Hot Water posted:wjstix posted:Many railroads running FTs found a problem due to their being designed to run as A-B sets with drawbars. Each unit created 1350 horsepower, so an A-B set had 2700 HP, and two A-B sets coupled back-to-back had 5400HP. At that time, mainline freights required around 4000 HP. So the FTs had sort of a "Goldilocks" problem - one A-B set didn't have enough horsepower, and two sets (back-to-back A-B-B-A) had a lot more power than needed.
There was no such thing as a normal horsepower requirement for main line freight trains. I'd like to know where that 4000 number came from. Must have been on railroad that had a fairly constant train length and normal operating speed, and only on that part of the railroad that had the same topological characteristics like the UP between Omaha and Cheyenne.
Horsepower needed depended on train resistance which varies with tonnage, speed and grade. Rolling resistance is proportional to the speed and wind resistance to the square of the speed.
Ruling grade and short time ratings were other factors. No way there could be a usual horsepower common to many railroads.
