The UIC classification of locomotive axle arrangements, sometimes known as the German classification[1]orGerman system,[2][3] describes the wheel arrangementoflocomotives, multiple units and trams. It is used in much of the world, notable exceptions being the United Kingdom and North America[a].
The classification system is managed by the International Union of Railways (UIC).[4]
The UIC uses the following structure:[4]
Garratt locomotives are indicated by bracketing or placing plus signs between all individual units.
The most common wheel arrangements in modern locomotives are Bo′Bo′ and Co′Co′.
The following examples are based on the UIC classification:[4]