Under the Whyte notation, a 2-8-4 is a steam locomotive that has one unpowered leading axle, usually in a leading truck, followed by four powered and coupled driving axles, and two unpowered trailing axles, usually mounted in a bogie. 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. Other equivalent classifications are: