The wheel arrangement on large diesel locomotives is described using the UIC classification system. Those in use on the SVR are as follows:
- B-B: Four powered axles all mounted in the locomotive's frame, driven in pairs, i.e. each pair of axles is connected by driving rods or gears.
- Bo-Bo: Four axles in two individual bogies, all driven by their own traction motors.
- C-C: Two bogies or wheel assemblies under the unit. Each bogie has three powered axles, mechanically connected by driving rods or gears.
- Co-Co: Two six-wheeled bogies with all axles powered, with a separate motor per axle.
- 1Co-Co1: Two six-wheeled bogies with all axles powered, with a separate motor per axle with an additional unpowered carrying wheel at the end of each bogie to reduce axle load.
The wheel arrangement on steam locomotives and small diesel locomotives is described using Whyte notation.