FS Class 625

FS Class 625
Locomotive 625.179
Type and origin Power type Steam Builder Gio. Ansaldo & C., Costruzioni Meccaniche di Saronno, Berliner Maschinenbau Build date 1914–1923 Total produced 188 Number rebuilt 153
Specifications Configuration: ​  • UIC 1′C h2 Gauge 1,435 mm (4 ft 8 1⁄2 in) standard gauge Leading dia. 840 mm (33.07 in) Driver dia. 1,510 mm (59.45 in) Length 9.66 m (31 ft 8 3⁄8 in) Axle load 14.4 tonnes (14.2 long tons; 15.9 short tons) Loco weight 53.9 tonnes (53.0 long tons; 59.4 short tons) Tender weight 31.9 tonnes (31.4 long tons; 35.2 short tons) Fuel type Coal Fuel capacity 6,000 kg (13,000 lb) Water cap 12,000 L (2,600 imp gal; 3,200 US gal) Firebox:  • Firegrate area 2.42 m2 (26.0 sq ft) Boiler pressure 12 kgf/cm2 (1.18 MPa; 171 psi) Heating surface 108.5 m2 (1,168 sq ft) Superheater: ​  • Heating area 33.5 m2 (361 sq ft) Cylinders Two, inside Cylinder size 490 mm × 700 mm (19.29 in × 27.56 in) Valve gear Walschaerts, Caprotti
Performance figures Maximum speed 80 km/h (50 mph) Power output 800 CV (590 kW; 790 hp) Tractive effort 10,200 kgf (100 kN; 22,500 lbf)

The Ferrovie dello Stato (FS, Italian State Railways) Class 625 (Italian: Gruppo 625) is a class of 2-6-0 'mogul' steam locomotives in Italy. The class is commonly known by the nickname Signorine (Italian for 'young ladies', also shared with the similar Class 640 locomotives), or Signorina in the singular, because of their perceived grace and beauty compared to other locomotives.

The Class 625 was the superheated and simple expansion version of the pre-existing mixed traffic Class 600 design; following with the success of the Class 640 (itself a superheated and simple-expansion version of the older Class 630 engines), previous designs were altered accordingly and 108 of the class were built from various companies in Italy between 1910 and 1914, and another 80 again between 1922 and 1923, of which the last 25 by Berliner Maschinenbau; the gap in the production run was caused by the events of World War I.

From 1929 onwards the existing 188 class 625 locomotives were supplemented by a further 153 locomotives rebuilt from older FS Class 600 engines; those, that could be distinguished from the Class 625 only from their being compound and non-superheated locomotives, had been constructed between 1904 and 1910 by Gio. Ansaldo & C., Costruzioni Meccaniche di Saronno, and Henschel & Son. A total of 153 class 600 engines were superheated, fitted with Caprotti valve gear and reclassified as class 625 machines between 1929 and 1933. Their class number changed from 600 to 625; they retained the sequential numbering from their original classification, but with the initial number altered to a 3. Thus the original 600 008 became 625 308, for example. After 1933 the remaining unrebuilt 95 class 600 engines were gradually scrapped.

The locomotives were designed for mixed-traffic operation (use on both passenger and freight services) and were designed to operate on steep gradients. The first examples of the class entered service upon completion in 1910, and the final operational examples were withdrawn from mainline service in 1976. A number of locomotives in the class were retained in working condition as part of Italian Railways' policy of keeping steam locomotives in reserve, well into the era of internal combustion and electric motive power. The final withdrawal from the reserve fleet was locomotive 625 100 in 1998.