Diesel locomotive set, and went into series production with other streamlined car sets in Germany starting in 1935. In the USA, diesel-electric propulsion was brought to high speed mainline passenger service in late 1934, largely through the research and development efforts of General Motors from 1930–34 and advances in lightweight carbody design by the Budd Company. The economic recovery from the Second World War saw the widespread adoption of diesel locomotives in many countries. They offered greater flexibility and performance than steam locomotives, as well as substantially lower operating and maintenance costs. Diesel–hydraulic transmissions were intrdouced in the 1950s, but from the
TU7 diesel locomotive the TU7 - TU7A () diesel locomotive, is a series of diesel locomotives currently used on the Vietnamese railway network. With 77 locomotives D4H in service throughout the country as of 2005, it is the most common type of locomotive in use in Vietnam. The series was originally procured from the Soviet Union after the Vietnam War. TU7 diesel locomotive TU7 (ТУ7) - Soviet, later Russian diesel locomotive for gauge – . The TU7 () was developed in 1971-1972 at the Kambarka Engineering Works to replace the aging locomotive classes TU4 () and TU2 (ТУ2). There were 3,361 locomotives constructed,