Quick answer
There is no single tonnage number for a locomotive. Pulling capacity changes dramatically with grade, curvature, rail conditions, train resistance, speed and the locomotive's tractive effort.
Starting vs. keeping a train moving
A locomotive needs high tractive effort to start a heavy train. Once rolling, less force may be needed on level track, while climbing a grade can sharply increase the requirement.
Why grades matter so much
Even a modest grade adds substantial resistance when thousands of tons are involved. Railroads therefore calculate power and braking needs for the specific route rather than relying on a universal 'tons per locomotive' rule.
More locomotives do more than add horsepower
Additional locomotives add tractive effort, braking capability and—when distributed through the train—can improve how forces are managed between cars.
Keep exploring
Still curious?
Ask Ask the Conductor a railroad question in your own words.
Ask the Conductor