Picked up a 1971 book at half price books titled: Management of train operation and train handling. It covers topic basics of train brake systems, dynamic braking, valve types, remote control types, passenger train handling etc.
What was most interesting was the technical appendix. topics were: effects of gear ratios, air resistance of consist, mixing different engines (4 and 6 motored units, mixing a little SWxx in with the big 3000 HP ), horsepower differences, wheel slip calculations vs curves and gradients, traction effort per wheel vs curves and gradients, braking effort per wheel on curves and descending grades, how fast or slow they can run because of that little SWxx in the mix, on and on.
While a very interesting read, chuckled wondering how many engineers sit in the cab worrying about gear ratios, tractive effort per ton, how much braking need going down the grade and all other factors. I assume the yard couples up just enough engines to get the job done and sends it off to haul away the 5000+ ton consist, and done. 
