ABB traction motors - locomotive

Freight locomotives must be strong enough to start with full load at demanding inclines. Their speed is relatively low, up to 160 km/h, which allows for cost-effective axle-hung mounting of the traction motors.

To enable a high tractive effort, the motors have a high torque‑space ratio. Mounting the motor directly to the gearbox and wheel shaft (axle-hung) maximizes the available space for the motor and ensures a high torque-space ratio.

Given the strong forces and heavy loads, the bearings must be big enough to provide a high load carrying capacity. However, large bearings mean high peripheral speeds, calling for oil lubrication of the drive-side bearing.

ABB’s locomotive motors typically come with a welded stator frame to optimize the tight space envelope. Analyses let us optimize e.g. the trade-off between bearing and lubricant lifetime.

These trains operate at relatively high speeds. Therefore the vehicle’s unsuspended mass must be kept as low as possible to reduce wear of the rail and vehicle. A coupling between motor and gearbox makes the traction motors suspended (bogiehung), allowing the locomotive to operate at high speeds.

The coupling makes the bogie-hung solution less torque dense than the axle-hung solution. However, the mechanical stress is lower, allowing the motor to be more lightweight than freightlocomotive motors. The bearings can be made smaller, allowing the use of grease lubrication even at high vehicle speeds.

Over the years, we have gradually r efined our motors to near perfection. Today, more than 3,000 ABB traction motors are in operation in locomotives worldwide. Our motors come with a robust welded stator frame, bearings and grease adapted for high-speed operation, and proven stator and rotor technologies.