In 1916, Motala Workshop manufactured three units of Sweden's largest tank locomotives for service in heavy goods trains on the Uppsala-Gävle Railway. They were designated UGJ I 27-29 and were taken over by the Swedish State Railways (SJ) in 1933. In 1942, the locomotives were reclassified as SJ N2.

After sporadic use in various locations across Sweden, around 1960 the locomotives were decommissioned as reserve engines. Two locomotives were scrapped in 1970, and one is preserved in the vehicle collection at the Railway Museum in Gävle.

Length: 13.65 metres
Service weight: 88.2 tonnes
Material weight: 65.8 tonnes
Driving wheel diametre: 1.4 metres
Coal capacity: 4.1 tonnes
Water capacity: 10 cubic metres
Speed: 70 kilometres per hour
Steam pressure: 12 kilogrammes per square centimetre