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
Rigid-framed electric locomotive reluctant single prototype, built for comparison with the articulated 2′B+B1′ , which had themselves been a reaction to the poor performance of the 1912 1′D1′ . A rare example of the 2′D2′ layout was the unique British diesel-mechanical of 1955. Rigid-framed electric locomotive Rigid-framed electric locomotives were some of the first generations of design. When these began the s of these early locomotives, particularly with AC motors, were too large and heavy to be mounted directly to the axles and so were carried on the frame. One of the initial simplest wheel arrangements for a mainline electric locomotive, from around