2-8-4

Under the Whyte notation, a 2-8-4 is a steam locomotive that has two unpowered leading wheels, followed by eight coupled and powered driving wheels, and four trailing wheels. This locomotive type is most often referred to as a Berkshire, though the Chesapeake and Ohio Railway used the name Kanawha for their 2-8-4s. In Europe, this wheel arrangement was mostly seen in mainline passenger express locomotives and, in certain countries, in tank locomotives.

==Overview== In the United States of America, the 2-8-4 wheel arrangement was a further development of the enormously successful 2-8-2 Mikado. It resulted from the requirement for a freight locomotive with even greater steam heating capacity. To produce more steam, a solution was to increase the size of the locomotive's firebox, though the 2-8-2 wheel arrangement, with its single axle trailing truck, limited the permissible increased axle loading from a larger firebox. The most practical solution was to add a second trailing axle to spread the increased weight of a larger firebox.