FS Class 680

The Class 680 was an Italian four-cylinder compound 2-6-2 Prairie express steam locomotive built for the Italian State Railways from 1907. It was designed as a standardised successor to the fast Class 500 engines of the Rete Adriatica and used the same Plancher compound layout, in which the two high-pressure cylinders sat on one side of the smokebox and the two low-pressure cylinders on the other, each pair served by a single piston valve. Designed for 75 miles per hour in express service with trains of about 400 tonnes, the class took over the principal services between Rome, Naples and Florence, and one engine reached 118 km/h on a trial run. Breda delivered 91 of the engines, Ansaldo 40 and Berliner Maschinenbau 20. The layout left the engines somewhat unbalanced at speed, and their success was brief, because the simple-expansion superheated Class 685 entered service in 1912 and made the 680 obsolete. Many of the 680s were later rebuilt with superheaters.