Allocation of motive power to consists

[sepp1961]

After browsing thru an old train magazine I came across a photo of 2 F-units pulling a 70 freight car consist. In the same magazine was a picture of 2 FP45's pulling 10 passenger coachs, talk about a waste of tractive effort! I can understand the excessive power when it comes to moving consists over mountianous terrain but across the flatlands of the midwest? Does anyone out there have any idea on how power is assigned to consists?

[TomDiehl]

There's a LOT more to consider than just the number of cars. Grades and curves GREATLY reduce the number of cars a given locomotive can pull as compared to straight and level track. If you've heard the term "ruling grade" that's what it means. The maximim grade for a given section of track (usually a division) and trains are usually powered for this grade unless pushers are to be used. Next, passenger coaches are much heavier and require more tractive effort than the same number of freight cars. If the passenger cars are being used in commuter service (a lot of stop and go) the acceleration of the train also becomes a factor in keeping to the schedule, so more horsepower is needed.

Just a few considerations off the top of my head.

[Trainnut484]

Railroads also needed to balance out power along the system as well. There were trains with as much as 12 units long. The extra power per tonnage wasn't needed, but power was needed elsewhere on the system. Today, railroads still do some "power balancing", but not as much.

Take care,

Russell