(Compiled by Christer Brimalm)
The beginning of the twentieth century was a period of accelerating technical development on the railways. Ever heavier trains and higher speeds put growing demands on the locomotive designers. In 1906 the highest permissible speed on the SJ hade been raised to 90 kph (55 mph). During the same year the Class A Atlantic engines had been introduced. These fast and freerunning engines were little short of a sensation when they came, but already in a few years it was evident that the development was running ahead of them. With four coupled wheels they were too weak for heavy express trains. The Class B, which was introduced in 1910, was more sure-footed when starting and had a somewhat higher power, but it was soon evident that this engine class too would soon prove unsatisfactory for the most demanding express train duties.
When, in 1912, the SJ decided on procuring a new class of express engines, it was considered essential that the new engines be powerful enough to fullfil all traffic requirements for a long time to come. All the the design work was done by the staff of the SJ mechanical design bureau, headed by the chief mechanical engineer, Carl Flodin. He had also taken part in the designing of the classes A and B and it is not without reason that he has been named "Father of the Modern Swedish Steam Locomotive". For the new engine class , the wheel arrangement 4-6-2 (Pacific) was chosen, for the first and only time in Swedish locomotive history. Internationally, however, this is very common wheel arrangement for express locomotives.
Mechanically the Class F was designed as a four cylinder compound engine with two inside and two outside cylinders, all driving on to the middle coupled axle. At this time the SJ was much influenced by German railway technology. The most modern contemporary German express locomotives, i.e. Baden State Railways Class IV f from 1907, The Bavarian S 3/6 from 1908, The Würtemberg Class C and the Prussian S 101, were all 4 cylinder compounds, a fact which can scarcely have escaped making an impression on the SJ staff. Three of the German engines were Pacifics. The Würtemberg Class C and the Swedish Class F have a strikingly similar appearance.
NOHAB in Trollhättan received an order for one prototype example of the new class, nr 1200, which was delivered in March 1914 and shown at the Baltic Exhibition in Malmö during the summer. Later the same year a series of test runs were made between Stockholm Tomteboda and Uppsala during which careful measurements were made. With 400 ton trains speeds up to 120 kph (75 mph) were reached. One trip was done in 42 minutes, corresponding to an average speed of 90 kph (55 mph). The measurements showed that the highest energy efficiency and highest power was obtained at speeds around 100 kph (62 mph). The running characteristics were excellent even at higher speeds.
One innovation, which proved less successful, was the ball bearings fitted to the axles of the leading bogie as well as the tender axles of F 1200. These did not withstand the load and were later replaced by ordinary axle journals. The following examples of the class were delivered with conventional axle journals from the beginning.
An order for 10 more engines (Numbers 1201-1209 and 1271) was now placed with NOHAB. They were delivered in 1915-16 and put in traffic on the Stockholm-Malmö trunk line.
In 1918 F 1200 was involved in the severe accident at Getå when passenger train 422 was derailed and hurled down a high embankment built against the mountainside along the sea. 41 people were killed in this disaster, which is the worst in Swedish railway history. The engine, however, could be repared, and is still in existence, preserved at the Railway museum in Gävle.
After electrification of the Stockholm-Malmö trunk line the Class F engines were moved to the Göteborg-Malmö line on the West Coast. When this trunk line too had been electrified in 1937 the SJ had difficulty finding a suitable duty for these locomotives. Therefore they were sold the same year for a very attractive price to the Danish State Railways, DSB. In Denmark the engines were designated Class E and received the numbers 964-974. They were rebuilt with Danish cabs and the drivers position was moved from the left to the right hand side. The highest permissible speed was raised to 110 kph (68 mph) in Denmark, a more suitable speed for a Pacific engine than the modest 90 kph permitted on Swedish lines due to the standard of the tracks and the somewhat conservative technical norms of the SJ. On the whole the locomotives were better suited to the duties assigned to them in Denmark and they were considerably higher appreciated there.
One proof of this is the fact that the DSB, when new express engines were needed, chose to order more of the same type. No less than 25 examples (E 975-999) were produced by Frichs in Århus 1942-50. They were built after the main drawings from NOHAB, but differed in certain details from the earlier engines. Among other things they had a cab totally built of steel, a second boiler dome and a welded tender.
During the 1960ies the Class E was gradually replaced by diesel locomotives. The last regular duties were local passenger trains 2205 and 254 Copenhagen-Kalundborg and return in 1967-68. Well into the 1970ies Class E engines were still on the regular locomotive roster of the DSB and could be used as spare engines and on special occasions. In 1972 numbers 978 and 994 had the honour of hauling a special train which carried the remains of the deceased king Fredrik IX from Copenhagen to Roskilde. The king, who had been a railway enthusiast, had himself requested to be carried to his last rest by steam train, and it was therefore decided to honour his memory in this manner.
Of the 36 Class F/E engines built, 7 examples remain in existence today. F 1200 was handed back to the SJ in 1963 in exchange for a Class R goods engine. After restoration (as far as possible) to its original Swedish state, it is preserved at the Swedish Railway Museum in Gävle in servicable condition. Of the Swedish-built locomotives, one more (E 966, ex F 1202) has been preserved in Denmark. This engine has recently been sold to the Swedish Railway Museum, which plans to use it for enthusiasts specials in the future and let the unique F 1200 rest secure at the museum. Five Danish-built engines are preserved in Denmark, namely numbers 978, 987, 991, 993 and 996. Nr 999, the last steam locomotive built for the DSB, was sadly destroyed in a fire in the Struer engine shed in 1981 and had to be cut up. E 991 is servicable and may be seen under steam from time to time.
Dimensions of the Swedish-built engines:
Cylinder diameter 420/630 mm
Cylinder stroke 660 mm
Driving wheel diameter 1880 mm
Locomotive weight 87,8 tons
Tender weight 55,0 tons
Adhesion weight 48,0 tons
Grate area 3,60 m²
Heating area 189,3 m²
Superheater area 63,0 m²
Boiler pressure 13 kp/cm²
Water capacity 25 m³
Coal capacity 6,5 tons
Lenght over buffers 21,3 m
When the locomotives were new they were allocated to the Stockholm (Hagalund) and Malmö engine sheds.
In 1931 five engines (1200, 1201, 1202, 1203 and 1208) were allocated to Norrköping shed and six engines (1204, 1205, 1206, 1207, 1209 and 1271) to Nässjö shed.