HP is the single biggest predictor of performance. Torque can be gained through gearing, which is why a 20HP tractor can pull a house. If torque were king, Super Duty diesels would be dragsters. HP is independent of gearing.
My first Ford only made 18 HP at the rear wheels! 1950 Ford 8N. 2.0L (120 C.I.) flathead 4. 2,000 RPM. 92 lb-ft torque! What a little beast! Pull stumps, drag trees around, brush hop, whatever. The 8N was nice, had the 4-speed, 9N did not. U.S. Air Force had a special version with a straight 6. You are right on about HP/RPM. I could make about 20 plus mph. Used to pull all the neighborhood kids around on an old hay trailer Thanksgiving and Christmas holidays, they loved it.
Close, but not quite. I am a retired locomotive engineer. (2nd career after the military) A locomotive has a nice 4,500 HP diesel unit hooked up to a generator about the size of a large truck. That electricity is delivered directly to the electric motors. There is no HVB like our trucks. There is a bank of several batteries for starting and maintaining basic instrumentation and such. For braking, we did have "dynamic braking", basically regenerative braking similar to our Mav's. Big difference is how it is operated. We manually can utilize dynamic braking to include how much of it whenever we want with a push of the lever. A locomotive's motors between the wheels act both as a motor and a generator. Any excess power is dissipated as heat out the "grid units on the roof. Seen a few of those get a little hot and man, like molten lava. If you are lucky you don't catch fire! Ha!
But what strikes me so weird about diesel locomotives is the energy wasted by dynamic braking….heat, when it could be recharging batteries either onboard or in tender
Not weird when you think about how impractical it would be. Not worth the cost. Cost is high. Benefits low. Logistics difficult.
Yes, I could see it might be cost justified for a locomotive designed to just move the rail cars around in the rail yard with many starts and stops all day long. But for the majority of locomotives designed to move long distances it would not get used enough to justify the cost.
