Statens Jarnvagar 4-6-2 Locomotives in Sweden

Class F (Locobase 2477)

Data from "Re-introduction of Express Compound Engines on the Swedish State Railways", Railway Engineer, Volume 35, No 11 ( November 1914), pp.341- ; and "Compound Express Locomotive, Swedish State Rys.", Locomotive Magazine, Volume 21 (15 October 1915), pp. 222-225.

This engine class led a double life. Designed by Carl Flodin for the Stockholm-Gothenburg and Stockholm-Malmo express lines, these soundly designed locomotives were the first in the world to use roller bearings on the axles. Interestingly, the Brimalm model site's account of the class -- [] (visited 18 April 2003) -- says the roller bearings on the leading bogie of the lead locomotive and the tender trucks did not work out well and were replaced with axle journals.

A compounding system similar in concept to that of Samuel Vauclain used one valve to serve both cylinders on a side, with the HP cylinder.s front and LP cylinder's back thus very close to one another and thus minimizing the steam passage length between them.. The RE report claimed that setting the four cylinders side-by-side and driving on a single balanced axle (the middle set of drivers) reduced complication and weight in the Swedish arrangement. This especially benefited the outside LP cylinders, which could be made lighter and require less balancing. (See Locobase 1552 for an extended analysis of proper compounding design published a few months later in Railway Engineer that held the F class up as the proper way design such a locomotive.)

The requirement laid down for these engines was to haul 500 ton trains on the level at 100 kph (62 mph) and 60 kph (37 mph) when climbing a 1% grade. Maximum speed was claimed to be 127 kph (80 mph).

After decades of successful operation in Sweden, electrification made these engines redundant and they were sold to Denmark as Class E; see Locobase 2478