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-Zarlatti locomotive A six-cylinder, two-stroke, diesel engine built by Fiat-San Giorgio was installed. This engine produced 325 hp at 450 rpm and drove a rotary compressor, built by a Swiss company in Winterthur, which delivered compressed air at 8 bar pressure. A small naphtha-fired boiler with a heating surface of 52 square metres was also installed for the production of steam. Cooling water from the engine and compressor was fed into the boiler at about 70°C. For cold starting, the boiler was used to preheat the diesel engine. When the locomotive started from rest, the original steam cylinders were fed with steam