A performance metric for electric locomotives and traction motors indicating the highest horsepower or kilowatt load the equipment can handle for exactly 60 minutes before its insulation overheats. It is always higher than the continuous rating, allowing engineers to know how hard they can push a locomotive up a steep grade without burning out the motors.
Heard on the job
We can pull this grade at the hourly rating, but if we get stalled we'll melt the traction motors.
Related terms
Traction motor
A heavy-duty electric motor geared directly to the axle of a locomotive or transit car.
Electric locomotive
A locomotive that draws its propulsion power from an external electrical source.
Dynamic braking
Retarding force made by turning a locomotive's traction motors into generators and burning the energy off as heat.