2-8-8-4 2-8-8-4 A 2-8-8-4 steam locomotive, under the Whyte notation, has two leading wheels, two sets of eight driving wheels, and a four-wheel trailing truck. The type was generally named the "Yellowstone", a name given it by the first owner, the Northern Pacific Railway, whose lines run near Yellowstone National Park. Seventy-two Yellowstone-type locomotives were built for four U.S. railroads. Other equivalent classifications are: The equivalent UIC classification is, refined for Mallet locomotives, (1′D)D2′. A locomotive of this length must be an articulated locomotive, and each 2-8-8-4 had a joint in the frame between the first and second groups of driving
2-8-8-2 still used on steel mill lines and other railroads until 1983. Other equivalent classifications are: UIC classification: 1DD1 (also known as German classification and Italian classification) French classification: 140+041 Turkish classification: 45+45 Swiss classification: 4/5+4/5 The first 2-8-8-2 was built in 1909 by Baldwin, who sold two to the Southern Pacific Railroad (classified MC-1), and then three each to the Union Pacific Railroad and UP-owned Oregon Railroad and Navigation Company. Baldwin conceived the type as an expansion of the 2-6-6-2 permitting a greater tractive effort. The next order for the type was from the Southern Pacific; these differed in being