FS Class 470

FS Class 470
FS locomotive 470.092 as preserved
Type and origin Power type Steam Builder Maffei (64), Officine Meccaniche (52), Ernesto Breda (10), Officine Meccaniche e Navali di Napoli (17) Build date 1907–1911 Total produced 143
Specifications Configuration: ​  • Whyte 0-10-0  • UIC E n4v Gauge 1,435 mm (4 ft 8 1⁄2 in) Driver dia. 1,370 mm (53.94 in) Length 12,475 mm (40 ft 11.1 in) Axle load 15.1 tonnes (14.9 long tons; 16.6 short tons) Loco weight 74.8 tonnes (73.6 long tons; 82.5 short tons) Tender weight 27.6 tonnes (27.2 long tons; 30.4 short tons) Fuel type Coal Fuel capacity 5,600 kg (12,300 lb) Water cap 13,000 litres (2,860 imp gal; 3,430 US gal) Firebox:  • Firegrate area 3.5 m2 (38 sq ft) Boiler pressure 16 kg/cm2 (1.57 MPa; 228 psi) Heating surface 212.57 m2 (2,288.1 sq ft) Cylinders Four (compound) High-pressure cylinder 375 mm × 650 mm (14.76 in × 25.59 in) Low-pressure cylinder 610 mm × 650 mm (24.02 in × 25.59 in) Valve gear Walschaerts
Performance figures Maximum speed 50 km/h (31 mph) Power output 736 kW (987 hp) at 30 km/h (19 mph) Tractive effort 14,200 kgf (139 kN; 31,300 lbf)

The Ferrovie dello Stato Italiane (FS; Italian State Railways) Class 470 (Italian: Gruppo 470) is a 0-10-0 steam locomotive.

The Class 470 locomotive was one of twelve standard designs developed by the FS right after their institution, and was intended for heavy mountain work. The two extreme axles were given a lateral play of 40 millimetres (1.6 in) and the central wheels were without flanges, to allow the locomotive to deal even with sharp curves. The boiler was common with that of the FS Class 680, as was the four-cylinder compound Plancher engine, in which the two high pressure (HP) and the two low pressure (LP) cylinders were respectively grouped together, with each pair being served by a single piston valve via a crossed port arrangement.

The Class 470 was unusual in its appearance because the coal reserves were carried on board it, on the left side of the fully enclosed cab, while the water was carried by a separate tender; this has led some to define them "semi-tank locomotives".

The Class 470 was built between 1907 and 1911 by Maffei (64 locomotives, 1907–09), Officine Meccaniche (52, 1908–11), Ernesto Breda (10, 1909) and Officine Meccaniche e Navali di Napoli (17, 1909–12), for a total of 143 locomotives.

P. M. Kalla-Bishop suggested that the Midland Railway 0-10-0 "Lickey Banker", which shared with the Class 470 the wheelbase and the crossed port arrangement, may have been inspired by it, as a complete sets of drawings of the Italian locomotive were stored at Derby.

From 1918 until the 1930s, all but 14 of the Class 470 were rebuilt with a superheater and reclassified as the Class 471 (while keeping their old running numbers, e.g. the 470.018 became 471.018). From 1924 some of the rebuilt locomotives (24 in total) were also given enlarged HP cylinders of 400 mm (16 in) diameter, and were initially reclassified as Class 472; from 1930 however these were renumbered in the Class 471 as the sublass 471.2XX. In total, 105 Class 471 and 24 Class 472 locomotives were rebuilt.

109 of the rebuilt 471 and 472 locomotives were also altered from their original semi-tank condition to orthodox tender locomotives, being fitted tenders of the extinct FS Class 290, with a capacity of 6,000 kg (13,000 lb) of coal and 15,000 l (4,000 US gal) of water; later, tenders previously allocated to the FS Class 730, with a capacity of 20,000 l (5,300 US gal) of water, were also fitted to some locomotives.