Mediterraneo / FS 4-6-0 Locomotives in Italy

Class Allessandro Volta (Locobase 20993)

Data from "Italian Locomotive at the Paris Exhibition: The Exhibition of the Mediterranean Railway Company", Engineering, Volume 70 (14 September 1900), pp. 336, 346; and "Locomotiva FS 660" on Wikipedia at [], last accessed 13 March 2022.

This was the showpiece of the four-coupled express compound design that would be produced as the Gruppo 660 (Locobase 2705). A von Borries cross-compound "with certain modifications," it used a mixture of a double piston valve on the HP cylinder and a balanced slide valve on the LP cylinder. It also used an automatic starting valve for increased tractive effort.

Its appearance at the 1900 Paris Universal Exposition garnered full coverage in Engineering, but it was the only example built by Ansaldo. Wikipedia noted that its boiler pressure set lower than any other 660s.

Class Gruppo 660 (Locobase 2705)

Data from the table presented on pages 370, 372 of the Groupe VI. - GTnie civil. - Moyens de transport. DeuxiFme partie. Classes 32 (Tome I), part of the series of Rapports du Jury Internationale of the Exposition Unverselle Internationale de 1900 Paris Exposition, hosted on the website of Le Conservatoire numTrique des Arts & MTtiers ([], Accessed 21 August 2005).

Additional data from diagram published on DUEGI EDITRICE's TuttoTreno website [], a modelling site with a great deal of data. (visited 11 July 2004). It is the Gruppo 660 diagram that supports the identification of this Mediterraneo locomotive. The combination of wheel arrangement, building years, and driver diameter are found only in this class.

These two-cylinder compounds were designed to meet a requirement to pull 220 tons on the flat at 58 mph. between Rome and Pisa.