The

Ferrovie dello Stato Ferrovie dello Stato Italiane S.p.A. ( "Italian Railways of the State"; previously only Ferrovie dello Stato, hence the abbreviation FS) is Italy's national state-owned railway holding company that manages transport, infrastructure, real estat ...

(FS; Italian State Railways) Class 640 (Italian: ''Gruppo 640)'' is a class of

2-6-0 Under the Whyte notation for the classification of steam locomotives, represents the wheel arrangement of two leading wheels on one axle, usually in a leading truck, six powered and coupled driving wheels on three axles and no trailing wheels. ...

'Mogul' steam locomotives in Italy. Commonly nicknamed "''Signorine''" (Italian: 'young ladies'), a nickname shared with the similar Class 625, these locomotives were the first

superheated A superheater is a device used to convert saturated steam or wet steam into superheated steam or dry steam. Superheated steam is used in steam turbines for electricity generation, steam engines, and in processes such as steam reforming. There are ...

steam locomotives in Italy.

Design and construction

When the FS were created in 1905, Chief Mechanical Engineer

Giuseppe Zara Giuseppe Zara (Fermo, 1856 – Sanremo, 1915) was an Italian inventor. He was a member of the Società Italiana per le Strade Ferrate Meridionali, and the director of Ferrovie dello Stato from 1905. He graduated at the Technical Institute of Fermo ...

undertook a process to design a standard range of locomotives; one of these was the Class 630, a light express engine which, together with the other designs, shared the features of being

compound locomotive A compound locomotive is a steam locomotive which is powered by a compound engine, a type of steam engine where steam is expanded in two or more stages. The locomotive was only one application of compounding. Two and three stages were used in shi ...

s. However, with the diffusion in

Germany Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwe ...

(then in close ties with Italy because of the

Triple Alliance Triple Alliance may refer to: * Aztec Triple Alliance (1428–1521), Tenochtitlan, Texcoco, and Tlacopan and in central Mexico * Triple Alliance (1596), England, France, and the Dutch Republic to counter Spain * Triple Alliance (1668), England, the ...

) 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 the Italian bogie and the peculiar inside-cylinders/outside valve chests and valve gear) was taken. 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 firm Schwartzkopff (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

Operations

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 powerful Class 680 and Class 685

2-6-2 Under the Whyte notation for the classification of steam locomotives, represents the wheel arrangement of two leading wheels, six coupled driving wheels and two trailing wheels. This arrangement is commonly called a Prairie. Overview The major ...

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.

Modifications

Between 1929 and 1931 15 Class 630 locomotives were rebuilt with superheater, simple expansion and

Caprotti valve gear The Caprotti valve gear is a type of steam engine valve gear invented in the early 1920s by Italian architect and engineer Arturo Caprotti. It uses camshafts and poppet valves rather than the piston valves used in other valve gear. While basi ...

; their running numbers were retained with the addition of 300, making them form the 640.3XX subclass.

Preservation

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.

References

* * {{FS locos 640-2 2-6-0 locomotives Berliner locomotives Breda locomotives Gio. Ansaldo & C. locomotives Costruzioni Meccaniche di Saronno locomotives Railway locomotives introduced in 1907 Standard gauge locomotives of Italy 1′C h2 locomotives Passenger locomotives