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Well, if I have remembered correctly, train power equipment is not that fundamentally different from dedicated electrical power generating equipment. In fact,

Well, if I have remembered correctly, train power equipment is not that fundamentally different from dedicated electrical power generating equipment. In fact, I believe for a lot of engines, the mechanical energy rarely is used directly to power wheels -- it usually (for diesel-electric, for example) is powering a generator that then is feeding electricity to motors + wheels. So, maybe not such a stretch to take the power/electricity off to other purposes?

NamTaf 6y ago
Correct. Modern locos basically receive AC, convert it to DC, then convert it back to AC for the traction motors. Whether they receive AC through a pantograph, or a self-contained engine + generator, doesn’t really make a whole lot of difference. The power generation is fundamentally the same as in marine purposes, too. In fact, the modern engines such as the EMD 710 or GE 7FDL, often come in non-mobile stationary/marine operation configurations for these purposes.
Teknoman117 6y ago
I don't know of any that actually have mechanical linkages. The whole point is to use the alternator + electric motors as a CVT basically. You want the engine to be able to use it's maximum power at any given speed. The amount of gears you'd need for a mechanical transmission for the big freight locomotives would be absurd.
- namibj 6y ago
  There are diesel-hydraulic locomotives, which use a torque converter (and optionally a transmission) between the driven wheels and the engine.
eigenvector 6y ago
Correct, most modern locomotives are diesel-electric and not fundamentally different from a large standby generator that would be found in a hospital or data center. The locomotive has the great advantage of being easy to move, although a bit of MacGyvering would have been needed on the control/operation side since a traction power engine probably doesn't have a ready-made 60 Hz governor control.
johnwalkr 6y ago
Some replies already, but just to add (sorry, train nerd here).. It's not for a lot of locomotives, but virtually all locomotives. Early diesel locomotives tried to use a mechanical transmission but this mostly failed because you can't scale the technology up well, and this is my own speculation but I think you need to be able to shift under full load. The transition from steam didn't happen until diesel-electric was invented. This combination is also good for reducing wear on brakes, as you can use the motor as a generator and resistors to dissipate power as heat. I don't know of a locomotive that uses regenerative braking, but it's used on some passenger trains in Japan. Not by storing energy in batteries, but by feeding into the local power grid! Diesel-hydraulic was also tried for a while but was largely unsuccessful. For special applications, like maintenance equipment or moving things in a railyard, you can still find some diesel-mechanical and diesel-hydraulic equipment. If a freight train stops, depending on its length, it must reverse to add slack between cars. Then it starts by effectively pulling each car one by one. You can hear it as a bang-bang-bang if you're nearby, depending on the coupling method between cars. If a train loses momentum on a hill, it may have to reverse and start from the bottom.

NamTaf 6y ago

Correct. Modern locos basically receive AC, convert it to DC, then convert it back to AC for the traction motors. Whether they receive AC through a pantograph, or a self-contained engine + generator, doesn’t really make a whole lot of difference. The power generation is fundamentally the same as in marine purposes, too. In fact, the modern engines such as the EMD 710 or GE 7FDL, often come in non-mobile stationary/marine operation configurations for these purposes.

Teknoman117 6y ago

I don't know of any that actually have mechanical linkages. The whole point is to use the alternator + electric motors as a CVT basically. You want the engine to be able to use it's maximum power at any given speed. The amount of gears you'd need for a mechanical transmission for the big freight locomotives would be absurd.

namibj 6y ago
There are diesel-hydraulic locomotives, which use a torque converter (and optionally a transmission) between the driven wheels and the engine.

eigenvector 6y ago

Correct, most modern locomotives are diesel-electric and not fundamentally different from a large standby generator that would be found in a hospital or data center. The locomotive has the great advantage of being easy to move, although a bit of MacGyvering would have been needed on the control/operation side since a traction power engine probably doesn't have a ready-made 60 Hz governor control.

johnwalkr 6y ago

Some replies already, but just to add (sorry, train nerd here).. It's not for a lot of locomotives, but virtually all locomotives. Early diesel locomotives tried to use a mechanical transmission but this mostly failed because you can't scale the technology up well, and this is my own speculation but I think you need to be able to shift under full load. The transition from steam didn't happen until diesel-electric was invented. This combination is also good for reducing wear on brakes, as you can use the motor as a generator and resistors to dissipate power as heat. I don't know of a locomotive that uses regenerative braking, but it's used on some passenger trains in Japan. Not by storing energy in batteries, but by feeding into the local power grid! Diesel-hydraulic was also tried for a while but was largely unsuccessful. For special applications, like maintenance equipment or moving things in a railyard, you can still find some diesel-mechanical and diesel-hydraulic equipment. If a freight train stops, depending on its length, it must reverse to add slack between cars. Then it starts by effectively pulling each car one by one. You can hear it as a bang-bang-bang if you're nearby, depending on the coupling method between cars. If a train loses momentum on a hill, it may have to reverse and start from the bottom.