Bo'Bo'Bo'

A Bo-Bo-Bo or Bo'Bo'Bo' in UIC classification is a locomotive with three independent two-axle bogies with all axles powered by separate traction motors. In the AAR system, this is simplified to B-B-B.

The Bo-Bo-Bo configuration is often used to lower axle weight while keeping lateral forces low compared to a locomotive with two three-axle bogies, thus allowing the locomotive to use lightly laid track, in particular narrow-gauge railways.

The arrangement is extensively used on Italian and Japanese railways. Other examples include New Zealand's DJ, EW and EF classes; the Eurotunnel Class 9 locomotives, which were themselves derived from the New Zealand EF class; the Swiss SBB Re 6/6 (Re 620); the Russia Railways EP10, and the South Korean Korail Class 8000. China imported 6K electric locomotive from Japan between 1986 and 1987. The Bo-Bo-Bo design was applied to SS7 series except SS7E.

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