SJ Steam Locomotives F-class

The Story of the SJ F-class Steam Locomotives

In the early 1900s, the Swedish State Railways (SJ) faced a challenge: their A-class locomotives were no longer powerful enough for the growing demands of express train service. To solve this, SJ introduced a new generation of steam locomotives—bigger, stronger, and faster than anything they had used before.

Between 1914 and 1916, eleven locomotives of the new F-class were delivered, built by Nydquist & Holm (NOHAB. These powerful engines featured four-cylinder compound technology, superheaters, Walschaerts valve gear, and a 4-6-2 Pacific wheel configuration—a design rarely seen in Sweden. The construction likely took inspiration from the Württemberg C-type locomotives in Germany, sharing several design traits.

Initially, the F-class locomotives hauled heavy express trains between Stockholm and Malmö on the Södra Stambanan (Southern Main Line) and and later between Stockholm-Gothenburg. They were based in Hagalund and Malmö and later reassigned to depots in Norrköping and Nässjö. Over time, they also served on local passenger routes.

In 1918, the original paraffin lighting system was replaced with gas lighting (Dahlén system), and the front smokebox lamp was removed. By 1922, the brake system was upgraded from vacuum brakes to compressed air brakes (Kunze-Knorr system), improving safety and performance.

One locomotive, F 1200, was involved in the tragic Getå accident in 1918 but was repaired and returned to active service—a testament to the durability of these machines.

When SJ began electrifying its main lines in the 1930s, the F-class was gradually phased out. In 1933, after the electrification of the Southern Main Line, the locomotives were moved to the West Coast Line (Göteborg–Malmö). But as that line also transitioned to electric power by 1937, the entire fleet was sold to DSB (Danish State Railways), where they became known as E-class locomotives. Amazingly, some remained in service in Denmark until 1970.

Today, the SJ F 1200 remains a fascinating piece of Scandinavian railway history—representing a time when steam power ruled the rails and locomotive design was at its peak.

Danish e-class locomotive: