A standard locomotive truck configuration featuring two bogies, each with three axles, where every axle is driven by its own independent traction motor. This six-axle design is the standard for North American heavy freight diesel locomotives because it maximizes tractive effort and distributes the engine's massive weight over more rails.
We need a pair of Co-Co units to pull that coal drag over the summit without stalling.
Do not mix it up with
- Bo-Bo: Bo-Bo has four powered axles total (two per truck) for lighter, faster trains, while Co-Co has six powered axles for heavy freight pulling power.
Related terms
Bo-Bo
A locomotive wheel arrangement featuring two four-wheel trucks with all axles powered by independent traction motors.
Traction motor
A heavy-duty electric motor geared directly to the axle of a locomotive or transit car.
Bogie
A wheeled chassis or framework attached under a rail vehicle to provide support, suspension, and guidance along the track.