MichaelSol wrote: JSGreen wrote:Well, since by your own admission, "but this is a hypothetical...", everything else is just a boilerplate. Find the real numbers, plug them in, and then the diccussion might be meaningful. Until then, its a great big game of What IF. Here's an Idea....What If we talk in general terms until we actually find some reasonable numbers?Just my Well, I just love "general terms" because anybody can say just about anything and it is meaningless. The hypothetical is based on something slightly better than just "thin air." The last motive power study that involved maintenance specifics that I participated in was 32 years ago, but my recollection is that the diesel engine constituted approximately 70% of the maintenance and repair requirements of an SD-40-2 locomotive, which is what we were looking at. Brakes and rigging were about 10% and "other electrical" about 10%. I don't specifically recall that the DC traction motors were a big item at all, but what's left is around 10%. If the economic advantage is solely in traction motor repair costs, the "break-even" on AC would require that the DC traction motors cost approximately 93% of total locomotive maintenance and repair costs. That's not reasonable.
JSGreen wrote:Well, since by your own admission, "but this is a hypothetical...", everything else is just a boilerplate. Find the real numbers, plug them in, and then the diccussion might be meaningful. Until then, its a great big game of What IF. Here's an Idea....What If we talk in general terms until we actually find some reasonable numbers?Just my
Well, I just love "general terms" because anybody can say just about anything and it is meaningless. The hypothetical is based on something slightly better than just "thin air."
The last motive power study that involved maintenance specifics that I participated in was 32 years ago, but my recollection is that the diesel engine constituted approximately 70% of the maintenance and repair requirements of an SD-40-2 locomotive, which is what we were looking at. Brakes and rigging were about 10% and "other electrical" about 10%. I don't specifically recall that the DC traction motors were a big item at all, but what's left is around 10%.
If the economic advantage is solely in traction motor repair costs, the "break-even" on AC would require that the DC traction motors cost approximately 93% of total locomotive maintenance and repair costs.
That's not reasonable.
My recollection from the early 90s was that traction motor cost was about 1/3 of the total maintenance and overhaul cost for a typical DC locomotive. It varied from road to road depending on operating circumstances from a low of about 25% to roughly 50%.
It is rare for a DC road locomotive to make it to it's first power assembly change out (about 4-5 years) with more than about half if it's original motors still under it. As I recall, the Conrail SD80MACs still had all their original motors under them 3 years in. Might have had one or two invertors changed out.
The work done by the AAR ad-hoc committee that was writing a spec for a 5000 HP AC locomotive took actual costs from the various participating RRs and figured that motor cost savings alone didn't justify the premium cost - you had to also get some significant replacement ratio vis a vis the typcial new DC units of the day.
The goal of the commitee was to spec out an an purchase a test fleet to gain some real world experience. When BN placed their huge order for SD70MACs the point was moot and the committee disbanded.
-Don (Random stuff, mostly about trains - what else? http://blerfblog.blogspot.com/)
GP40,
What position do hold with CSX?
What insider information is CSX telling you that they are not telling me? I'm pretty well plugged into the CSX grapvine.
Why do you assume my statement of costs are not correct? I'm relying on published costs. You're assuming a backdoor deal was made, but you can't prove it.
Nick
Take a Ride on the Reading with the: Reading Company Technical & Historical Society http://www.readingrailroad.org/
After having read the neat article in the Nov. Trains about CSX's deployment of "heavy" locomotives plus some comments in this thread, few things come to mind.
CSX certainly has some spots where TE rules the day and I can see why they'd want some of those "heavies". But, CSX has quite a bit of flat land, high speed territory (NJ to Chicago and Alexandria to FL come to mind) where AC units would be an extravigance. CSX could theoretically play the BNSF's game of a segregated fleet to it's advantage, but they'd really have to take a more disciplined approach to motive power assignment.
I haven't seen anything ever happen on CSX that approaches that level of discipline. CSX is notorious for not being able to get it's good ideas fleshed out and implemented.
Regardless of the price you pay for AC vs DC units, once you have them in the fleet, that is a sunk cost and your focus should be on maximizing their productivity in terms of HP and TE and minimized fuel costs. In most cases when you have a mixed fleet, that will imply segregating them matching routes, schedules and traffic to locomotive type.
The CSX article had no mention of any track force or ride quality testing of those "heavies" at 70 mph. Since CSX is using them on vans, too, I wonder what the impact (pun intended) of those "heavies" is on the track structure or crew person's butt at speed.
I suspect that "GP40-2" is telling us that CSXT's locomotive-acquisition decisions are typically made in response to proposals from the manufacturers. Basically the manufacturers decide what features they can--or cannot--offer; and, in response to the proposals, CSXT decides what financial arrangements it can--or cannot--make to obtain the features that it needs and that the manufacturers can provide. In other words, everything is subject to some degree of negotiation.
Jay Potter
oltmannd wrote: CSX certainly has some spots where TE rules the day and I can see why they'd want some of those "heavies". But, CSX has quite a bit of flat land, high speed territory. . .where AC units would be an extravigance. CSX could theoretically play the BNSF's game of a segregated fleet to it's advantage, but they'd really have to take a more disciplined approach to motive power assignment. I haven't seen anything ever happen on CSX that approaches that level of discipline. CSX is notorious for not being able to get it's good ideas fleshed out and implemented.
CSX certainly has some spots where TE rules the day and I can see why they'd want some of those "heavies". But, CSX has quite a bit of flat land, high speed territory. . .where AC units would be an extravigance. CSX could theoretically play the BNSF's game of a segregated fleet to it's advantage, but they'd really have to take a more disciplined approach to motive power assignment.
Most recently, CSXT's "more disciplined approach" involved (1) resolving GE and EMD software incompatibilities so that mixed consists of AC4400CWs and SD70MAC/MAC-T1s could be used in low-speed coal loading and then (2) acquiring ES44DCs, which enabled increasing numbers of SD70MAC-T1s to be assigned to coal service.
oltmannd wrote: The CSX article had no mention of any track force or ride quality testing of those "heavies" at 70 mph. Since CSX is using them on vans, too, I wonder what the impact (pun intended) of those "heavies" is on the track structure or crew person's butt at speed.
CSXT considered both ride quality and impact on track structure. The former is more a function of truck design than unit weight; and the latter is more a function of the high levels of tractive effort that can be produced at low speeds than a function of unit weight alone.
JayPotter wrote: oltmannd wrote: CSX certainly has some spots where TE rules the day and I can see why they'd want some of those "heavies". But, CSX has quite a bit of flat land, high speed territory. . .where AC units would be an extravigance. CSX could theoretically play the BNSF's game of a segregated fleet to it's advantage, but they'd really have to take a more disciplined approach to motive power assignment. I haven't seen anything ever happen on CSX that approaches that level of discipline. CSX is notorious for not being able to get it's good ideas fleshed out and implemented. Most recently, CSXT's "more disciplined approach" involved (1) resolving GE and EMD software incompatibilities so that mixed consists of AC4400CWs and SD70MAC/MAC-T1s could be used in low-speed coal loading and then (2) acquiring ES44DCs, which enabled increasing numbers of SD70MAC-T1s to be assigned to coal service. Jay Potter
I hope they can keep the assignements straight. It's pretty disheartening to see ACs mixed with Dash 2 on vans and those "dog's breakfast" locomotive consists roaming around all over. It makes for interesting railfanning, but it's kind of depressing from a professional's point of view. They're nothing better than seeing locomotives doing exactly what they were built to do.
JayPotter wrote: oltmannd wrote: The CSX article had no mention of any track force or ride quality testing of those "heavies" at 70 mph. Since CSX is using them on vans, too, I wonder what the impact (pun intended) of those "heavies" is on the track structure or crew person's butt at speed. CSXT considered both ride quality and impact on track structure. The former is more a function of truck design than unit weight; and the latter is more a function of the high levels of tractive effort that can be produced at low speeds than a function of unit weight alone. Jay Potter
EMD's HTC's weren't particularly wonderful at 70 mph under 390,000# locomotives. I can't imagine GE's version is much better. What does GE do for primary lateral suspension on their Hi-adhesion truck?
In general, what makes for a good ride (stiff primaries, soft secondaries) makes for lousy adhesion.
Perhaps it's a bit of the down side of Diesels not having "home bases." Steamers rarely freely roamed the system. Even for long distance trains, the locomotives were often changed at certain points. And each locomotive had a home - to which it would regularly return. Thus a locomotive best suited to the mountains would rarely be seen on the flatlands, etc, and so on.
Today it's not at all unusual to see run-through power hundreds of miles from it's home rails - something you would never have seen in steam days.
Larry Resident Microferroequinologist (at least at my house) Everyone goes home; Safety begins with you My Opinion. Standard Disclaimers Apply. No Expiration Date Come ride the rails with me! There's one thing about humility - the moment you think you've got it, you've lost it...
oltmannd wrote: What does GE do for primary lateral suspension on their Hi-adhesion truck?
What does GE do for primary lateral suspension on their Hi-adhesion truck?
Like most specific design issues, that's way beyond my level of understanding. However the GE truck at issue is the Generation I steerable truck, not the HiAd truck.
oltmannd wrote: It's pretty disheartening to see ACs mixed with Dash 2 on vans.
It's pretty disheartening to see ACs mixed with Dash 2 on vans.
CSXT does sometimes augment its two-unit AC-traction consists with a single DC-traction unit; however I think that practice will occur less frequently in the future than it has in the past.
JayPotter wrote: oltmannd wrote: What does GE do for primary lateral suspension on their Hi-adhesion truck? Like most specific design issues, that's way beyond my level of understanding. However the GE truck at issue is the Generation I steerable truck, not the HiAd truck. Jay Potter
I see the ACs get the radials but the ES44DC get the Hi-ad. Is the radial not available with DC motors?
oltmannd wrote: I see the ACs get the radials but the ES44DC get the Hi-ad. Is the radial not available with DC motors?
The ES44DC is not available with steerable trucks. I don't know whether the SD70M-2 is available with radial trucks. I have the impression that it is not; but I don't recall how I got that impression.
CSX's power policy is first in first out. Although we try to keep the power in cycle ie Q406 power goes to Q405, Q301 power goes to Q300, ect. If the cycle power is not avalable, we will use the first avalable power set that is consistant with the need of the train, ie Train Control/Cab Signal equipped, and approprate tonnage ratings, etc.
We will not miss an orgination because the cycle power is not avalable, if there is non-cycle power on terminal to make the orginination. That's why you sometimes see dogs on the van trains, and two brandnew units on the poop trains.
JayPotter wrote: oltmannd wrote: I see the ACs get the radials but the ES44DC get the Hi-ad. Is the radial not available with DC motors? The ES44DC is not available with steerable trucks. I don't know whether the SD70M-2 is available with radial trucks. I have the impression that it is not; but I don't recall how I got that impression. Jay Potter
SD70M-2s come with the radial truck (HTR)
nbrodar wrote: CSX's power policy is first in first out. Although we try to keep the power in cycle ie Q406 power goes to Q405, Q301 power goes to Q300, ect. If the cycle power is not avalable, we will use the first avalable power set that is consistant with the need of the train, ie Train Control/Cab Signal equipped, and approprate tonnage ratings, etc. We will not miss an orgination because the cycle power is not avalable, if there is non-cycle power on terminal to make the orginination. That's why you sometimes see dogs on the van trains, and two brandnew units on the poop trains. Nick
"Sometimes" down here on the Abbeville Sub is "nearly always"!
Jay:I want to commend you on an excellent article. I have enjoyed your contributions to Trains for years. I believe you covered Alco's in WV/Ohio quite extensively in the past. If not, it is my failing memory in play here.
A few questions if you dont mind...
1. Dont know much about what makes trains run, but your article has intrigued me. What exactly is tractive effort and what does it measure? I somehow am thinking it has something to do with the weight of the locomotive * adhesive rate (400,000 lbs * 35% = 140,000) but that seems low. If a unit has 200,000 pounds of tractive effort, what does that mean when lugging a 17000 ton train?
2. What is torque and how does it apply to this discussion? I assume torque is circular energy or motion.
3. When thinking about what you read about extra weight, I recall the old days at home with a pickup truck and snow/icy conditions. We would add extra bags of ballast (salt, rocks, etc) over the axle to improve traction. Same principal here?
4. I get the impression that low speed operations with heavy locomotives are rough on rail. Is that correct?
Any suggested readings on this subject for a nonmechanical railfan?
ed
MP173 wrote:Jay:I want to commend you on an excellent article. I have enjoyed your contributions to Trains for years. I believe you covered Alco's in WV/Ohio quite extensively in the past. If not, it is my failing memory in play here. A few questions if you dont mind... 1. Dont know much about what makes trains run, but your article has intrigued me. What exactly is tractive effort and what does it measure? I somehow am thinking it has something to do with the weight of the locomotive * adhesive rate (400,000 lbs * 35% = 140,000) but that seems low. If a unit has 200,000 pounds of tractive effort, what does that mean when lugging a 17000 ton train?
I'm not Jay but let me try answering some of the questions, Tractive Effort is a pulling force parallel to the rails generated by the torque of the traction motors, multiplied by the motor gearing, and the leverage of the wheel radius. Most locomotives have a standard gearing and wheel size so the manufacturers quote standardized figures. This is a potential figure, the actual amount may be less. The locomotives wheelslip system allows the locomotive to convert a stated proportion of the locomotives weight into Tractive Effort. If the locomotive has a factor of adhesion of 35% and the locomotive weighs 400,000 lbs. then the maximum T.E. of the locomotive is 400,000 X .35 = 140,000 lbs. If this amount is less than the potential T.E. produced by the motors you have a slippery locomotive. Since the motors on a AC4400CW can produce 200,000 lbs. and the "dispatchable" factor of adhesion (available under bad conditions) was 35% (.35) you turn the equation around 200,000 / .35 = the desireable weight of the locomotive. Of course building a locomotive this heavy is impractical so you just make it as heavy as your infrastructure will allow. The wheelslip system will limit the actual T.E. to minimize wheelslip. For a discussion of the effects of horsepower and T.E. on moving a train, I defer to an expert Al Krug see the relevent page of his website here
Al Krug's Hp vs TE page
Same principle, although it also works on dry rail, as well as wet icy, rail.
4. I get the impression that low speed operations with heavy locomotives are rough on rail. Is that correct? Any suggested readings on this subject for a nonmechanical railfan? ed
MP173 wrote: A few questions if you dont mind... ed
I'm grateful to John Beaulieu for referring Ed to Al Krug's web site and saving me from having to reveal vast gaps in my knowledge. And even what I do know is explained better there than I could explain it.
But I do need to respond to Ed's question about the extent to which "low speed operations with heavy locomotives are rough on rail", because I don't want to risk leaving the impression that CSXT pursued its heavy locomotive program with no regard to track structure. So I'll mention a couple of points.
With regard to the metal-to-metal contact of wheels on rails, the wheels will wear more quickly than the rails will wear.
The primary track-structure problem relates to the magnitude of the lateral forces that are generated when trains are moved through curves.
Ed, if you look in the article at note 2 in the table on page 44, you'll see a reference to four-unit SD50 consists that were withdrawn from Mountain Subdivision helper service because they generated excessive forces. What basically happened was that those consists produced tractive-effort levels high enough to move trains that were so heavy that their movement produced lateral forces against the rails of sufficient magnitude to break the fasteners (Pandrol e-clips) that affixed the rails to the ties. The trains currently being moved by today's two-unit heavy locomotive consists do not generate forces of that magnitude, even on the Mountain Subdivision.
CSXT's purpose in having locomotives that can produce 200,000 pounds of tractive effort is to prevent trains from stalling. In other words, these locomotives will very seldom actually produce anywhere near that magnitude of tractive effort, even on the Mountain Subdivision. For example, in a typical Mountain Subdivision test the helper locomotives being tested will not produce their maximum possible tractive efforts unless there is a power reduction in the head-end consist. This is because the trains generally move without either of the two consists being required to produce the maximum amount of tractive effort that it is capable of producing.
In summary, at speeds below 10-or-so miles-per-hour under a given set of rail conditions, a "heavy" locomotive with a 200,000-pound software-imposed cap on tractive effort will produce a higher level of tractive effort than a counterpart standard locomotive would produce under those rail conditions; however that tractive effort will almost never reach 200,000 pounds. Typically the tractive effort being produced by the heavy locomotive will be no greater than the tractive effort that a standard locomotive would have produced if rail conditions had been better.
I read Al Krug's excellent essay on TE and horsepower. In fact I read it twice. Good material. While I wont say that I now am an expert on locomotives, tonnage, grades, etc., the essay certainly helped me understand the basics of railroading.
Anyone else out there that doesnt understand this should take a little time (30 minutes) and read Al's explanation. He has an excellent website.
Jay, I will go back and read your article again, with just a bit of knowledge about the subject.
MP173 wrote:Jay, a couple of questions regarding the CSX line east of Grafton. I would guess the predominent traffic on the line is coal. How many trains does that line see a day? I note that the tower at Rowlesburg was still in operation. Is it still open? What is the purpose of the tower? Controlling switches for the helpers? How many other towers are in operation on that line?
Mountain Subdivision traffic consists of coal and one daily manifest in each direction. Coal traffic levels vary. Rowlesburg and West Keyser towers are still open. They control various nearby switches and monitor the passage of main-track traffic. Head-end power for the manifests can be either AC-traction or DC-traction units. Head-end power for tonnage trains is exclusively AC-traction, either "heavy" or standard-weight units with either rigid or steerable/radial trucks. The helper is a two-unit consist of class CW44AH units. These are "heavy" AC4400CWs with steerable trucks and GE's HTE software, which allows each traction motor to produce a maximum of 36,000 pounds of tractive effort.
MP173 wrote:I did check it out... a bit too complex for me at this time, but heck, by tomorrow I should at least understand some of it.Actually, this has been pretty enlightening. I always thought HP was critical.So, what happens when you mix AC and DC? Lets say you got some AC units in which you are down to 5mph on a grade. Do the motors in the DC units burn up? Or is that even an issue...do they segregate the units?ed
Yup. You burn up the motors in the DC unit. It's a big issue. It's why you see BNSF segregate their fleets. It's what CSX seems to struggle with - but it's not easy to do, particularly when you're short on power.
When Conrail first got the SD80MACs, they rule was, "never mix (but if you do, the DC unit leads)". Apparently, there is no "never" on the RR.
Zapp wrote
... Sitting in the engineer's seat you can really feel that horsepower being applied to the rails in AC. Those things will vibrate your brains out!!!!
Sitting in the engineer's seat you can really feel that horsepower being applied to the rails in AC. Those things will vibrate your brains out!!!!
In a sitting position, is this anatomically correct?
Regards,
Yes it is.
It's funny you can feel it on the engineers side, but if I'm on the other side I can't feel nothing.
Our community is FREE to join. To participate you must either login or register for an account.