Under the Whyte notation for the classification of steam locomotives by wheel arrangement, represents the arrangement of six unpowered leading wheels arranged into a three-axle leading truck, eight powered driving wheels, and six unpowered trailing wheels arranged into a three-axle trailing truck. Other equivalent classifications are: UIC classification: 3D3 (also known as German classification and Italian classification) French classification: 343 Turkish classification: 410 Swiss classification: 4/10. The only known example of the 6-8-6 wheel arrangement is the experimental Pennsylvania Railroad S2 steam turbine locomotive. Notes References 8,6-8-6