Diesel locomotive Diesel–hydraulic locomotives have a smaller market share than those with diesel electric transmission - the main worldwide user of main-line hydraulic transmissions was the Federal Republic of Germany, with designs including the 1950s DB class V 200, and the 1960 and 1970s DB Class V 160 family. British Rail introduced a number of diesel hydraulic designs during it 1955 Modernisation Plan, initially license built versions of German designs (see ). In Spain RENFE used high power to weight ratio twin engined German designs to haul high speed trains from the 1960s to 1990s. (see RENFE Classes 340, 350, 352, 353,
Diesel locomotive FT demonstrator freight locomotive set, the stage was set for dieselization of American railroads. In 1941 ALCO-GE introduced the RS-1 road-switcher that occupied its own market niche while EMD's F series locomotives were sought for mainline freight service. The US entry into World War II slowed conversion to diesel; the War Production Board put a halt to building new passenger equipment and gave naval uses priority for diesel engine production. During the petroleum crisis of 1942-43, coal-fired steam had the advantage of not using fuel that was in critically short supply. EMD was later allowed to increase production of its