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.
American Locomotive Company
Alco was the second-largest steam locomotive builder in the United States (after Lima Locomotive Works), producing over 75,000 locomotives (though not all were steam, since, unlike Baldwin, Alco transitioned more readily to Diesel). Among these were a large number of well-known locomotives. Railroads that favored Alco products included the Delaware & Hudson Railway, the New York, New Haven & Hartford Railroad, the New York Central Railroad, the Union Pacific Railroad and the Milwaukee Road. Alco was known for its steam locomotives of which the 4-6-4 Hudson, 4-8-2 Mohawk and the 4-8-4 Niagara built for the New York Central and the 4-8-4 FEF and the 4-6-6-4 (Challenger) built for the Union Pacific were fine examples. Alco built many of the biggest locomotives ever constructed, including Union Pacific's "Big Boy" (4-8-8-4). Alco also built the fastest American locomotives, the Class A Atlantic and Class F7 Hudson streamliners for the Milwaukee Road's "Twin Cities Hiawatha" run. Among the ambitious state-of-the-art designs of the late steam era, Alco's Challengers, Big Boys and high speed streamliners stood out for their in-service success.