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.jpg) FS locomotive 640.143 in 2012 | |||||||||||||||||||||||||||||||||||||||||||||||
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TheFerrovie dello Stato (FS; Italian State Railways)Class 640 (Italian:Gruppo 640) is a class of2-6-0 'Mogul' steam locomotives in Italy. Commonly nicknamed "Signorine" (Italian: 'young ladies'), a nickname shared with the similarClass 625, these locomotives were the firstsuperheated steam locomotives in Italy.[1]
When the FS were created in 1905, Chief Mechanical EngineerGiuseppe Zara undertook a process to design a standard range of locomotives; one of these was theClass 630, a light express engine which, together with the other designs, shared the features of beingcompound locomotives. However, with the diffusion inGermany (then in close ties with Italy because of theTriple Alliance) of the Schmidt superheater, a decision to build there a batch of 24 non-compound and superheated versions of the Class 630 (keeping all the other features, including theItalian bogie and the peculiar inside-cylinders/outside valve chests and valve gear) was taken.[2] Results were highly successful, and subsequently almost all steam locomotives in Italy would be built with simple expansion and superheating.
The first locomotives were built by the German firmSchwartzkopff (as the Italian industry lacked experience with the superheating technology), with other Italian firms building the rest, for a total of 169; four more Class 640 were added in 1951 when the railway company for which they had been built for (Strade Ferrate di Biella) was incorporated in the FS.
All the Class 640 were fitted with a unique three-axle tender with a water capacity of 15,000 L (4,000 US gal)
Originally pulling the principal express trains on the Italian mainlines, after a few years the Class 640 locomotives were replaced in these services by the more powerfulClass 680 andClass 6852-6-2 locomotives; they were then assigned to pulling passenger trains on secondary lines with level ground. They enjoyed a very long career, surviving up to the end of regular Italian steam services in the 1970s.[1]
Between 1929 and 1931, fifteen Class 630 locomotives were rebuilt with superheaters, simple expansion andCaprotti valve gears. Their running numbers had 300 added to them, making them form the640.3XX subclass.[1]
Sixteen Class 640 locomotives survive into preservation; of these, two (the 143 and 091) are currently operational and available for heritage trains, while others are being restored.[3]
