TU7 diesel locomotive
TU7 (ТУ7) - Soviet, later Russian diesel locomotive for gauge – . History. 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, of which several hundred were exported to the countries of the socialist community and affiliated countries. The TU7 - TU7A () was designed to be used on any gauge from to . In 1986 the locomotive design was updated and designated type TU7A (). D4H. The D4H and 9 locomotives D4Hr for standard gauge , also known as 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.