shunters from the Rhaetian Railways (RhB) in South-Eastern Switzerland.
Units Tm 2/2 N° 15 and 21 were part of a series of 12 shunters ordered by the RhB for service work and shunting goods wagons in the stations of the Grisons canton.

N°15 was built in 1957 and N° 21 in 1965 by the Raco company in Landquart. Easy to drive, these shunters are of a simple design, with a chain transmission, a 4-speed gearbox and a counterweight handbrake. They feature a small open platform at the front, for carrying tools or parcels. In 1989, they were fitted with Cummins 4BT3.9 diesel engines.

They are affectionately known as “Pilous”.
On the CFBS, they are assigned to shunting duties such as moving cold engines around the works, or carriages and wagons in a station or in the works. They can also be used for short work trains or other types of lightweight line services, provided no passengers are carried.