Around 1910, the FS also realized that, thanks to superheater technology, compound engines could be dispensed with. Therefore the Pacifics of the class 690 II with four cylinders were commissioned. For the first time on a simple expansion locomotive in Italy, two adjacent cylinders used a common piston valve. The locomotives were designed for an axle load of 18 tonnes, but were ultimately manufactured with an axle load of only 17.1 tonnes for a better road availability.

The first nine were built with the driver's position on the right, the remaining 24 had it on the left. The firebox was partly located between the drivers and was therefore trapezoidal and narrow at the front. Since the grate had too small an area, the output was only 1,400 hp. Together with the axle load, which was still too high for most lines, no further class 690 locomotives were built. This led to a rebuild to class 691 at the end of the twenties and the class 695 to be developed as a successor.

The Grupo 740 of the Italian State Railway was a freight locomotive with a 2-8-0 wheel arrangement, which achieved the highest number of all steam locomotives on this railway. It was based on the Grupo 730, but unlike it had no compound engine and was superheated. From 1911 the locomotives were supplied by Breda and Ansaldo and after the First World War Henschel supplied a larger number as reparation, which had three-axle tenders instead of four. A total 470 were made by 1923.

Like the 730, they could be used freely due to their low axle load and could also pull passenger trains if necessary. Officially they were approved for a speed of 65 km/h, but could also reach up to 80 km/h. Seven were rebuilt to Caprotti valve gear, which was successful, but due to more difficult maintenance led to these locomotives being retired in the 1960s.

The rebuilds to Franco Crosti boilers, which was carried out on 175 locomotives, was more successful. These were divided into Grupo 743, which had a preheater on both sides of the boiler, and Grupo 741 with only one preheater under the boiler, which delivered the same power. Both the rebuilt and non-rebuilt ones survived until the end of the steam age on the FS in the seventies. Some were even kept as reserves until the early nineties. A total of 49 were preserved, three of which are still operational.

When in the early 1920s, the existing six-coupled express locomotives of the FS could no longer provide sufficient adhesive weight on hilly routes, the FS was one of the first railway companies in Europe to develop an eight-coupled express locomotive. This was the only way to comply with the maximum axle load of 17 tonnes that applied on hilly routes such as those in the Rome and Florence area. It was based on the 2-6-2 locomotive of the class 680 and added another coupled axle. 

While up to this point engines based on the Plancher system were preferred for four-cylinder compound locomotives in Italy, here the system according to von Borries, which was also used in Germany, was used. There were thus two inside high-pressure cylinders and two outside low-pressure cylinders, all of which acted on the third coupled axle. In order to create space for the connecting rods of the inner cylinders, the cylinders were arranged somewhat higher and inclined, and the second coupling axle was slightly cranked.

In contrast to the bar frame, which was very popular with express locomotives on the European mainland at the time, a plate frame with a thickness of 30 mm was used here. The leading axle with a lateral play of 94 mm was combined with the first coupled axle to form a Zara bogie and gave it a play of 20 mm. Due to the large grate area, the trailing axle was further away from the last coupled axle and therefore had a lateral play of 140 mm.

Schematic drawing with dimensions

Locomotive Magazine, July 1921

The production initially consisted of 40 engines that were supplied by Breda and had Heusinger valve gear. Another 20 pieces came from Ansaldo and received a Caprotti valve gear. These were initially designated class 477 and redesignated 746.100 in 1929. After their original routes were electrified, the locomotives were re-stationed once each in 1935 and 1937. They eventually landed in Sicily and were retired by 1967. Today only the 746.038 survives and is located in Milan, where it was once made.