* Traction horsepower represents the power available at the rail from the locomotive's wheels to pull a train. This accounts for losses in the drivetrain (transmission, axles, etc.).
* Wheel horsepower is the power measured *at* the wheels of the locomotive, before accounting for any frictional losses at the rail. It's a theoretical maximum that is never fully realized.
Therefore, traction horsepower is *always* less than wheel horsepower due to these unavoidable losses.
