What could an F7 pull?
- Thread starter frogpipe
- Start date
I'm no expert, plus I was born years after the time of the F7's, but I would guess that that particular lash-up could take a 2000-3000 ton train up a 2% grade without trouble. On a flat I feel that 5000 tons could be done, but with a struggle as you said. Once again, I'm no expert and this is just a guess. Perhaps an expert will come along and let us know.
http://thedieselshop.us/Data EMD F7.HTML
Continuous tractive effort 40,000 pounds, rough thumb rule is 35 pounds of tractive effort per ton being towed, so a single F7 should be able to start and keep rolling with 1,142 tons on straight level dry track. Times four engines, 4,571 tons, no idea what that comes out to in French money, but the Trainz F7 engine spec always seemed overpowered to me. I could be wrong, maybe the F7 engine spec is dead on and the specs for other engines are oversensitive to wheelslip.
Continuous tractive effort 40,000 pounds, rough thumb rule is 35 pounds of tractive effort per ton being towed, so a single F7 should be able to start and keep rolling with 1,142 tons on straight level dry track. Times four engines, 4,571 tons, no idea what that comes out to in French money, but the Trainz F7 engine spec always seemed overpowered to me. I could be wrong, maybe the F7 engine spec is dead on and the specs for other engines are oversensitive to wheelslip.
cascaderailroad
New member
An ABBA was common on long fast freights on flat lines with smooth gradients, across the US Plains States.
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Interesting bit of trivia, the Chicago & NorthWestern, which ran on mostly level track, used 4-6-2 Pacifics or those big monster H class 4-8-4 Northerns ("Zeppelins") on their fast freights, found that to keep the same track speeds with the same tonnage required two F units to replace each Pacific, 3 F units to replace a Northern. Diesel technology eventually caught up, the AC4400 with computerized anti wheelslip gadgets can haul the same tonnage as two Northerns.
cascaderailroad
New member
Set up ABBA loco consist, connect four or five 3000ton US Loaded Coal consists (12,000 to 15,000 US Tons).
Put it on a running start, straight a way, that is connected to a 5 mile long 1.75% gradient ... get it up to @ 25 mph, then full throttle once the entire consist is on the grade, and see just how far it gets without stalling
Put it on a running start, straight a way, that is connected to a 5 mile long 1.75% gradient ... get it up to @ 25 mph, then full throttle once the entire consist is on the grade, and see just how far it gets without stalling
Interesting tidbit there, sniper. Do you know what speeds/tonnage they actually ran?
For what I can guess, a good pacific =about 2000-3000 hp, just look at the PRR K4s.
And I think the N&W J pounded out 5000 hp at close to 100mph.
No idea on the freight speeds, but in passenger service they were capable of 100 mph.
"The Chicago & North Western needed more motive power for its main line operations and in 1929 received 35 very large 4-8-4s from the Baldwin Locomotive Works. These Class H Northerns (road numbers 3001 through 3035) were put to work replacing double-headed Pacifics on fast freight and passenger trains. Because of their size and weight, these new locomotives were restricted to the 488 mile Omaha - Chicago main line. They were some of the largest 4-8-4s ever built weighing in at 498,000 pounds. The tractive effort was 65,200 lbs at a boiler pressure of 250 psi as originally delivered, but later the pressure was raised to 275 psi increasing the tractive effort to 71,800 lbs. The drivers were 76" in diameter and the cylinders were 27" x 32". "
Horsepower equivalent, lessee, about 6000 depending on what you count, IIRC the later ones had superheaters and some kind of booster trucks in the tenders. Tractive effort is more important than raw horsepower, quick comparison of the first and last C&NW locos;
Baldwin 4-2-0 "Pioneer", built 1837, bought second or third hand in 1848.
Weight 24,000lbs, tractive effort 3,400lbs.
Last was;
GE AC-4400CW built in 1995.
412.000lbs, tractive effort 145,000lbs.
4400 horsepower
So despite weighing less than the "zeppelins" and having less horsepower, the AC-4400CW is more efficient at transferring that power to the rails, a little over twice the pulling power using about 2/3rds the horses.
"The Chicago & North Western needed more motive power for its main line operations and in 1929 received 35 very large 4-8-4s from the Baldwin Locomotive Works. These Class H Northerns (road numbers 3001 through 3035) were put to work replacing double-headed Pacifics on fast freight and passenger trains. Because of their size and weight, these new locomotives were restricted to the 488 mile Omaha - Chicago main line. They were some of the largest 4-8-4s ever built weighing in at 498,000 pounds. The tractive effort was 65,200 lbs at a boiler pressure of 250 psi as originally delivered, but later the pressure was raised to 275 psi increasing the tractive effort to 71,800 lbs. The drivers were 76" in diameter and the cylinders were 27" x 32". "
Horsepower equivalent, lessee, about 6000 depending on what you count, IIRC the later ones had superheaters and some kind of booster trucks in the tenders. Tractive effort is more important than raw horsepower, quick comparison of the first and last C&NW locos;
Baldwin 4-2-0 "Pioneer", built 1837, bought second or third hand in 1848.
Weight 24,000lbs, tractive effort 3,400lbs.
Last was;
GE AC-4400CW built in 1995.
412.000lbs, tractive effort 145,000lbs.
4400 horsepower
So despite weighing less than the "zeppelins" and having less horsepower, the AC-4400CW is more efficient at transferring that power to the rails, a little over twice the pulling power using about 2/3rds the horses.
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Um, ok... Why? Do you know what to expect?
To give you a somewhat comparable real world example:
When my dad was working as an engineer on the N&W in the late 1960s and early 1970s, he operated 5 GP9s on trains that hauled 100 (loaded) coal cars from Mullens, WV up a 13.4 mile long 2% grade to Clarks Gap, WV, where he would pick up 100 more (loaded) coal cars and then continue on with the 200-car train to Roanoke, Virginia, with grades no greater than .6 percent. On the return trip the same engine lashup would be used to haul 200 (empty) coal cars all the way back to Mullens, WV, with grades no greater than 1.6 percent. Since most coal cars in use then were in the 90-100 ton range the 100 car train probably was around 8618 metric tons; the 200 car train about 17236 metric tons. Both figures wouldn't include the weight of the cars themselves, when empty.
Horsepower rating for a single F7 unit = 1500. For a single GP9 unit the horsepower rating=1750, a little higher than the F7. So 4 F7 units = 6000 horsepower vs. 8750 hp for five GP9 units.
So, about 75% of the power. So you could maybe think 75% of the load.... around 6000t, again I don't know what the gade was, but you could see it, so it wasn't .6% or flat. I was able to throttle up to near full Amps without wheelslip, so for a game, I think it's pretty close...
The diesels in Trainz seem to be pretty darn close to the real thing in terms of pulling power and the way they respond under cab control.
Just looked through some of my books on the C&O and found a pic of three F7s handling a 160 car (loaded) coal train along the Ohio River, east of Greenup, KY.
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cascaderailroad
New member
I hooked up a 15,000 Ton US Loaded Coal train and in Cab mode it very soon stalled on a 1.75% grade, even while using traction sand.
However in DCC mode it ran without slowing down.
However in DCC mode it ran without slowing down.
When discussing physics CAB mode is taken for granted, the whole point of DCC mode is simple model railroad stop-go-reverse for the kids who just want to run trains.
Even says "simple physics model" on the label, so there's no point in even trying to adjust physics for DCC mode.
Even says "simple physics model" on the label, so there's no point in even trying to adjust physics for DCC mode.
64Warhorse
New member
There's a set of pages here: http://www.alkrug.vcn.com/rrfacts/rrfacts.htm that have quite a lot of interesting and useful information about real life railroading. The "Horsepower vs Tractive Effort" page is particularly relevant to this discussion.