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
Baldwin Locomotive Works emerged from bankruptcy in 1938 it underwent a drastic change in management. The new management revived their development efforts with diesel power but the company was already too far behind. In 1939 Baldwin offered its first standard line of diesel locomotives, all designed for yard service. By this time, GM-EMC was already ramping up production of diesel passenger locomotives and developing its first diesel road freight locomotive. As the 1930s drew to a close, Baldwin's coal-country customers such as Pennsylvania Railroad, Chesapeake and Ohio, and Norfolk and Western were more reluctant than other operators to embrace diesel technology, which could