2-6-2 fourcylinder compound express train steamlocomotive 685 # 600 exhibited in the Museo Nazionale Scienza e Tecnologia Leonardo da Vinci in Milan. The steam locomotives of the FS 685 class of the Ferrovie dello Stato Italiane (FS) were tender locomotives for light express trains
with a four-cylinder engine. The 1'C1' axle arrangement used is referred to as Prairie. 391 locomotives were built in five series and various. It was the most frequently built Italian express steam locomotive. Just a few years after the FS 680 series of wet steam locomotives with four-cylinder compound engines entered service, a four-cylinder superheated steam locomotive with single-stage steam expansion, i.e. without compound action, was built using their design features and delivered from 1912. Breda delivered the first two series as FS 68501 to FS 68566 and FS 68567 to FS 68806, the later FS 685.001-066 and FS 685.067-106. In 1921 and 1922, Breda delivered the third series as FS 685. In 1927, the fourth series, consisting of FS 685.222-231 from Officine Meccaniche Italiane from Reggio Emilia (Reggiane) and FS 685.232-241 from Officine Meccaniche Napoli, entered service. The fifth series is the variant with Caprotti valve control, delivered in 1926 and 1927 by O.M. Milan and Saronno in 30 units, initially built as a separate series FS 686 with the road numbers FS 686.005-034. In 1930, they were incorporated into the 685 series as FS 685.955-984. Construction
The standardized design followed simple construction principles. Many components were taken over from the previous FS 680 version. A composite running gear was dispensed with. The operating pressure of the boiler, which was of a similar type to that of the 680 series, was designed to be low and produced an hourly steam output of 10,200 kg. Nevertheless, the increase in power to 1,250 hp compared to the previous version was remarkable. The supporting structure was a rigid frame, which was mounted on the three large drive wheels. The steering frame - consisting of the first and second axles - corresponded to the Italian Zara design, a variant of the German Krauss-Helmholtz steering frame. The front running axle was 60 mm laterally displaceable, the rear 20 mm. The machines had steam heating and air brakes. From the third series onwards, a longer boiler was installed and the unladen weight of the locomotive increased from 70.8 tons to 72.1 tons. Operation: Until the 1960s, the locomotives made an important contribution to express train services throughout Italy. They seemed to be particularly popular and suitable for the lowland routes in central and northern Italy, for example on the routes from Milan to Rome or Venice, but also on the Rome-Cassino-Naples line. From the fall of 1935, they were also used from the Catania and Palermo depots on the lines from Messina to Syracuse and Palermo. With the completion of the electrification of the last main lines in the Po Valley, their area of operation was downgraded to services on the secondary lines. Here they remained until the completion of dieselization in the early 1970s. The last locomotives were FS 685.196, assigned to the Udine depot, which was maintained until 1974 for a daily passenger train on the Udine-Cervignano line, and FS 685.222, which completed its last run on January 20, 1975 in front of a freight train on the line from Cremona to Codogno.
The splinter class FS 683 was transferred to Udine in May 1959. Three of the four locomotives were then transferred to Bari for a short time until all four were in service at the Bari, Foggia and Udine depots until 1962, when they were decommissioned. Text from Wikipedia.
