No reason 611 couldn't run up to 60mph. As I understand it the 40mph speed limit was a reaction (knee-jerk or otherwise) to the 1986 Dismal Swamp wreck, even though the speed and train handling had nothing to do with the wreck, one of the passenger cars "picked" a switch. I imagine insurance coverage may have had something to do with the speed limit as well.
On the other hand, two reasons I can think of to limit the speed to 40mph would be to save wear and tear on the locomotive, and because riders want the ride to last.
Well thanks for that information Lois! I don't understand the non-interest in wrecks, there's always something to be learned from wreck stories, especially the "why's-and-wherefores" and how you keep them from happening again.
Thanks again!
The formulae are for indicated horsepower, ihp, and as you might suspect you can get more 'exact' data by integrating the result from a physical steam-engine indicator card, first for one 'side' of the cylinder, then for the 'other'. Usually, however, ihp is much higher than drawbar horsepower, dbhp, which ought to be an 'actual' number measured by a dynamometer car or test plant, net of all machine losses. Aren't there indicator cards extant for a number of J tests?
Note that one 'ringer' in the formulae is an assumption for boiler-pressure drop. If a locomotive has steam-chest pressure gauges (as I believe 611 does) you would use these readings as the 'pressure' input for the duration of admission
There are two reasons why steam condenses in the cylinders. One is partially avoidable, the other an inevitable consequence of work being extracted from the steam (to move the locomotive and train).
The first is commonly called 'wall condensation' and it occurs when water molecules in the steam preferentially adhere to the exposed surfaces of the cylnder, heads, and piston/rod. If the temperature of the inner cylinder wall is lower than that of the steam -- which is usually the case -- the steam may preferentially condense onto it; there is also a physical 'wetting' effect. Both cause an effective phase change and concomitant volume decrease, and this relieves some of the effective piston thrust. One way to get around this is to heat the 'cold' surfaces, which limits the range of thermal cycling at the walls; another is, as noted, to use higher superheat in the steam to keep its critical temperature above the condensation point even at high admission pressure. Theoretically if you heat the wall metal above the critical temperature, little or no steam will actually change phase during expansion -- this was the point of Chapelon's passing all the main steam to the HP cylinders through the HP jacketing before admission.
The second, unavoidable form of loss is nucleate condensation. As expansion progresses, and work is done on the piston, the steam loses energy. When small volumes reach the critical point, they can condense on nuclei -- of oil, of water droplets, of dust from boiler carryover, it doesn't really matter -- and the phase change as described above occurs, except now throughout the volume of the steam.
Superheat is the great help for this situation, and the reason for the 'dramatic' gains seen in superheated engine operation as long expansions/short cutoffs come to be practically used.
But there is a flip side, which is that when release starts to take place, the 'nucleate steam' (now partly water vapor, partly droplet nuclei, like fog) begins promptly to flash back to higher effective volume, right at the time you don't want it expanding. That is a reason exhaust tracting needs to be specially designed for higher and higher volume if back-pressure issues on the released steam are to be avoided. Any remaining superheat in the steam after release is actually something of a bad thing, unless you make special arrangements to use that energy effectively in the locomotive front end to provide draft, or have a high-volume tract for exhaust steam going to auxiliaries, an exhaust-steam injector, etc.
I will concede that the J appears to have been an excellent performer. I also get the impression that it falls into the same category as NYC's Niagaras, it was too big and too powerful for the service in which it was actually used.
The Niagra was not more than what was required. As the Central lost passenger business, they combined trains. So their trains remained pretty long. The PRR did the same, and their equivalent was the T-1. A Hudson might be able to take 14 or 16 cars Harmon - Buffalo, but a Niagra 22 or 24. Did you ever see a single E-unit on a Harmon - Buffalo passenger train? Three were normal, and a Niagra could do the work of three!
A 16 car train would leave GCT behind a T or P motor. At Harmon, the Niagra would back down on the train with six or eight mail and express cars that had come up the West Side. The Century, of course, was an exception. A Hudson could have handled the passenger train, but the added cars required the Niagra (or a Mowhawk at possibly a bit less speed).
Regarding the J's, their performance was put to use on some of the through Southern trains that could be pretty long, again with a lot of mail and express.
There almost certainly were some long troop trains duringWWII coupled behined both N&W J's and Niagras.
friend611And even then, I'm sure the J's were not asked to pull the 25-plus car excursion trains that 611 handled in the 80s and 90s. I'm sure Bob Claytor had a clear picture of her abilities, or he would not have allowed her to run such large trains. And I'm certain these large excursion trains taxed her abilities on a few occasions, though mostly she tended to handle them quite easily. However, on Saluda Grade, with three diesels that were mostly for dynamic braking though they could be used for assistance if necessary, according to the book "Steam's Camelot" it was feared with the HP of 611 and the diesels, the effort required to pull the train up the steep grade might result in drawbars and couplers being pulled out of passenger cars. So, it was decided to pull most of the train up the grade behind the diesels and leave the last four or five cars for 611 to handle. In the book, the diesel units were SD40-2's with 9,000 combined HP, or estimated 3,000 HP per unit. 611 was rated at an estimated 5,100 HP, possibly up to 5,400 HP as stated previously. This meant a total of 14,100-14,400 HP tugging on 20 passenger cars, the majority of which were 85-foot streamlined coaches. This was on a grade ranging from 4.5 to as much as 5.1 %. With these figures, it is easy to understand the concern about the drawbars and couplers on the passenger cars. Now what these figures mean and what could have happened I will leave for Overmod, Juniatha and other like minded persons to tackle. lois
A few things to consider about this post:
The J, like any other steam engine produces its maximum power at a specific speed. For the J, that was probably around 40 mph or so. They weren't making 40 mph up that grade. At the single digit speeds the J was capable of with 5 cars, it was lucky to be making 900 - 1000 hp. Also, if I recall correctly, (could be wrong) during those trips the 611 was set at 275 psi so its max TE would be around 73,000 lbs. Which is not a bad thing since running it at 275 psi would actually improve its adhesion. Lastly, what type of coal were they using? Unless they were using good quality #14 or #8 coal, that would also cut performance. I know Ross was complaining during the 614 Chessie trips that it was getting harder and more expensive to find the proper coal for the 614.
Can they even get Pocahontas coal today? Most of the mines in that region were being shut down back in the early 1980's. Even up in the larger Pittsburgh Field in Northern WV - SW PA, with similar coal, they are running out. Many of the mines are shut down, and the mines that are left open are using longwall mining. They are removing a tremendous amount of coal per year, most of it going to China, and the last I heard is they will be mined out in less than 20 years at this rate. The rest of the coal isn't worth mining - too high in sulfur and impurities. It is going to be increasingly hard and expensive to find good steam coal to run these engines in the near future.
friend611According to an article published in Trains magazine in 1994 about the Pocahontas Division of NS, coal was alive and well and NS kept busy in that region. There may not be as many mines as there were years ago, but as I personally observed during a visit to WV in 2011, there has been no real effect on coal operations. As regards to coal running out, I have personally seen places where seams of coal lie in the rocks along roads. The coal is there; it just needs to be discovered. Believe me, they would not consider running 611 if there was a lack of coal to fire her on. lois
1994 was 20 years ago. I grew up in the coal fields, and a lot has changed in the past 20 years, most of it not for the good. Between decreasing supply of high quality coal, increasing environmental laws and costs, coal mining in the east is a declining industry. Consol just shut down or unloaded a lot of their mines. They are focusing on natural gas now.
There is nothing to discover in the coal fields. They know exactly where all the coal is. The issue is all the best and easy to get to coal has been mined out. What is left, for the most part is either too expensive to get to, or low quality (high in sulfur and impurities).
There will always be some coal around in the east. The question for the future will be how much it will cost per ton, and is it good enough quality to burn in steam locomotives that were designed for a certain type of coal. Burning poor quality coal in a locomotive will decrease performance, increase maintenance costs, and more than likely cause the EPA to take notice. All it would take is one "executive" order from the EPA calling for steam to meet higher pollution standards, and you will see every restored locomotive off the tracks.
GP40-2Can they even get Pocahontas coal today?
In the quantities required for fantrips, yes.
A little more involved: the coal ought to be washed and sized to about 2", which involves some extra work not easily handled in 'truckload lots' delivered to the tender by loader. But the required equipment would not be difficult to construct, and could be made portable.
It's also possible -- in this particular kind of application -- to use the range of 'clean coal' fuel fabrication techniques to make a few tender-loads' worth of fuel. That might include SRC to remove the sulfur and ashing constituents, or cofiring with dolomite or torrefied-wood additives.
Fuel cost (as a percentage of overall trip costs) is probably no more for a 611 excursion than the 5% or so that it was for 8055 in Europe (where coal is more expensive to source). So the absolute economic 'advantage' of mine-run coal delivered in a heap where it can be trackhoe'd up into the tender may be far less, indeed outweighed, by the operating advantages of good fuel properly provided... just as it was in 1950.
Have we succeeded in locating a hp-speed curve for 611 including the steam-chest pressures available (at 300psi nominal) for each speed at the demanded load? I don't have good data to do anything other than the averaged formula (e.g. Davis equation with assumptions) that has already been done.
My assumption is that the diesels would be worked just to the point where 611 was at maximal effort, to give the best steam show. If that were being done today, a significant part of the diesel power would be applied via DPU to the rear (separating SD40s would probably have implied an extra crew at the time, particularly if the Southern pilot wasn't riding 611). That would put the 'node' somewhere in the train, probably not moving more than a few cars whether 611 was slipping or not.
The principal difficulty, of course, is that 611 can't put anywhere near the significant hp she could develop at, say 15 mph to the rail without slipping, particularly at her very low effective FA. So whatever concern there would be would involve rapid changes of TE for the consist as a whole, perhaps the result of a slight slack run-in at the slip (the diesels being delayed in loading down) followed by a relatively quick acceleration (with the diesels loading and 611 recovering adhesion). This was surely back in the days when the consist was not all-tightlock coupled, and it would be the non-tightlock cars that I'd expect to show the worst effects...
Overmod Have we succeeded in locating a hp-speed curve for 611 including the steam-chest pressures available (at 300psi nominal) for each speed at the demanded load? I don't have good data to do anything other than the averaged formula (e.g. Davis equation with assumptions) that has already been done. My assumption is that the diesels would be worked just to the point where 611 was at maximal effort, to give the best steam show. If that were being done today, a significant part of the diesel power would be applied via DPU to the rear (separating SD40s would probably have implied an extra crew at the time, particularly if the Southern pilot wasn't riding 611). That would put the 'node' somewhere in the train, probably not moving more than a few cars whether 611 was slipping or not. The principal difficulty, of course, is that 611 can't put anywhere near the significant hp she could develop at, say 15 mph to the rail without slipping, particularly at her very low effective FA. So whatever concern there would be would involve rapid changes of TE for the consist as a whole, perhaps the result of a slight slack run-in at the slip (the diesels being delayed in loading down) followed by a relatively quick acceleration (with the diesels loading and 611 recovering adhesion). This was surely back in the days when the consist was not all-tightlock coupled, and it would be the non-tightlock cars that I'd expect to show the worst effects...
Easier solution in 2014. Use one heavy weight ES44AC with high adhesion - high TE software to drag the entire train , 611 included over the grade. Simple.
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