Diesel locomotive were classified as DET 1 and DET 2 (). Due to shortage of petrol products during World War I, they remained unused for regular service in Germany. In 1922, they were sold to Swiss Compagnie du Chemin de fer Régional du Val-de-Travers (), where they were used in regular service up to the electrification of the line in 1944. Afterwards, the company kept them in service as boosters till 1965. Fiat claims a first Italian diesel–electric locomotive built in 1922, but little detail is available. A Fiat-TIBB diesel–locomotive "A", of 440CV, is reported to have entered service on the Ferrovie
Diesel-Zarlatti locomotive alone, but when running they were powered by a mixture of steam and compressed air. The steam was needed to prevent the cylinders icing up, because compressed air cools when it expands. Diesel-Zarlatti locomotive The Diesel-Zarlatti locomotive was a prototype railway locomotive, built in Italy in 1929, which adopted a hybrid diesel-steam transmission system. In the 1920s, there was a search for alternatives to the steam locomotive for railway traction, to reduce cost and improve efficiency. The main alternatives were railway electrification or the use of an internal combustion engine, such as the diesel engine. A disadvantage of the internal