Hoerner has a section on trains in his book,"Aerodynamic Drag." I'll dig it out and post that,but I think Bicycle Bob and Big Dave have covered the fundamentals of it.Next to water transport,the train is the most efficient form of transport even as imperfect as it is.
There is a large diesel engine running that is connected to a even larger generator. This charges batteries and powers motors in each truck.
Actually the prime mover (the diesel engine) in a modern locomotive is massive, not just large. For an example, the old EMD 567 prime mover was so named because each cylinder was 567 cu.in.!! Even an older inline 6 from, let's say, an old Alco is massive. Also, the main generator is much smaller compared to the prime mover, not larger.
People may think that the main generator charges batteries for powering the traction motors, that is incorrect. Locomotives do have a bank of batteries, but mainly for ancillary uses and of course for starting the prime mover. The batteries have nothing to do with powering the traction motors; all power comes from the main generator. GE does have a hybrid loco in the works that uses energy dissipated from braking (from the dynamic brakes), and uses it to power the motors on-demand, giving the engineer about 2000 h.p. for traction when necessary.
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Some of the larger locos even have 2x motors per truck.
You seem to be implying that some axles are un-powered. ANY modern locomotive has all axles powered (i.e. one traction motor for each axle). 6 axles = 6 motors.
well, they claim to be able to move a ton of freight over 400 miles on a gallon of fuel...
And here's why I hate that "commercial"...One single coal car has a loaded weight of 110 tons (as per wikianswers, although I did find another source that specified "120 ton coal cars" so it does seem plausible), which means when you see a loaded coal train with over 200 cars (I used to count the cars when I was a kid since there's not much else to do in a really small town), they're not getting 400+mpg.
1 ton = 400mpg
110ton = 3.64mpg
22,000ton = 0.018mpg
Still more efficient than a semi, but I just hate when people so obviously lie with statistics, even when they're telling the truth.
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*Time period is from 1 January 2006 - 1 March 2007*
Volones you bring up something interesting....
So there's a coal mine in Healy, AK. It's about 400 rail miles to Anchorage, AK. I normally will see 50 coal cars behind 3 engines. So taking the 1T/1 gal for 400 miles,
50 cars*110T=5500T
5500T/xT *1T/1 gal = 5500 gal
400 miles/5500gal = 0.07273 m/g
That's terrible if you ask me. But that's only if you look at general fuel consumption. Specific fuel consumption...
My car: 1.5T, 32mpg. over 400 miles that's 12.5gal.
12.5gal/1.5T = 8.333 gallons to move 1 Ton. Not so impressive to the 1 gallon per 1 Ton.
I need at least 266mpg to match the train's efficiency at moving mass. The Loremo comes close at 180mpg, and the VW sausage thing (can't remember the name) can do it at 261mpg. I personally want a Loremo.
Not arguing, just illustrating for all to see how efficient trains are despite the poor aerodynamics.
almightybmw,
I fully agree that a train is still more efficient at transporting huge loads over long distances. what I don't like is the little blurb they put on NPR saying that the train can move 1 ton 400 miles on a single tank of fuel, when in reality no trains ever carry only 1 ton of anything. The cars weigh more than that empty. And yes, I'm arguing semantics here, I'm fully aware of that.
Vol
BTW, I was too lazy to compute the efficiency of an auto in moving 1 ton, thanks for doing that it's pretty eye opening.
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*Time period is from 1 January 2006 - 1 March 2007*
Volones you bring up something interesting....
So there's a coal mine in Healy, AK. It's about 400 rail miles to Anchorage, AK. I normally will see 50 coal cars behind 3 engines. So taking the 1T/1 gal for 400 miles,
50 cars*110T=5500T
5500T/xT *1T/1 gal = 5500 gal
400 miles/5500gal = 0.07273 m/g
That's terrible if you ask me. But that's only if you look at general fuel consumption. Specific fuel consumption...
My car: 1.5T, 32mpg. over 400 miles that's 12.5gal.
12.5gal/1.5T = 8.333 gallons to move 1 Ton. Not so impressive to the 1 gallon per 1 Ton.
I need at least 266mpg to match the train's efficiency at moving mass. The Loremo comes close at 180mpg, and the VW sausage thing (can't remember the name) can do it at 261mpg. I personally want a Loremo.
Not arguing, just illustrating for all to see how efficient trains are despite the poor aerodynamics.
Just remember, they're specifying per ton of freight. Your car is not hauling 1.5T of freight at 32 mpg.
On top of that, it'd be fairly simple (technically) to electrify any given stretch of track, so that trains potentially would need not use any fossil fuel at all.
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