2-8-8-2

A 2-8-8-2, in the Whyte notation for describing steam locomotive wheel arrangements, is an articulated locomotive with a two-wheel leading truck, two sets of eight driving wheels, and a two-wheel trailing truck. The equivalent UIC classification is, refined to Mallet locomotives, (1'D)D1'. These locomotives usually employ the Mallet principles of articulation--with the rear engine rigidly attached to the boiler and the front engine free to rotate--and compounding. The 2-8-8-2 was a design largely limited to American locomotive builders.