Firelock 76
In a nutshell: you can never save as much as you can earn by running the right trains to the right destinations at the right time – carrying the sort of freight that earns a living for the railroad.
On the PC merger: besides the aspects you pointed out, it appears to have also been nothing short of a clash of cultures.
>> Call it a Ride and you have to fight them off <<
* g * If that’s so, what about starting an effort to build a new Niagara? After all, the Brits have done it, putting some pepper to railroading that side of the Atlantic with a new Peppercorn Pacific, Tornado, incorporating some ‘Very British’ tech features, some in fact – e-hm – exceedingly British. Anyways, it seems to be a great success. There is a nicely filmed four parts video on top gear (topgear.com) a BBC TV car buff series where they revived the ancient ‘race to the north’ idea by bidding a Jag and a motor bike against Tornado with a classic ‘Flying Scotsman’. It’s in the ‘challenges’ videos file, sorry can’t get the link right now.
So, in reminiscence of NYC’s Harmon engine facilities it shouldn’t harm on Hudson to have a 4‑8‑4 storming downstream again from Schenectady to New York …
In balance, that would call for a new Pennsy Duplex, no doubt. That said, I feel there surely are people who could point to a couple more engines missing …
With regards
Juniatha
if we already know, that the steam locomotive needs (and ours) comes from water aka blue gold. more valuable than oil.
R.N.C PEACE :->
You know, there's been talk here in the USA on and off the past few years of having a Hudson or Niagara replica built, possibly in Poland, possibly in China. Nothings happened yet, so I suspect all it was was talk. But if I ever hit big on a lottery....
Several months ago I did some research on steam engine efficiency and design. Here is what I discovered. The best steam efficiency for locos was about 9%. The most efficient steam engines were made by Skinner. http://vaporlocomotive.com/ The guy who owns this company has a huge knowledge of steam engines and has all the Skinner parts and intellectual property. The Skinner engines achieved 24% thermal efficiency by using a unaflow design rather than a counterflow design, and by using a condenser. There are Skinner engines still running in stationary and marine applications. Vapor Locomotive has a large amount of engineering information on their web site about the Skinner engines. There is a company in Germany named Spilling that makes modern stationary steam engines.
The Skinner engines were a very clever design. The unaflow design gave the engines an inherent high efficiency, much better than can be achieved with a counterflow design which is what almost all steam locos used. The problems with using a unaflow design for a loco are these: The piston has to be longer than the piston for a counterflow design which makes it heavier and thus aggravates the balancing problem. The cylinder is also longer. The cylinder and piston will also be larger in diameter. The Skinner engines operates at a very short cutoff, and so the peak loads on the mechanism are higher than they are for a counterflow design.
The Skinner engines had a very clever valve gear using two cams operating poppet valves. The cams could be rotated relative to each other to change the cutoff as one cam opened the valve and the other cam closed the valve. If you read the engineering information on the design of the Skinner engine you will discover the design is very advanced and very clever.
The efficiency of the Skinner was achieved over a wide range of load conditions. A loco using a unaflow engine would have used 40% as much steam as a conventional loco. This means that the boiler, firebox, tender, etc. could all be 40% of the size of a conventional loco. A water cooled condenser near the cylinders would have avoided the problem of piping steam to a condenser behind the tender. A cooling system to cool the water from the condenser would have been needed. This could have been located behind the tender. Using a condenser would have avoided water stops and eliminated the problem of water in the western part of the country.
One of the things that always fascinated me about conventional steam locos is the lack of any seals to keep dirt out of the mechanism. The wear problem on the crosshead and reversing gear must have been serious. The diesels have a big advantage here with a sealed crankcase and oil filters.
Problems with boiler maintenance are greatly reduced when a condenser is used as there is no scale formation in the boiler. Distilled water can be used which virtually eliminates boiler problems.
Skinner had done many things when they designed their engines to eliminate maintenance problems.
The efficiency that Skinner achieved was limited by the boiler pressure available at the time they designed their engines. Raising the boiler pressure and steam temperature could improve this efficiency.
There was a comment in another post about using a water tube boiler in a steam loco. The problem with doing this is that a water tube boiler doesn't have as much reserve capacity as a fire tube boiler because there is less water. This can cause problems when the load on the engine changes dramatically. Water tube boilers are also somewhat fragile.
Bruce Baker
@ Illinois Steamhog
Ooops ?? As far as I understand, nobody here promotes large scale re-installation of classic type steam for powering revenue rail transport – at least I am not.
Talking of water – and of oil:
What has been supplied to us by nature for free in such rich quantity – so far – is in fact one central means of life on this planet. On the other hand, steam locomotives do not consume water, they just use it and then release it to the atmosphere as steam turning into fog – that’s what you actually see as what is colloquially called ‘steam cloud’ – dissolving in the air adding to its humidity and in the end falling back on ground as rain in combination with H2O from other sources. I am not claiming that all is well with that since steam exhausted by classic steam locos is not pure H2O but is contaminated by oil and dissolved or carried over matter from water treatment. Contamination by oil could be brought to zero by using modern technology, contamination by water treatment could be much reduced. The main point is: running a few steam locos for special event, i e for our ‘educated enlightening’ may be considered an ‘acceptable sin’ as regards environment pollution.
At least, it’s negligible, its contribution disappearing into microscopic scale in relation to the new horror of so called ‘bio fuel’ – fuel refined from plants and advertised as CO2 neutral, which it clearly is NOT if you just mind one thing: Where are these plants grown and harvested? On former bare desert lands? No! They are grown on areas that formerly were either farmed growing nutrition basics or – even worse as concerns CO2 balance – on areas of former natural forests or tropical jungles! In other words: areas of optimum re-conversion of CO2 into H2O and O2 are being destroyed (!!) for growing these plants of an incredibly lower performance of the same re-conversion process because of the following:
(a) While natural forests incessantly perform this process year round as they have perfectly done for millions of years without any need of ‘supervision’ and ‘correction’ by mankind, these plantations of ‘oil-yielding’ plants are periodically harvested leaving the land bare for a period of time and with zero re-conversion performance of CO2.
(b) While during its growing period a plant’s contribution to the process of re-conversion of CO2 into H2O and O2 is limited because of its own needs, yet on plantations the specially grown plants are harvested just when they have – more or less – finished their period of growth; in natural forests plants generally go through their entire life span, thus contributing way larger amounts of re-conversion even for the same type of plant.
(c) While ‘oil-yielding’ plantations are growing specially selected plants that show fast growing (mind -b- for consequence on CO2 re-conversion!), natural forests are characterized by vastly larger trees of much longer growing period followed by an even vastly longer life span as adult plants; it’s trivial to remark that quite obviously a forest with trees of some 100 ft average height functioning all year round with about 80 – 85 % of plants in fully grown status, per given area of land will have a vastly superior yearly CO2 re-conversion effect – or ‘return, if you prefer – than a plantation of plants 3 – 10 % that height, all of which are in process of growing and ‘in operation’ but some 9 – 10 months per year! yet that only counts for linear difference, a comparison of volume of chlorophyll active foliage per given area of land of natural forest versus ‘oil-yielding’ plantation would show even larger differences! without figures at hand to make a calculation my guess would be with yearly CO2 re-conversion by natural forest set as 100 % the result of ‘oil-yielding’ plantation would compare much like the thermal efficiency of classic steam and not the best examples of it.
(d) While natural forests have for eons been growing perfectly without any need of herbicides, the new human invention of so-called CO2 neutral ‘fuel by plantations’ is yet another addition to environment pollution in its demand of heavy herbicidal defence against natures efforts to ‘re-normalize’ these artificialized areas.
@ Firelock 76
Building a replica in China or in Poland:
As for Datong, I recommend Wardale’s “Red Devil and other tales of steam” to read up what state of the ‘art’ he found there.
As for Poland, my personal impression when visiting some steam facilities in the early 1990s was that while there were people of good manual and technical abilities and knowledge, especially as concerns welding of which I have seen very good practical examples, surrounding administrative and economical conditions were less than supportive. While on practical work level there were people perfectly willing to do a good job with means available, often achieving acceptable repairs in spite of tooling supply simply appalling in quality or absence there seemed to be little support by superior management level, reliability and consistency was at best uncertain. Several western investors trying to start projects had to learn this the hard way, some loosing lots of money. In defence of the Polish I have to add there was quite a flock of rather dubious profit makers roaming Poland and Eastern Europe in general in these years which surely had its negative effects on local people. However, almost two decades have passed and I don’t intend to make any claims about how things have since evolved.
Generally, having a steam locomotive the size and mass of an American Hudson or Northern built abroad would mean to see off any possibilities of line testing since mass per axle permitted on US railroads was unparalleled worldwide. Such line testing in my view would however be indispensable even with a replica as close to the original as possible. On the other hand a straight replica would appear quite improbable if you just think of one central feature of these locomotives, their one-piece cast steel locomotive bed – quite an impractical proposition for a one-of-a-kind construction today. Thus, deviations from the original design would be inevitable. Not all of these would have to unwelcome since a number of improvements could be incorporated by using post-steam technology save of any risks. Yet, I would never want to claim such an engine could be built to succeed without a period of line testing and setting up.
@ Servoguy
These are interesting points! I will look up links later when I have time. Just a few notes:
To my knowledge, best thermal indicated efficiencies in classic steam were shown by André Chapelon’s 240.P and 242.A.1 series (the latter really a single prototype rebuilt from an unhappy État railways 241.101); 12 to 12.5 % were reached at optimum working points, better than 10 % were held over a fairly wide working range with the 160.A.1 extending efficient working into the low speed range where classic steam inherently tended to fare less well. Little has transpired in literature about test results of this unique six cylinder compound with cylinder heating and re-superheating, even less has been published of data and what has been published contains a degree of inconsistence both in view of inter-relation of certain data as in view of connection of results with technical set-up of the locomotive. For instance, it was claimed that with hp superheating cut off there was no increase of steam heat consumption per ihph – which at least to me appears difficult to see. Clearly, a steam envelope on hp cylinders should have helped a lot – but nullifying the benefit of superheating? My idea of that engine – in a preliminary abstact – would propose:
(a) steam envelopes on cylinders help reduce condensation and wall effects, help keep mean temperatures up, thus gaining on thermodynamic efficiency;
(b) re-superheating again helps to raise mean temperature in lp cylinders, increasing heat content of steam in lp cylinders, containing condensation losses and wall effects and raising thermodynamic efficiency;
(c) steam envelope on lp cylinders, depending on applied steam temperatures can nullify condensation losses and even reverse wall effects which would greatly improve energy conversion efficiency of that mass of steam working inside of these cylinders; if however the balance of steam heat content saved insides the cylinders versus steam heat content spent outsides the cylinders for envelopes is a positive or a negative one, in my view remains a question demanding detailed attention in an actual application.
(d) independently from points -a- and -b- the six cylinder machine by its distribution of power, its low reciprocating masses and very good balancing, driving on three axles provided both smooth running and very low mechanical wear. This would appear self-explaining and was countered only by need for short term periodic attendance to mechanism typical for classic steam due to age-old run-through type of oiling of unsealed plain bearings. The six cylinder machine also allowed for large total cylinder volume, providing high t e while still working at much better steam expansion rates than more regular four cylinder compounds, let alone two cylinder simple machines, thus offering substantial advantages at low speed / high t e working range.
Your point
>> One of the things that always fascinated me about conventional steam locos is the lack of any seals to keep dirt out of the mechanism. <<
That is one thing I have also wondered about. The burden laden on both design and maintenance by lack of bearing sealing was appalling. Not only was wear increased, and in a progressive degree as play developed due to admitting ever more dirt to bearing surfaces, but it even affected dimensioning since bearing loads had to be kept low in view of incomplete lubrication with but semi-fluid dynamic friction. Other veritable low-tech points were design and materials of piston valve rings and piston rings and packings. I could go on with this but I don’t. Discussing similar points many years ago with my late father I had to learn that any serious deviation of the idea of American Super Power steam, namely NYC’s, having been as near perfect as practical realisations could get to in those times generally led nowhere’s – except in cases of some occasional criticism brought up all by himself *g*. If nothing else would help, he used to retreat to his standing argument “Look, it wasn’t a Rolls Royce, it was a commercial tool for railroad transport!” No-one could disagree with that and so ended the discussion. Only, if I was to reverse that argument in view of a spot that, with sharp look, might be faintly noticeable in favourable conditions of light on the varnish of his Merc, good Lord, that was something else! Oh, dad, in the end you were just a father, you did your best and I will always keep you memory dearly in my heart!
Regards
(in case of trouble with text font / size please feel free to ask me for a copy in Arial)
The 9% t e was for a simple expansion loco. Clearly you can do better with compound expansion, and Mr. Chapelon was an expert at getting the most power for the amount of steam used. Still, a unaflow engine will do better than a compound expansion with less complexity. After you have read the stuff on the Skinner engines, I think you will be most impressed with the design.
The out of balance force on a single cylinder engine, assuming the engine is balanced so that the counterweight equals all of the rotating weight plus half of the reciprocating weight, is a force equal to half of the reciprocating weight that rotates in the opposite direction to the driver. This out of balance force can be balanced by making the engine a 90 deg V-2 or by adding a counterweight that rotates in the opposite direction of the driver and is equal to half the reciprocating weight. Based on the fact that a unaflow engine would have a boiler 40% of the size of the boiler for a conventional loco, there might have been room to add two vertical cylinders to the loco and thus achieve near perfect balance. The balance isn't perfect due to the connecting rod angularity, but in a steam loco, the angularity is pretty small.
Skinner built both simple and compound engines. One of the finest engines they ever built is still in a ship on the great lakes. There are some good pictures of it along with pictures of the internal parts. I think it was installed in 1950. It has one huge advantage over a diesel: it can be reversed very quickly.
When you read the Skinner information, you will see that they did a continuous development to reduce or eliminate maintenance. That may be why many of their engines are still running.
Link to the info about the Skinner in the great lakes ship: http://www.carferries.com/skinner/
I found this recently and thought it might be of interest:
http://www.internationalsteam.co.uk/trains/newsteam/modern50.htm
It is a very good article on what modern steam could be.
The entire article has a strong taste of "What might have been?" Something that hasn't been considered: What would happen to the price of coal if railroad demand for PRB coal as fuel was added to the existing utility demand for the same coal? Also, railroads would have to rebuild an entire infrastructure to support steam.
CSSHEGEWISCH The entire article has a strong taste of "What might have been?" Something that hasn't been considered: What would happen to the price of coal if railroad demand for PRB coal as fuel was added to the existing utility demand for the same coal? Also, railroads would have to rebuild an entire infrastructure to support steam.
PRB coal in a steam locomotive? It would be next to useless in a locomotive application. You would probably get more power burning dirt.
servoguy I found this recently and thought it might be of interest: http://www.internationalsteam.co.uk/trains/newsteam/modern50.htm It is a very good article on what modern steam could be. Bruce Baker
How do you run a simulation with RTC, using a mythical 2-8-8-2, with non-existent data? Well, you can...if you just make the data up. LOL
The entire basis of any computer model is you have to have actual, confirmed data to model. Other than that, running a simulation is just an example of garbage in = garbage out.
EDIT: I decided to tone the original post down on my own. I will address my issues with the link at a later date, when I have time.
servoguy I found this recently and thought it might be of interest:
What I find very uninteresting is the background pattern used in the piece. It is very distracting, making the article difficult to read. Juniatha, are you paying attention here?
.
GP40-2 servoguy: I found this recently and thought it might be of interest: http://www.internationalsteam.co.uk/trains/newsteam/modern50.htm It is a very good article on what modern steam could be. Bruce Baker John Rhodes is just plain nuts. How do you run a simulation with RTC, using a mythical 2-8-8-2, with non-existent data? Well, you can...if you just make the data up. LOL The entire basis of any computer model is you have to have actual, confirmed data to model. Other than that, running a simulation is just an example of garbage in = garbage out. Just so everyone know who wrote this analysis, John Rhodes has an undergrad degree in Cooking (I'm not kidding) After not making it as a chief, he attended grad school to get a degree as a "Transportation Analyst" (Whatever that means). His whole RR knowledge base was obtained from riding Amtrak with his parents. (Really, I am not making any of this up!) No background in Mechanical Engineering, no advanced math or science classes, no Class 1 work history. Nothing. Zilch. Nada. Then you all wonder why nobody who actually works in railroading takes any of this seriously.
servoguy: I found this recently and thought it might be of interest: http://www.internationalsteam.co.uk/trains/newsteam/modern50.htm It is a very good article on what modern steam could be. Bruce Baker
John Rhodes is just plain nuts. How do you run a simulation with RTC, using a mythical 2-8-8-2, with non-existent data? Well, you can...if you just make the data up. LOL
Just so everyone know who wrote this analysis, John Rhodes has an undergrad degree in Cooking (I'm not kidding) After not making it as a chief, he attended grad school to get a degree as a "Transportation Analyst" (Whatever that means). His whole RR knowledge base was obtained from riding Amtrak with his parents. (Really, I am not making any of this up!)
No background in Mechanical Engineering, no advanced math or science classes, no Class 1 work history. Nothing. Zilch. Nada.
Then you all wonder why nobody who actually works in railroading takes any of this seriously.
RTC isn't really the right tool for the job, either. It does OK, but really doesn't have (or need to have) a first class train performance calculator built into it. It's main purpose is line capacity modeling. It needs a TPC to get close to actual running times - but that's it.
But, that said, the results are obvious. More HP = shorter running times. It also means more energy spent which means more fuel consumed, regardless of which fuel or thermal efficiency of the engine.
I'm also not liking the drawbar HP diagram used for the diesel locomotive. The net traction HP doesn't drop off that drastically with increasing speed and for typical trains, the % of HP spent moving the locomotive compared to the rest of the train is rather small.
-Don (Random stuff, mostly about trains - what else? http://blerfblog.blogspot.com/)
GP40-2 servoguy: I found this recently and thought it might be of interest: http://www.internationalsteam.co.uk/trains/newsteam/modern50.htm It is a very good article on what modern steam could be. Bruce Baker How do you run a simulation with RTC, using a mythical 2-8-8-2, with non-existent data? Well, you can...if you just make the data up. LOL The entire basis of any computer model is you have to have actual, confirmed data to model. Other than that, running a simulation is just an example of garbage in = garbage out. Just so everyone know who wrote this analysis, John Rhodes has an undergrad degree in Cooking. He attended grad school to get a degree as a "Transportation Analyst" . No background in Mechanical Engineering, no advanced math or science classes, no Class 1 work history. Then you all wonder why nobody who actually works in railroading takes any of this seriously.
Just so everyone know who wrote this analysis, John Rhodes has an undergrad degree in Cooking. He attended grad school to get a degree as a "Transportation Analyst" .
No background in Mechanical Engineering, no advanced math or science classes, no Class 1 work history.
My email is around the internet in several places. If you have a problem with my work then you should have contacted me. The data on the 2-8-8-2 isn't non-existent. It came from Shaun McMahon and was checked over by Nigel Day as well. I am assuming you know who they are, if you don't then you should learn before making comments like this. If you think their data is wrong then you should take it up with them.
I may have an undergrad degree in Culinary Arts Management from the Culinary Institute of America but I do have a Masters Degree in Transportation Policy Operation and Logistics from George Mason University. I have spent the last 6 years working professionally in the railroad industry.
I may not have a degree in Mechanical Engineering but I know alot about steam locomotive engineering.
John Rhodes
oltmannd:
I used RTC because that is what I had access to. You are correct that other models are more focused on the TPC role as a primary. But over my several years of using RTC I would not say it produces poor TPC results when setup properly.
Can you provide this alternate Diesel DBHP graph with reference. I would be interested to see it.
Don't knock people who don't have formal training. Thomas Edison was kicked out of school for being stupid and he became a newspaper delivery boy and telegraph operator before coming up with 1200 patented inventions.
But getting to the jist of this post, it might be worthwhile to consider external combustion instead of just "steam". In external combustion the combustion process is "continuous" and can thus be more carefully controlled. Also, doesn't water have a rather high specific heat? So maybe we should also consider a medium other than water in a closed circuit that includes a condenser.
Folks, let's ratchet down the personal attacks. These forums are here to have friendly conversation in a fun, non-confrontational environment.
Okey-doke?
John
I don't have any hard data, but I did participate on drawbar HP tests of C36-7s and SD50s on Conrail's Boston Line (many moons ago!) and my recollection is that the net traction HP variation with speed is almost nill. You do have to account for the rolling resistance of locomotive to get from net traction HP to drawbar HP (plus train acceleration), but that's only going to be a few percent of the total train resistance and is generally a wash from locomotive to locomotive.
jwhitten Folks, let's ratchet down the personal attacks. These forums are here to have friendly conversation in a fun, non-confrontational environment. Okey-doke? John
Wow. My very own thread!
My comments were strictly objective about the nature of the TPC and RTC modeling tools - an area where I do have some expertise. If anyone took offense, I apologize. It was never my intenet.
oltmannd Wow. My very own thread! My comments were strictly objective about the nature of the TPC and RTC modeling tools - an area where I do have some expertise. If anyone took offense, I apologize. It was never my intent.
My comments were strictly objective about the nature of the TPC and RTC modeling tools - an area where I do have some expertise. If anyone took offense, I apologize. It was never my intent.
oltmannd: I wasn't offended. I was just trying to explain my use of RTC in response to your reasonable question.
Just because someone doesn't have formal training in a subject does not mean they cannot contribute anything. Read up on Michael Faraday.
Getting back to steam locomotive efficiency. From my observations this whole discussion can be distilled down to a few main points.
1. Will a steam locomotive ever approach the thermal efficiency of a diesel without a turbine-electric drive, condensing into a vaccum, water tube boiler, closed loop, overly complicated and delicate system? No.
2. Ideally, the rail line should be electrified (indirectly powered by steam). However, this is impractical and the infrastructure too costly for the transcontinental routes.
3. Efficiencies of 12-15% for a modern steam loco (probably requiring compounding) using all of Chapelon's, Porta's, Wardale's, et al improvements. Of course this is still 2-3 times lower thermal efficiency of a diesel. However, the economic advantages of using domestic sources of or what would be otherwise waste for fuel can overcome the thermal efficiency disadvantage.
4. As Porta points out, the construction & maintenance of steam locomotives require much less capital investment and precision, a huge plus for places with lower skilled labor forces and the less developed countries.
5. The high specific heat of water is both a benefit and a disadvantage. The high heat capacity of water allows large amounts of energy per unit mass flowing through the engine. Water is cheap and plentiful, requiring treatment where needed. Not to mention many of the other fluids for a substitue in the Rankine cycle are poisonous and/or corrosive to common metals.
Cheers - Joe
"If a nation expects to be ignorant and free, it expects what never was and never will be." Thomas Jefferson
oltmannd I don't have any hard data, but I did participate on drawbar HP tests of C36-7s and SD50s on Conrail's Boston Line (many moons ago!) and my recollection is that the net traction HP variation with speed is almost nill. You do have to account for the rolling resistance of locomotive to get from net traction HP to drawbar HP (plus train acceleration), but that's only going to be a few percent of the total train resistance and is generally a wash from locomotive to locomotive.
One of the first things I noticed from the link, like you, was the drawbar HP for the ES44AC used as an example was off at higher speeds. Way off. There is no way an ES44AC loses 1000 HP at 70 mph. That's why I said it was nuts.
You are absolutely correct that net traction HP in a diesel-electric does not vary with speed, with the exception on an AC unit at extremely slow speeds where the unit will derate to maintain maximum adhesion.
For others reading this, the reason is simple. A Diesel-Electric Locomotive is an electric locomotive that carries its own power plant with it. The diesel engine, traction alternator, and electrical system could care less if the locomotive is going 10 mph down the tracks or 100 mph. It is generating electricity, the traction motors are converting the electricity into rotational force, and the whole thing is just going along for the ride.
The net traction HP is the same at 70 mph as it is at 10 mph. The only thing changing is the rolling resistance and air resistance at 70 mph, which for the ES44AC amounts to around 200 HP. So the drawbar HP of an ES44AC at 70 mph is only 200 HP less than it was at 10 mph, NOT 1000 hp.
Every ES44AC I am familiar with is producing close to 4000 DBHP @ 70 mph. CSX's GEVO-16 engined AC6000s are producing 5600+ DBHP @ 70 mph.
GP40-2 oltmannd: I don't have any hard data, but I did participate on drawbar HP tests of C36-7s and SD50s on Conrail's Boston Line (many moons ago!)... ... Every ES44AC I am familiar with is producing close to 4000 DBHP @ 70 mph. CSX's GEVO-16 engined AC6000s are producing 5600+ DBHP @ 70 mph.
oltmannd: I don't have any hard data, but I did participate on drawbar HP tests of C36-7s and SD50s on Conrail's Boston Line (many moons ago!)...
I don't have any hard data, but I did participate on drawbar HP tests of C36-7s and SD50s on Conrail's Boston Line (many moons ago!)...
...
GP40-2:
I am interested in seeing your data. And also you haven't said what your credentials are to prove I am wrong, unintelligent or don't know what I am doing. Why don't we treat people with some civility around here.
My ES44AC DBHP data is derived/estimated from data in an EMD Product Application Guide since I can find no source for actual DBPull or DBHP data on the GE ES44AC. If you have it prove me wrong, I would be interested in seeing it. Until then I am sticking with a drawbar horsepower (not net traction HP) estimate based on real manufacturer's data and not opinions.
I have two questions. . .
Was EMD also the source of the ES44AC tractive-effort data, particularly for speeds below 10 mph?
What are the 2-8-8-2 driving-wheel axle loadings?
Thank you.
JayPotter I have two questions. . . Was EMD also the source of the ES44AC tractive-effort data, particularly for speeds below 10 mph? What are the 2-8-8-2 driving-wheel axle loadings? Thank you.
At one point the Starting and Continous Tractive Effort ratings where listed for both the GE ES44AC and DC on GE's website. This is what I used, however the information appears to not be listed anymore.
On the 2-8-8-2, my modern steam locomotive source said they locomotive would need to be ballasted to reach a 71,500 pound axle loading (standard 286k).
Thanks for the questions, John Rhodes
GE's high-TE ES44AC -- which some railroads have acquired instead of the conventional version -- has an axle loading of 72,000 pounds and a starting TE of 200,000 pounds. Probably more significantly, its traction control software can shift TE from low-adhesion axles to high-adhesion axles, up to a per-motor limit of 36,000 pounds. So even if rail conditions won't allow it to reach the 200,000-pound TE limit, it will get closer to that limit than it would if it had the conventional per-motor limit of 30,000 pounds. Knowing next to nothing about steam locomotives, I have no idea of the probability of the 2-8-8-2 reaching its180,000-pound maximum TE (which I gather would equate to about 31.5% adhesion); however it is not unusual for the high-TE ES44ACs to reach their 200,000-pound limit (which equates to about 46% adhesion) when that level of TE is needed.
I am coming late to this discussion as I rarely read the Steam and Preservation board. In reading the SD70MAC shop manual it talks about operation of the locomotive at speeds where main generator (alternator) output is at maximum voltage. It states that if the motor's rotational speed increases the rotor's inductive reactance will increase reducing the current flow in the rotor and the torque of the motor. This means that at higher speeds the drawbar horsepower must fall once the inverters reach their limits and the main alternator reaches maximum voltage. There is no reason to believe that GE's don't have the same limitations even if the exact speed at which this happens is not the same. What the manual says is that once maximum high power switching speed is reached, and the Main Alternator is supplying its maximum voltage, operation of the motors at higher speeds will result in a reduction of motor torque.
The net traction HP is the same at 70 mph as it is at 10 mph. The only thing changing is the rolling resistance and air resistance at 70 mph,
HP for traction may not change but Tractive Effort certainly does.
LDPorta My ES44AC DBHP data is derived/estimated from data in an EMD Product Application Guide since I can find no source for actual DBPull or DBHP data on the GE ES44AC.... John Rhodes
My ES44AC DBHP data is derived/estimated from data in an EMD Product Application Guide since I can find no source for actual DBPull or DBHP data on the GE ES44AC....
I'm curious, since you don't have access to actual GE test data, what lead you to believe that you could use EMD data on a GE product that uses a completely different inverter system? What exactly did you use from EMD, and what was your methodology to transform EMD data into your opinion of GE product proformance?
Also, since you don't have actual test data from GE (I know they won't give it to you since it is GE's corporate policy not to discuss engineering data with non-customers), why use an ES44AC in your example? Why not use the EMD product you claim to have got the data from? Seems pretty shady for you to represent a GE product in your presentation, when you publicly admit you have no actual data on said product.
My background ?
Dual Major in Mechanical Engineering and Physics undergrad+ Masters in Mechanical Engineering, both from two Top 10 Engineering Universities. Plus, going on 33 years experience in the industry.
beaulieu There is no reason to believe that GE's don't have the same limitations even if the exact speed at which this happens is not the same...
There is no reason to believe that GE's don't have the same limitations even if the exact speed at which this happens is not the same...
GE's use a completely different, more advanced, and much higher performance inverter system than EMD. Comparing the two is like comparing a 1932 Chevy to a 2011 BMW.
Haven't any of you guys wondered why the MBTA, an all EMD DC operation up to this point in time, specifically is getting GE based AC technology for their new high speed, high power commuter locomotives, which are a prelude to the next generation AC AMTRAK locomotives? I give you a big hint: it isn't the GE's are cheaper either (over $5 million per locomotive), it has to do with the performance of GE's electrical system at high speed.
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