The electric multiple unit Sm1 is a class of commuter train equipment that was in active use by VR from 1969–2016. Fifty Sm1 units were built between 1968 and 1973 at Valmet airplane factory in Tampere. They were put into use on the first electrified Finnish railway line between Helsinki and Kirkkonummi on January 26, 1969 with five units in operation. All Sm1s were thoroughly renovated between 1994 and 2000. Commercial service ended in April 2016.
Technical information
Each Sm1 unit consists of two cars: the Sm1 is the motored car of the multiple unit, while the other car, the driving trailer, is a part of the Eio class. There is a driver's cabin at either end of the unit, which enables the train to be driven in both directions without turning it around. This is a major advantage compared to locomotive-pulled trains in commuter traffic. The two-car unit has 191 seats combined, including fourteen foldable seats.
Six Sm1 units can be coupled together in total, but the length of the commuter train platforms limits the maximum length to five in commercial traffic. Six unit trains can be seen in depot traffic between Helsinki Central Station and Ilmala depot. The units use Scharfenberg couplers.
The maximum speed of the Sm1 is 120 km/h. The electric systems were developed and built by Strömberg at their plant in Pitäjänmäki, Helsinki.