LNER Class A4
The Class A4 is a class of streamlined 4-6-2 steam locomotive designed by Nigel Gresley for the London and North Eastern Railway in 1935. Their streamlined design gave them high-speed capability as well as making them instantly recognisable, and one of the class, 4468 "Mallard", holds the world record as the fastest steam locomotive. Thirty-five of the class were built to haul express passenger trains on the East Coast Main Line route from London Kings Cross via York to Newcastle, and later via Newcastle to Edinburgh, Scotland. They remained in service on the East Coast Main Line until the early 1960s when they were replaced by Deltic diesel locomotives. Several A4s saw out their remaining days until 1966 in Scotland, particularly on the Aberdeen - Glasgow express trains, for which they were used to improve the timing from 3.5 to 3 hours.
Chessie (train)
To pull the "Chessie" the C&O ordered three experimental steam turbine locomotives from the Baldwin Locomotive Works. As diesel locomotives became more prevalent following World War II, the C&O was one of several railroads loath to abandon coal as a fuel source, and saw steam turbine technology as a possible alternative to diesel. At the time of their construction these locomotives were the longest single-unit locomotives in the world. Not including research and development, the three locomotives cost . The M1s proved a failure in operation and were scrapped in 1950.