I have a question. Why are GE's AC4400's more popular then their big brother, the AC6000? Is it price? Fuel efficiency? Too much power?
The extra horsepower is useful only for higher speed or faster acceleration, neither of which is beneficial in freight service. In pure lugging power both locomotives are equal.
Read Al Krug's detailed explanation at
http://www.alkrug.vcn.com/rrfacts/hp_te.htm
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"A stranger's just a friend you ain't met yet." --- Dave Gardner
I am gonna first off say that I am no expert period, but I think I can help. I know the AC6000s were supposed to be end be all locomotive from GE to stomp out EMD and there at the same time new SD90s. I think that UPs have been derated and possibly CSX has either derated or kept the same power rating. Not sure but I read these at diff times. The AC6000s dont meet the tier 3 EPA requirments anymore, which is another reason they dont make them. They are incredible in person! Guess I was lucky had some family work for the RRs but they are all retired now. God Bless
beaulieu The extra horsepower is useful only for higher speed or faster acceleration, neither of which is beneficial in freight service. In pure lugging power both locomotives are equal.
-Don (Random stuff, mostly about trains - what else? http://blerfblog.blogspot.com/)
macsdace70 I am gonna first off say that I am no expert period, but I think I can help. I know the AC6000s were supposed to be end be all locomotive from GE to stomp out EMD and there at the same time new SD90s. I think that UPs have been derated and possibly CSX has either derated or kept the same power rating. Not sure but I read these at diff times. The AC6000s dont meet the tier 3 EPA requirments anymore, which is another reason they dont make them. They are incredible in person! Guess I was lucky had some family work for the RRs but they are all retired now. God Bless
CSX has installed 16 cylinder FDL engines on a few of its AC60Cws essentially making them AC4400CWs but the majority of them are being rebuilt with new 16 cylinder GEVO engines and will retain their 6000 HP rating.
GE has also recently built some brand new ES59AC(16 clinder GEVO 5,900HP) units for a customer in Brazil in addition to the large number of locomotives and parts they are supplying to China for their new 6,000 HP units.
There is the Tier III issue but that is also a problem for the other GEVO units (neither the ES44AC or ES44DC is currently Tier 3 compliant but they are working on it..)
"I Often Dream of Trains"-From the Album of the Same Name by Robyn Hitchcock
Paul of Covington Read Al Krug's detailed explanation at http://www.alkrug.vcn.com/rrfacts/hp_te.htm
The idea that you need engineering margin on adhesion is not new.
I can see a scenario where you are using that fancy Buck Rogers wheel slip control on a high horsepower locomotive on a commuter train. Even if the rails are slickened with frost or leaves, you may not accelerate as quickly and perhaps end up late according to schedule, but you won't get stuck. On the other hand, if you are relying on that fancy wheel slip control to get a heavily laden freight up a hill -- good luck!
The one question I have is when the fancy new locomotive is down to 22% adhesion on account of wet rails, is the SD-40 also at 40% adhesion, or is that down to, say, 11% under the same conditions? It may be that wet rails you have to "de-rate" your locomotives, but that the wheel slip control still does better than a comparable locomotive without it?
If GM "killed the electric car", what am I doing standing next to an EV-1, a half a block from the WSOR tracks?
Paul Milenkovic Paul of Covington: Read Al Krug's detailed explanation at http://www.alkrug.vcn.com/rrfacts/hp_te.htm The idea that you need engineering margin on adhesion is not new. I can see a scenario where you are using that fancy Buck Rogers wheel slip control on a high horsepower locomotive on a commuter train. Even if the rails are slickened with frost or leaves, you may not accelerate as quickly and perhaps end up late according to schedule, but you won't get stuck. On the other hand, if you are relying on that fancy wheel slip control to get a heavily laden freight up a hill -- good luck! The one question I have is when the fancy new locomotive is down to 22% adhesion on account of wet rails, is the SD-40 also at 40% adhesion, or is that down to, say, 11% under the same conditions? It may be that wet rails you have to "de-rate" your locomotives, but that the wheel slip control still does better than a comparable locomotive without it?
Paul of Covington: Read Al Krug's detailed explanation at http://www.alkrug.vcn.com/rrfacts/hp_te.htm
The new wheelslip systems, particularly when combined with AC traction motors, are that much better than the older systems like GM's Super Series or GE's MicroSentry. Figure 24% maximum for a SD40-2 unless it has an aftermarket wheelslip system. Under rail conditions where a modern AC locomotive is down to 24% factor of adhesion the SD40-2 or GE late model Dash7 would be in single digits or stalled. The modern GE system for AC locomotives can vary the torque being produced by each individual axle. So the computer can reduce the torque being produced by the lead axle as it will encounter the worst rail conditions, but it will sense any individual axle slipping and transfer power to the other 5 to keep total tractive effort at the desired level. Nothing remotely like this is possible with a DC series wound motor as used on all DC locomotives in North America. There are a few Diesel-electrics in Europe with separately excited DC traction motors (BR Class 60 is the best known), but they are rare.
I think that it helps to clarify traction control if a distinction is made between wheelslip control and creep optimization. Although the traction control systems on AC-traction locomotives do prevent loss of adhesion by controlling wheelslip, they maximize adhesion by optimizing creep rate in response to changing conditions. One of the weaknesses in the traction control systems of early AC-traction units was an inability to measure ground speed with consistent accuracy. When a system's value for ground speed was too low, the system functioned as if the creep rate was too high; and instead of adjusting creep to the optimum rate, the system reduced it to a rate that was actually too low.
Hey thanks got it! I read the same articles as you somewhere. May have been in trains mag. I should have been a little more "reaserch" first. I do not have a lot of time as me and my wife are both iron workers and I am a veteran and my son is in the Army Infantry. God Bless All
Very good comments all around. I would add one more piece. When the AC6000CW was introducing in December of 1995 the AC4400CW had been around for just over a year. Production AC transmission locomotives were a new reality on the railroads and they were still 'feeling their way' as to application and the upper limit of their power. The 6K hp offerings from GE and EMD had issues at the start and those have resulted in either improvements or retirements. In the intervening decade and a half the 4-4.5K hp locomotive has become the standard for road power much in the same way that 3K hp became the standard a generation earlier. Sizing a train for a 6K hp locomotive when only 4K hp is available becomes a dispatching headache. The 3K hp standard lasted about 25-30 years so eventually the horsepower war will heat up again.
Very good comments all around. I would add one more piece. When the AC6000CW was introducing in December of 1995 the AC4400CW had been around for just over a year. Production AC transmission locomotives were a new reality on the railroads and they were still 'feeling their way' as to application and the upper limit of their power. The 6K hp offerings from GE and EMD had issues at the start and those have resulted in either improvements or retirements.
In the intervening decade and a half the 4-4.5K hp locomotive has become the standard for road power much in the same way that 3K hp became the standard a generation earlier. Sizing a train for a 6K hp locomotive when only 4K hp is available becomes a dispatching headache. The 3K hp standard lasted about 25-30 years so eventually the horsepower war will heat up again.
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So why don't the locomotive companies put more into adhesion then horsepower? From Paul of Covington's post, it sounds like that is equal to, or almost more important than Hp.
Those AC 6000's are one mean locomotive!I remember when I was working for the Union pacific as a hostler and I saw one for the first time I was just awstuck.That locomotive would shake the ground just sitting there.6000 hp and twin turbo it was king of the yard.It is also one of the best designed locomotives I have ever seen.
One of the problems with that locomotive is it loads up very fast.I remember we had a train with a AC 6000 on the lead and you would push the throttle into notch 1 and it would be loaded up,trying to pull the entire train while the rest of the units behind it were just getting started.So I think it works best if it is teamed up with other fast loading locomotives or as a pusher unit.In Colorado where I live you see them all the time on coal trains over the moffat line.They are typically mid train and rear helpers.
farmingrailroader So why don't the locomotive companies put more into adhesion then horsepower? From Paul of Covington's post, it sounds like that is equal to, or almost more important than Hp.
A 3000 HP DC six axle and a 6000 HP AC six axle have roughly the same ratio of HP to max tractive effort, so, early on, the 6000 HP AC unit was seen as the replacement for the 3000 HP DC unit. Two AC units could replace four DC units on a train and give equivalent performance in speed and running time. So, the push was on to build and acquire 6000 HP AC units. The industry was so eager that UP took delivery on "convertibles" - locomotives delivered with 4300HP diesel engines that could be simply upgraded to 6000 HP engines just by swapping out the diesel engine, once EMD could provide them. Conrail took 5000 HP SD80MACs as a "close as you can get without chancing a new engine design" solution.
Some RRs also took delivery of 4000-4400 HP AC six axles to use for unit train service, notably SP and BN, where the game is all about just being able to get heavy trains over the ruling grade and HP is a secondary issue.
Along the way, two things changed. One, the early 6000 HP AC locomotives proved to have reliability issues that were not so easily resolved. Two, RRs found in many instances, the trade-off between fuel and speed fell in favor of the fuel. That is, fuel savings they got from replacing four, 3000 HP DC units with two 4400 HP AC units was worth the somewhat longer running times.
D.Carleton Very good comments all around. I would add one more piece. When the AC6000CW was introducing in December of 1995 the AC4400CW had been around for just over a year. Production AC transmission locomotives were a new reality on the railroads and they were still 'feeling their way' as to application and the upper limit of their power. The 6K hp offerings from GE and EMD had issues at the start and those have resulted in either improvements or retirements. In the intervening decade and a half the 4-4.5K hp locomotive has become the standard for road power much in the same way that 3K hp became the standard a generation earlier. Sizing a train for a 6K hp locomotive when only 4K hp is available becomes a dispatching headache. The 3K hp standard lasted about 25-30 years so eventually the horsepower war will heat up again.
I would tend to agree. I think what might push it along is the continuing growth of intermodal traffic where higher HP per ton is generally the rule. A 6000 HP AC is a better fit than a 4400 HP AC six axle. If a good 6000 HP AC unit were available now, I'd bet BNSF would have gone for them rather than the 4400 HP A-1-A AC's they've recently purchased. Three 6000 HP ACs could replace four of the A-1-As on their transcon route without missing a beat.
CSXT hoped that two AC6000CWs could replace three 4,000-hp DC-traction units in intermodal service; however as Don indicated, there were reliability issues with the two-unit 6,000-hp consists. CSXT tried three-unit consists of 4,400-hp DC-traction units; however after determining that this often involved excessive horsepower, it decided that the typically optimum consist is three 4,000-hp DC traction units. However it has continued to work with GE to improve AC6000CW reliability and has not ruled out the possibility of regularly assigning two-unit AC6000CW consists to intermodal service.
Motors are not excited, generators are.
But I can get excited over motors.
From oltmannd:
"The trick is to strike the right balance between HP and tractive effort (adhesion) for the service the locomotive is going to perform"
I think the key word here is "balance." From what I took from Al Krug's explanation, as relates to the original question, is that in most cases the extra horsepower just isn't needed for the adhesion available. The main use for high horsepower would be the high speed service such as hot intermodal trains.
oltmannd D.Carleton: Very good comments all around. I would add one more piece. When the AC6000CW was introducing in December of 1995 the AC4400CW had been around for just over a year. Production AC transmission locomotives were a new reality on the railroads and they were still 'feeling their way' as to application and the upper limit of their power. The 6K hp offerings from GE and EMD had issues at the start and those have resulted in either improvements or retirements. In the intervening decade and a half the 4-4.5K hp locomotive has become the standard for road power much in the same way that 3K hp became the standard a generation earlier. Sizing a train for a 6K hp locomotive when only 4K hp is available becomes a dispatching headache. The 3K hp standard lasted about 25-30 years so eventually the horsepower war will heat up again. I would tend to agree. I think what might push it along is the continuing growth of intermodal traffic where higher HP per ton is generally the rule. A 6000 HP AC is a better fit than a 4400 HP AC six axle. If a good 6000 HP AC unit were available now, I'd bet BNSF would have gone for them rather than the 4400 HP A-1-A AC's they've recently purchased. Three 6000 HP ACs could replace four of the A-1-As on their transcon route without missing a beat.
D.Carleton: Very good comments all around. I would add one more piece. When the AC6000CW was introducing in December of 1995 the AC4400CW had been around for just over a year. Production AC transmission locomotives were a new reality on the railroads and they were still 'feeling their way' as to application and the upper limit of their power. The 6K hp offerings from GE and EMD had issues at the start and those have resulted in either improvements or retirements. In the intervening decade and a half the 4-4.5K hp locomotive has become the standard for road power much in the same way that 3K hp became the standard a generation earlier. Sizing a train for a 6K hp locomotive when only 4K hp is available becomes a dispatching headache. The 3K hp standard lasted about 25-30 years so eventually the horsepower war will heat up again.
I seem to recall that both UP and CSX generally run(or ran) 6000HP locomotives in 2 unit sets. My understnding is that it is uncommon to run 18000HP AC traction consists on the head end of a train (can't that damage draft gear?) . The Chinese are supposedly running their new 6,000HP units in 3 unit sets on Mineral trains (maybe the Australians as well) but at lower speeds I don't see the advantage...
Also, the BNSF philosophy on the ES44C4 seems to be for three A-1-A AC units to replace a like number of six axle DC motored 4400 HP units on fast freights (same number of units but fuel and maintenance costs are supposed to be reduced with same or better performance)..
carnej1 oltmannd: D.Carleton: Very good comments all around. I would add one more piece. When the AC6000CW was introducing in December of 1995 the AC4400CW had been around for just over a year. Production AC transmission locomotives were a new reality on the railroads and they were still 'feeling their way' as to application and the upper limit of their power. The 6K hp offerings from GE and EMD had issues at the start and those have resulted in either improvements or retirements. In the intervening decade and a half the 4-4.5K hp locomotive has become the standard for road power much in the same way that 3K hp became the standard a generation earlier. Sizing a train for a 6K hp locomotive when only 4K hp is available becomes a dispatching headache. The 3K hp standard lasted about 25-30 years so eventually the horsepower war will heat up again. I would tend to agree. I think what might push it along is the continuing growth of intermodal traffic where higher HP per ton is generally the rule. A 6000 HP AC is a better fit than a 4400 HP AC six axle. If a good 6000 HP AC unit were available now, I'd bet BNSF would have gone for them rather than the 4400 HP A-1-A AC's they've recently purchased. Three 6000 HP ACs could replace four of the A-1-As on their transcon route without missing a beat. I seem to recall that both UP and CSX generally run(or ran) 6000HP locomotives in 2 unit sets. My understnding is that it is uncommon to run 18000HP AC traction consists on the head end of a train (can't that damage draft gear?) . The Chinese are supposedly running their new 6,000HP units in 3 unit sets on Mineral trains (maybe the Australians as well) but at lower speeds I don't see the advantage... Also, the BNSF philosophy on the ES44C4 seems to be for three A-1-A AC units to replace a like number of six axle DC motored 4400 HP units on fast freights (same number of units but fuel and maintenance costs are supposed to be reduced with same or better performance)..
oltmannd: D.Carleton: Very good comments all around. I would add one more piece. When the AC6000CW was introducing in December of 1995 the AC4400CW had been around for just over a year. Production AC transmission locomotives were a new reality on the railroads and they were still 'feeling their way' as to application and the upper limit of their power. The 6K hp offerings from GE and EMD had issues at the start and those have resulted in either improvements or retirements. In the intervening decade and a half the 4-4.5K hp locomotive has become the standard for road power much in the same way that 3K hp became the standard a generation earlier. Sizing a train for a 6K hp locomotive when only 4K hp is available becomes a dispatching headache. The 3K hp standard lasted about 25-30 years so eventually the horsepower war will heat up again. I would tend to agree. I think what might push it along is the continuing growth of intermodal traffic where higher HP per ton is generally the rule. A 6000 HP AC is a better fit than a 4400 HP AC six axle. If a good 6000 HP AC unit were available now, I'd bet BNSF would have gone for them rather than the 4400 HP A-1-A AC's they've recently purchased. Three 6000 HP ACs could replace four of the A-1-As on their transcon route without missing a beat.
Yes, three AC six axles can pull a knuckle on a regular freight or intemodal train pretty easily. You'd definitely have to train handling rules in place to restrict overall consist TE. Four Dash 9s can do the same, however.
My understanding of the A-1-As was they were a direct, one for one, replacement for six axle DC machines. After all, they have the same HP and same max TE. So if BNSF is replacing DC 3 for 4, they are also reducing the HP/ton on the transcon route. My understanding of the BNSF's operations was that the transcon route was predominantly HP driven - trains powered to the right HP/ton usually had lots of leftover max TE, hence DC machines for this route.
I believe what also 'messed up' the 6000 hp units (both AC6000CW and SD90MAC-H) was that both GE and EMD were playing catch up with Morrison-Knudsen. As you recall MK announced the 5000 hp MK5000C locomotive right after the AC4400CW and SD70MAC came out. Both companies were faced with a rush to produce a 6000 hp unit, both to be better than the MK5000c, and to be a hedge in case MK used the 16 cylinder Catepillar 3600 engine (good for at least 6000 HP). As a interime both companies come up with the 'upgradeable' models, with 4400hp now and 6000hp when the new prime movers comes out. EMD also offered the 20 cylinder 710 SD80MAC, which only Conrail went for (funny how these are still running while the SD90MAC-H are all gone). Unlike the 567, 645, 710, and FDL, which all underwent significant design work and testing before ever being put in production units, the 265H and HDL engines I believe were rushed out too soon, with the result that they railroads became disinchanted with the whole 6000hp concept.
Stuart
Why does the "rushed into production" explanation for the problems with the 265H and HDL sound somewhat familiar? Alco enthusiasts need not respond.
ATSF3463 I believe what also 'messed up' the 6000 hp units (both AC6000CW and SD90MAC-H) was that both GE and EMD were playing catch up with Morrison-Knudsen. As you recall MK announced the 5000 hp MK5000C locomotive right after the AC4400CW and SD70MAC came out. Both companies were faced with a rush to produce a 6000 hp unit, both to be better than the MK5000c, and to be a hedge in case MK used the 16 cylinder Catepillar 3600 engine (good for at least 6000 HP). As a interime both companies come up with the 'upgradeable' models, with 4400hp now and 6000hp when the new prime movers comes out. EMD also offered the 20 cylinder 710 SD80MAC, which only Conrail went for (funny how these are still running while the SD90MAC-H are all gone). Unlike the 567, 645, 710, and FDL, which all underwent significant design work and testing before ever being put in production units, the 265H and HDL engines I believe were rushed out too soon, with the result that they railroads became disinchanted with the whole 6000hp concept. Stuart
I don't know how you can play "catch up" with a program that itself was unsuccesful,given that MK Rail collapsed (although not primarly due to the MK5000C) well before most of GE & EMDs units hit the rails. MKs successor MPI decided not to pursue the new built road locomotive market (esp. when they became part of Wabtec, who are a major supplier of locomotive components to both GE and EMD)..
EMD was unable/unwilling to invest the resources into improving the 265H. GE product improved the HDL into the GEVO, which so far is a success in the market..
At the time that GM and GE embarked on the 6000hp development they didn't know that MK's MK5000C would be unsuccessful.
Development projects for locomotive are not short term undertakings....two to four years between the idea of a NEW product and the actual production of it. If a competitor announces they are doing something revolutionary....the competition cannot wait until the revolution is completed to find out if it is really a success or a failure....if it is a success and you don't have a competitive alternative...you have made your first step to going out of business.
Never too old to have a happy childhood!
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