The first successful diesel engines used diesel–electric transmissions, and by 1925 a small number of diesel locomotives of were in service in the United States. In 1930, Armstrong Whitworth of the United Kingdom delivered two locomotives using Sulzer-designed engines to Buenos Aires Great Southern Railway of Argentina. In 1933, diesel–electric technology developed by Maybach was used to propel the DRG Class SVT 877, a high-speed intercity two-car set, and went into series production with other streamlined car sets in Germany starting in 1935. In the United States, diesel–electric propulsion was brought to high-speed mainline passenger service in late 1934, largely through the research and development efforts of General Motors dating back to the late 1920s and advances in lightweight car body design by the Budd Company.