Over Easy: Trains !
Passenger trains to be specific. A number of years ago, around 2009 I would say. I took an Amtrak train from Winter Park Florida to NYC. The Silver Meteor up and Silver Star back. The food was quite good and the sleeper nice and bed fairly comfortable. The ride however, was not so great. Because Amtrak rents the tracks from Washington DC south from CSX, the tracks are in horrid condition and the ride slow and bumpy.
Nearly all the train engines – if not ALL – Diesel Electric or Electric. Here is a link to a video the does a fairly goo job of explaining how a Yard Engine Diesel works. Essentially a diesel electric locomotive has a huge diesel engine – usually a two stroke diesel – that is connected to a generator and the electric power from the generator runs large electric motors on the front and real wheel axils that run the trail. It also runs an air compressor for the brakes and a few other things. These are the movers you see when stopped at a rail crossing with a very long line of freight cars.
Most locomotives use 600 Volts at up to 1000 Amps to make the train move. Originally and up until the 1980s they all used DC current for the motors and generators. But with the advent of high voltage high current solid state devices and rectifiers, AC current is used. And now the technology that is used in electric automobiles – poly phase AC motors and control – even the trains engines are beginning to use this type of motor.
Now the locomotive that pulled my passenger train had another requirement, like all passenger trains. It also had to supply electric power to the rest of the train. The sleeping cars, coaches, dining cars and all. As well as the heating and cooling. To do this the locomotive has another diesel engine / generator to to this. Separate from the one that drives the train.
Also the primary move on my Amtrak train was an electro-diesel locomotive (also referred to as dual-mode locomotive), where it could also get it’s power from overhead wires. The rail lines from Washington DC north to NYC and through Connecticut up to Boston are all electrified and diesel in not allowed. My train terminated in Penn Station in NYC.
Riding the train to NYC, I was able to see first hand how horrible the rail lines were and the rot and decay and rust of the Northern areas. Rust belt indeed.
So there was a fairly long – about 30 minutes or so – lay over in the Washington DC terminal so the switch from diesel to overhead power was made. The journey back was a bit longer and the power was off while the diesels were once again started up. This can be even longer if one has to go to a non-compatible system. Not all electrified rail uses the same system yet but it is being worked on to make them all the same. These days the electric rail all around the Philadelphia, New Jersey, NYC, Connecticut, Boston area uses 600 Volts 25 HZ AC, so any train from Pa, NJ NYC etc can run on it. There is movement to a newer, more efficient 25 kV AC at 60 Hz system in parts of the North East corridor and they have already been converted. Converting the trains currently in use is simply a matter of a transformer on the trains to step the power down.
Converting to a higher voltage lower current electrification of the rail makes even further electrification more feasible with lighter wires having to carry less current for the longer distances. An the completely electric trains are lighter and more powerful and efficient.
[Amtrak still runs The City of New Orleans]