30 of these giants were made in the mid-1940s by the Norfolk and Western railway's Roanoke shops, and are the strongest steam locomotives ever made, even stronger than the Union Pacific big boys, which are commonly mistaken as the strongest. These bad roller bearings on all axles and automatic lubrication systems, allowing them to be turned around, cleaned, serviced, and ready for the next train in under an hour. Y6bs, along with their Y6a counterpart, hauled heavy coal trains up the N&W's mountain regions until 1959, when they were retired. #2178 would pull excursions until 1960, when it was layed up for scrap until 1974, when despite the scrap dealer keeping it in case someone could make up the funds to but it, a change in management spelt the scrapping of the engine, rendering the y6b class extinct, though one Y6a, 2156 is on display in St. Louis.
