The R.370 group steam locomotive was a three-axle (locotender), coal-fueled locomotive that the State Railways built for service on Sicily's narrow-gauge lines with rack-and-pinion routes.Locomotives of the R.370 group were designed and built beginning in 1909 in anticipation of the coming into operation of Sicily's narrow-gauge railways serving the sulfur mining basins of the provinces of Enna, Caltanissetta and Palermo, which were then very important from the mining and economic point of view.
Their first use was in conducting convoys for miners and minerals from the sulfur basins of Lercara, Cianciana, Grottacalda and Floristella. They were used mainly on the lines:
Dittaino-Piazza Armerina-Caltagirone
Dittaino-Assoro-Leonforte
Agrigento-Naro-Licata railway
Lercara-Filaga-Magazzolo railway
Filaga-Palazzo Adriano railway
48 locomtives of this type were built from 1911 by Costruzione Mecchanice di Saronno, the gauge is 950 mm, with Strub cogwheel system.
