Engines go to the scrapers with the same tonnage rating that they had the day the left the builders shop.
henry6 MP173: Do locomotives lose efficiency over time? In other words, at a certain time (new or after major overhaul) if a locomotive is rated at "x", will it lose that efficiency over a period of time? Ed Yes. But as Balt points out it at least takes a while before the timetables catch up.
MP173: Do locomotives lose efficiency over time? In other words, at a certain time (new or after major overhaul) if a locomotive is rated at "x", will it lose that efficiency over a period of time? Ed
Do locomotives lose efficiency over time?
In other words, at a certain time (new or after major overhaul) if a locomotive is rated at "x", will it lose that efficiency over a period of time?
Ed
Yes. But as Balt points out it at least takes a while before the timetables catch up.
Never too old to have a happy childhood!
MP173 Do locomotives lose efficiency over time? In other words, at a certain time (new or after major overhaul) if a locomotive is rated at "x", will it lose that efficiency over a period of time? Ed
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While they may....it will NEVER be reflected in the published tonnage ratings.
Somewhere here on another thread within the past year or so Railway Man had an explanation and commentary on tonnage ratings and how power was assigned during his experience. I won't attempt to recall and repeat it here - but it would be worth seaching for.
My understanding is that the Tonnage Ratings are based only on expected Tractive Effort from the locomotive class, at the assumed standard rail adhesion - is that correct ? In contrast, the Tonnage Rating is not based on HorsePower, which is more for speed considerations (as in HP/ ton - see the other current thread for that).
Further, the Tonnage Rating is based on the lower "continuous" rating of the current through the motors (to prevent them from damage) if the grade is long enough or if the train is anticipated to be slow enough to be there long enough to invoke it; otherwise, a higher "short-term" motor rating might be used instead as the basis for the Tonnage Rating.
Also, the Tonnage Rating is based on the train being on the Ruling Grade at the time, which presumes that the Ruling Grade is long enough to fully engage the expected 'normal' train*, and that there aren't any shorter "momentum grades" involved. (*That's one part of the definition of Ruling Grade.)
Anything else to add to this ?
- Paul North.
Yes, UP says an ES44AC engines is worth 12.1 equivalent axles-- but they rate a DC SD70 at 10.4 axles. Don't bother trying to figure out why they use that terminology; in the end, each engine has tonnage ratings for each of UP's hills.
An ES44 on a coal train is alleged to be able to manage 6500 tons east from the Powder River mines; the climb from Lost Springs includes four miles of nearly continuous 1%, so no one would be astonished if they didn't make it. Anyone know what a typical train there actually has?
CShaveRR In The Railroad--What It Is, What It does, John Armstrong said that trains would be sent out at times slightly in excess of the tonnage ratings of their power, and they would just hope that they could make it (of course, I read this in the book's first edition--that was four editions ago, and may have bee adjusted since then). In my job with the railroad, I didn't have to worry about powering the trains we classified for. I recall that underpowering was often an issue back in CNW days, just because we never had enough. Getting all of those widenose GEs toward the end of the line helped a lot. UP used to have a standard horsepower-per-ton figure for each type of train. They've since gone to tons-per-equivalent-powered-axle (so when's an axle not an axle?). This is supposed to be more accurate than hp/t, and more efficient, though I saw evidence of complaints soon after that system was instituted. I don't recall ever seeing tonnage ratings covering specific subdivisions for each locomotive model on UP--Heaven knows they have some grade variants around the system! Wonder whether Jeff can offer some insight...
In The Railroad--What It Is, What It does, John Armstrong said that trains would be sent out at times slightly in excess of the tonnage ratings of their power, and they would just hope that they could make it (of course, I read this in the book's first edition--that was four editions ago, and may have bee adjusted since then).
In my job with the railroad, I didn't have to worry about powering the trains we classified for. I recall that underpowering was often an issue back in CNW days, just because we never had enough. Getting all of those widenose GEs toward the end of the line helped a lot.
UP used to have a standard horsepower-per-ton figure for each type of train. They've since gone to tons-per-equivalent-powered-axle (so when's an axle not an axle?). This is supposed to be more accurate than hp/t, and more efficient, though I saw evidence of complaints soon after that system was instituted.
I don't recall ever seeing tonnage ratings covering specific subdivisions for each locomotive model on UP--Heaven knows they have some grade variants around the system! Wonder whether Jeff can offer some insight...
Isn't the "tons-per-equivalent-powered-axle " rating a way to differentiate between AC and DC motored power? I.E AC traction locomotives count as more than 6 axles in figuring the power rating?
"I Often Dream of Trains"-From the Album of the Same Name by Robyn Hitchcock
The following is a tonnage rating table for a inter-divisional train that proceeds over multiple crew districts and operating divisions...
ARRE TIME MILE SD40 SD50 C408 ES4D S70A C44A C44AHPoint1 0120 0084 5800 6900 7500 8100 9550 10150 11000 Point2 1000 0203 5800 6900 7500 8100 9550 10150 11000 Point3 2000 0172 5400 6400 7000 7550 8900 9450 10250 Point4 0545 0125 5150 6100 6650 7200 8450 9000 9750 Point5 1655 0149 4350 5150 5650 6050 7150 7600 8250 Point6 0345 0182 2800 3300 3600 3900 4600 4900 5300 Point7 1345 0142 5000 5950 6500 7000 8250 8750 9500
As can be seen, different territories have different ratings. If the intent is to run the train from origin to destination without changing either train consist or locomotives enroute then power has to be assigned in accordance with the requirements of the lowest rated 'Point6' territory. A 6000 ton train can easily be handled with 2 SD40's over all territories except the Point6 territory; additional power must be added to handle the train for the entire route. Adding or removing power from a existing train will generally result in approximately one hour delay; that presumes that additional power was actually available and waiting when the train arrives at the start of the Point6 territory.
In the days of CR, MILW & RI and their deferred maintenance of everything...it was common to use 6 engines on a train that required 3 in the hopes that at least 3 of the 6 would get the train to destination....Today's Class I carriers DO NOT operate in that manner; they expect a locomotive that is rated for 5000 tons on a territory to handle that 5000 tons as long as the locomotive is operating normally. If enroute defects reduce the tonnage capability of the locomotive then suitable remedies will be formulated to get the train to destination; it is not unheard of for a train to be delayed 8 - 12 - 24 hours or more while efforts are made to get additional power to a train that has had engine failure on line of road. Most trains operating need all the working engines in their consist to complete their run.
Locomotives, besides right of way investment, are the largest Capital Investment that the carriers make - they expect the utilization of this investment to run and return profits to the company. Unnecessarily overpowering trains is wasting that capital investment and reduces that amount of $$$ that goes to the bottom line.
Usually freight railroads will publish tonnage ratings per locomotive or per unit lash ups for given segments of it route and by direction. Some will give ratings for certain cargoes, cars, train make ups, weather (temperature and precipitation) conditions. But while these are written rules, there always is the rule of thumb and the rule of immediate predicament that may over rule that which is written.
CShaveRRI don't recall ever seeing tonnage ratings covering specific subdivisions for each locomotive model on UP
Carl
Railroader Emeritus (practiced railroading for 46 years--and in 2010 I finally got it right!)
CAACSCOCOM--I don't want to behave improperly, so I just won't behave at all. (SM)
No one should imagine that "tonnage ratings" are carefully worked out, and that if an SD40-2 is rated at 1015 tons from point A to point B then you can count on it making the grade with 1014 tons. The odds of it being successful may be 98%, but more likely they will be 90%, or 80%, and they might be 50% or less. On most railroads "tonnage ratings" are just for show, and dispatchers use their own experience to assign power.
In as much as this is the world I work in day in and day out....what you are getting from me is what REALLY happens....good, bad or ugly....them is the facts Jack!
Balt, the question was hypothetical. The locomotive could be a Lionel or EMD or whatever. The tonnage rating was X and the train tonnage was X-15 or whatever. No, power dispatchers and computers don't take crew and skill into account. But railroaders do.
First off I would hate to see the territory where a SD40 is only rated for 1015 tons.
Secondly the locomotive utilization people believe they have done their job properly when they assign the locomotive rated for 1015 tons to the train that is 1014 tons. The answer you get when you say that it is too close to the rating is....It's not over the rating so run the train.
Power utilization people don't care who is operating the throttle, sanders and brakes...all they care about is that the engine is rated to a number and that number is equal to or greater than the tonnage of the train.
Local field operations people may want more power on the train, but unless they actually have control of the power assignments (and most don't) the train will be operated with the power assigned and local field opeations will have to deal with the outcome - good or bad. If the outcome is bad, local field operations will have to either find another train to shove, doublehead or give up power to get the stalled train moving. If no other trains are available for assistance then the stalled train will have to double the train up the grade it stalled on.
Yes. Seriiously, yes. Depends on power availability, needs, crew's acumen and skills, type of cars, type and age and condiition of locomotives, weather conditions, return needs. So they might or might not.
If a train ws at or very near the tonnge rating of a locomotive (for exampe: An SD40 is rated at 1015 tons for the territory and the train weighs 1010 tons) would the railroad assighn an additionl engine to ensure that it could pull the train over the route or would they take their chances?
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