Editing 2-8-4 (section)

==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 (steam engine)|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.

The first American 2-8-4s were built for the [[Boston and Albany Railroad]] in 1925 by [[Lima Locomotive Works]]. The railroad's route across [[The Berkshires|the Berkshire mountains]] was a substantial test for the new locomotives and, as a result, the name ''Berkshire'' was adopted for the locomotive type.

In Europe, 2-8-4 tender locomotives were designed mainly for passenger express trains, but they also hauled long-distance express freights to increase utilisation. European 2-8-4 tank locomotives were a logical transition from the 2-8-2T locomotive types, allowing larger fireboxes and larger coal bunkers. They were mainly used for busy suburban services in heavily populated suburban areas of big cities, but infrequently also for sparsely populated rural areas or long-distance lines.