4-6-4 vs. 2-8-4 question.

Ed King's analysis of the N&W vs C&O bottomline performance was most interesting. I would submit some of the C&O's mediocre financial performance may lay with managerial ineptitude. The C&O invested a huge amount of money in steam locomotive aquisitions in the late 1940's (quite late in the steam season), then wrote the whole lot of them off in the early 1950's. Then more folly: it appears the C&O overbought diesels and ended up with a surplus of motive power in the recession of 1957-58, which got leased out to other roads and which knocked out some of the final pockets of steam power on the Baltimore & Ohio and Nickel Plate in Spring/Summer 1958.

      Here's a magnificent display of what 5000+ horsepower at the drawbar looks like, wherein #611 slips to a full stall on Saluda (the steepest mainline grade in the USA - 4%), builds up a full head of steam, then proceeds to march triumphantely up that severe grade from a dead standstill!   http://www.youtube.com/watch?v=NUPIynJq7tg

I'm willing to bet that the blame for C&O's poor performance can land right the feet of Robert Young, who also helped ruin the New York Central.

Stuart

Dave, There's another one in Proctor, MN sitting by the new museum. Two Harbors at one time had a pair of Yellowstones but in the late 60's or early 70's one got scrapped

mark s -

The 611 stalled on Saluda because the sand quit running.  If you'll study the video, you'll see a guy go up on the running board and get into the sand dome; he reaches in and moves sand down where it will run into the sanding system.

After the sand was running, Bob Saxtan started the train again.  It certainly didn't run out of steam.

EdKing

There was plenty of steam, but no sand equals....well what you saw.  The power of the "J" was shown when the sanding issue was fixed and she pulled the train up there from a dead stop.   

Vid of 611 in 1983, Atlanta to Chattanooga, runby starting at 1:38 to 3:38. 

http://www.youtube.com/watch?v=H7yXv4UUxqw

This is the first time I've ever been able to HEAR the J's horsepower curve.  Check it out: 1:38 - easy start; 1:59 - start of serious work; 2:14 - check the sound here as she really gets rolling; and 3:12 - stand back, this is what a J can do with the equivalent of a 17-car train.  No eight to 12-car fluff stuff.  If there’s a better example than this, please post the link!

A common mistake...Tractive Effort is only distantly related to how "POWERFUL" a locomotive may be. HORSEPOWER AT SPEED is what is important.

An example...the Erie Triplex had 176,256 lbs. of Tractive Effort, but could not develop enough HORSEPOWER to pull anything at a significant speed. N&W's own Y6b articulateds could develop 152,206 lbs. of tractive effort, but they did not have the power to run at speed with the same load that the J could. The J has more HORSEPOWER than the Y6b. Even some 0-10-0 switchers could develop more Tractive Effort than the J, but they had nowhere near the HORSEPOWER of the J.

Tractive Effort is only half the story when it comes to determining the POWER of a steam locomotive.

The "A" produced 6300 drawbar horsepower.  It had a 122 sq foot grate vs the Y6b which had 106.2 sq. feet. They both had 300 lbs boiler pressure; the A could just plain produce more steam for over the road power. The A also had a much larger evaporative surface of 9342 sq feet vs. the Y6b at 6393 sq feet.

       It was observed by Robert LaMessena, the excellent steam locomotive analyst (he is a mechanical engineer), that the roads that ran their freight trains somewhat shorter but significantly faster were the same roads that had the best bottom line results. Union pacific, Santa Fe and Nickel Plate are prime examples. Essentially they ran their steam locomotives in the most productive part of their power curves. Additionally, they were over the road and pulling a second revenue generating train, while the roads operating with a "drag era" mentality, were still limping toward their terminals. The N&W ran their trains in tandem with the maximum power output of it's locomotives. A Y6 developed it's maximum at a much lower speed then an A, whatwith 58" drivers......but that's optimum for coal train and pusher service. Their engines were matched with the appropriate service.

Ed, you can pick "bones" with me any time, pardner.

Even though I may have gotten the numbers wrong on the Y's, the point I was trying to make was that Tractive Effort alone does not tell you how POWERFUL a steam locomotive is. Whenever you talk about the generation of POWER, speed comes into the equation. POWER is a measure of HOW FAST a given amount of work can be done.

That Erie Triplex could probably move 10,000 tons of coal from Williamson to Roanoke unassisted, but it would probably take several days to do it! A Y could do it in a few hours.

The Triplex has more Tractive Effort; the Y has more power. THAT is my point.

Rich's perspective is much appreciated as a man who has actually run steam locomotives. One must keep in mind that EMD had to couple up 4 diesel locomotives to beat 1 steam locomotive! Those good old iron horses sounded powerful, and by God, they were!

Great discussion. Christopher Chant in his book THE HISTORY OF NORTH AMERICAN STEAM, makes the statement which I find questionable, that the DM&IR M3 and M4 Yellowstones could pull three times the load of the Big Boy, when the Yellowstone only had only 4665 lbs of TE more than the BIG BOY. If this is a true statement, what in the world was the horsepower of the M3 and M4. I`ve read the Big Boy had 6000hp. Any one with answers or is Mr. Chants` statement overstated. I have read that the Yellowstone could pull unassisted 180 loaded iron ore cars over relatively flat terrain.

Bob

That wildly overstates the DM&IR Yellowstone horsepower. Here is the CALCULATED boiler horsepowers for a number of big articulateds: Great Northern R2 2-8-8-2 (6820); WP 2-8-8-2 (6590), DM&IR 2-8-8-4 (7140), UP 4-8-8-4 (6520) and C&O 2-6-6-6 (7330). Do recall, these are "calculated", not dynanometer measured figures. I would wager the Big Boy has more horsepower then calculated here. It had a huge 150 sq. foot grate area and 300 psi boiler pressure. The Missabe engine had 125 sq feet and 240 psi, so suspect the Missabe figure. Maybe there was some "magic" done with the cumbustion chamber, but the Big Boy certainly would have had a comparable cumbustion chamber.   My horsepower data comes from p.237, "Steam Locomotives of the Great Northern Railway" (BTW, an absolutely outstanding book, which I heartily recommend).

The Missabe Yellowstones did pull the heaviest freight trains drawn by steam locomotives in the world, approximately 18,000 tons, but it should be recalled that they were pulling loads eastbound into the Lake Superior bowl, so weren't really fighting gravity. Additionally, they got a boost from a yard SD9 or steam locomotive to get their trains rolling. Great Northern N3 2-8-8-0's pulled about the same tonnage trains, too.

Maybe they could pull that kind of load, but at what SPEED? Without a speed reference, there is no "power" to compare. Tractive Effort alone is NOT "POWER." It is only one part of the power equation. Ya gotta know the speed, too.

A little 600 hp SW1 could pull an 18,000 ton train if it was downhill! 

The Missabe Yellowstones headed toward Proctor Yard pulled 18,000 ton iron ore trains at 35-40 mph, once started. The route was pretty flat and presume that 35-40 mph was pretty close to the Yellowstone's "sweet spot". Now Yellowstones, when working into Two Harbors, were limited to about 6500 tons, as it was a much hillier profile. But, under any circumstance, Missabe Yellowstones were VERY formidable locomotives. I recall a Wm. Middleton article in Trains Magazine, wherein Mr. Middleton rode a Yellowstone in the big shipping rush of 1959 (due to an impending Steelworkers strike) which resulted in the firing up of about 40 or 50 Missabe steam locomotives, and where his 18,000 ton Yellowstone-powered train sailed by a stalled trio of re-geared leased Great Northern F7's. Heh heh!!

The Big Boy was handicapped by the poor quality 8000+ BTU coal that UP used. N&W used coal having over 14,000 BTUs. NYC "passenger coal" was 13,800 BTU/lb.

The "running drawbar pull", as Rich stated, is what determines the drawbar HP of a steam locomotive. As a matter of fact, there is no way to measure horsepower directly....the pounds of pull are measured along with the speed at which the DB pull was measured. Multiply the speed in mph with the DB pull at the tender coupler in pounds, divide by "375" and you have the drawbar HP AT THAT SPEED.

The N&W A class was measured by PRR in over the road testing to have 5200 drawbar HP, not 6300. (An old N&W Mechanical Dept. employee by the name of Bob Hord, now deceased, told me that Pond was "embarrassed" that the 6300 number ever got out....). He also told me that on the steam and diesel tests on N&W using four EMD F units, that the N&W "hot oiled" all of the journals in the train for the steam runs. EMD also set their injectors higher, and evidently neither side was aware of the "efforts" of each camp to make their champion win.....

He also told me that a J on occasion reached 105 mph eastbound whenever the train was late out of Crewe, as they could leave Crewe 20 minutes late and arrive at Norfolk on time.

The N&W J class was measured, per Pond, in a Railway Mechanical Engineer article dated June 1946 as having a maximum of 5028 DBHP at 41 mph.

In service, a N&W J could handle a 15 car passenger train from Roanoke to Bluefield. In practice, per Ken Miller's book on the J, the average trailing cars on the Cavalier was 12 westbound (Norfolk-Cincinnati) and 13 eastbound (page 77), not 16.

The J's were (are) great locomotives, and they, as all N&W power, were optimized for N&W and for specific service. In particular, the use of 70" drivers may have been to minimize driving wheelbase length for better performance in curvature. 

As a railroad fleet, N&W steam was probably the most efficient. To compare on a roster size basis with NYC, for example, which had "hundreds" of WWI Mikes and over 1000 0-8-0's, this would be misleading. As an example, a NYC Niagara boiler could evaporate more water per hour than a N&W J, while burning less coal. (The Niagara over-the-road peak evaporation, confirmed in tests, was over 117,000 Lb. per hour, exceeding an N&W Class A Mallet.) So N&W "did not boil water" better than everyone else.....

My comments re the N&W J as a "freight design" was the result of a comparison of other Northerns that ran in N&W territory. here are two:

C&O J-3 

Calculated starting tractive effort: 68,300

Booster 12,400

Drivers 72" (The C&O diagram book says 73")

Cylinder Dia.and stroke: 27-1/2 x 30"

Adhesive weight: 282,400 lb.

Western Maryland 1400 series 

Calculated starting tractive effort: 70,600.

Drivers 69" 

Cylinder Dia. and Stroke: 26-1/2 x 32"

Adhesive weight: 290,000 lb.

The C&O was principally a passenger engine until near the end of its service life, when it hauled freight. The WM was a freight design.

And here is a NKP Berk:

Calculated starting tractive effort: 64,100

Drivers 69"

Cylinder Dia. and stroke 25 x 34"

Adhesive weight: 264,300 lb.

Obviously a freighter (see driver size), but a high speed freighter (see cylinder diameter)

Cylinder diameter and stroke, and driving wheel diameter determine the speed range at which maximum drawbar HP occured, and this was adjusted for each railroads' ruling grade, tonnage to be hauled, etc. As a good example, the C&O 2-8-4 has the same grate area, heating surface, etc etc as a NKP 2-8-4. However, the C&O 2-8-4 has 26" cylinders, a booster, and much more adhesive weight (293,100 lb.) for service in heavily graded territory.

High speed Northerns, that is, those designed to run at high speeds on a daily basis, had 79-80" drivers and cylinders around 25" in diamater, to provide peak HP at much higher speeds than the N&W J.

You would need a book to compare C&O operations vs. those of N&W. Over 76% of N&W revenues right after WW II were from coal, and N&W never did have the number of branches that C&O did. (Look at each RRs map.) So operationally, N&W could be more efficient in all areas from the types of freight cars to the types of locomotives. N&W did not correct their reliance on one principal commodity until they merged with the Southern, and acquired NKP and Wabash in the 1960's.

Please excuse me for my ignorance.  I have read many of these this vs. that topics with great interest. Steam vs. steam, diesel vs. steam and so on. 

For instance the class A above at 5,200 HP. Is not what is being said that the locomotive can hold a constant velocity of one meter per second against an opposing force of 3,879,200 Newtons. 

Or and ES44AC at 4,400 HP can hold a constant velocity of one meter per second against an opposing force of 3,282,400 Newtons. 

If one goes faster than one meter per second that would mean the opposing force would be less. However, being able to do one meter per second against an opposing force of 3,282,400 Newtons does not necessarily mean that one will be able to do two meters per second against an opposing force of 1,641,200 Newtons, but doing two meters per second against an opposing force of 1,641,200 Newtons is the same work being done as one meter per second against an opposing force of 3,282,400 Newtons.

for me, this has been one of the more interesting threads in quite a while.

Like to thank everyone for their input.

 I also recommend  the two Articles in the ARROW previously noted.

What's a "meter" and a "Newton"?

A meter is a unit of distance defined to be one ten millionth of the distance from the equator of Earth to the North Pole of Earth. Now it is defined to be a particular distance light travels per unit of time in a vacuum. The meter is the International System Unit for distance.

A Newton is named after Sir Issac Newton and is the International System Unit for force.  It is equal to the amount of net force required to accelerate a mass of one kilogram at the rate of one meter per second squared.

How about translating that into English, please? I have absolutely no idea what you just said.

What's a "meter" and a "Newton"?

No wonder EMD left Canada. 

WBC

To avoid the whole English-Metric thing we are using pounds of force instead of newtons and Miles Per Hour instead of Meters Per Second.  But the concepts remain the same.

A significant difference between diesel-electrics or electrics and steam locomotives comes from the fact that diesel-electrics and electrics have the prime mover disconnected from the traction motor.  A diesel engine/generator set or remote power plant can operate at its peak of power output even when the locomotive is starting.  The only limit is the amperage limit of DC traction motors at low speed.  Locomotives with AC traction motors do not have the dame limitation and can produce tractive efforts at very low speeds as great or greater than the largest articulated steam locomotives.  This gives diesel-electrics or electrics a tremendous advantage on mountain railroads since they can utilize their maxim horse power to move heavy tonnage at low speed.  Except for very early electrics they also avoid the problem of balancing reciprocating machinery at higher speeds.  They do suffer a fall off of torque or tractive effort rather quickly as speed increases but are very versatile machines over a wide range of operating conditions.

A conventional steam locomotive is a reciprocating engine connected directly to the drive wheels.  It produced peak torque, and therefore tractive effort, at starting speed but very little horse power since velocity is low and there are few power impulses at low RPM.  As speed increases horse power increases rapidly.  Torque falls but it tends to do so more slowly than is experienced by locomotives with electric traction motors.  Steam locomotives tend not to be very versatile since the size of the drive wheels, cylinder size, boiler pressure, evaporating capacity, degree of superheat, etc are the results of tradeoffs to produce a locomotive optimized around producing the right amount of tractive effort at the right speed to produce the required horse power for a particular type of service.  And steam locomotives designs then to also be based on a particular type of fuel which, as has been pointed out in this conversation, can vary widely in energy content and other qualities.

The N&W J is a noteworthy machine because it can produce as much starting tractive effort as any engine with eight drive wheels (although it is more prone to slip than some since it is not the heaviest on its drive wheels) and yet can produce peak horse power over a wide range and continue accelerating a significant size train up to and beyond 100 MPH.  And, not only does it perform spectacularly it had lower maintenance costs than many comparable steam locomotives.

The N&W A and Y class locomotives were remarkable as well as fast freight and heavy haul locomotives.  Again, they are more versatile than many comparable locomotives and very efficient when operated in their intended service.  They could make a good economic argument for sticking with steam in the first decade of the road diesel.  By the time the F9 and GP9 arrived diesel prime movers and traction motors had advanced to the point where diesels could go head to head against the best steam under the conditions it was designed for, beat it and then face another type of steam locomotive designed for a different kind of specific service and beat it too.  Four GP9s could out lug a Y-6, out hustle an A on fast freight and, with re-gearing and a train heating boiler or boiler car outdo the best steam passenger locomotives.

Too many numbers flying around here to answer tonight.  However, one has got to be put in perspective.

The Niagara did NOT evaporate 117,000 lbs of water over the road.  This is equivalent evaporation.  The total evaporation during the same test (including FWH was 88,830 lbs per hour.  All these figures are from the Niagara test data.

The N&W A  produced 116,000 lbs of steam total evaporation (test data).  This is not equivalent evaporation.  Using roughly the same measurement, equivalent evaporation for the A would have been in the range of 145,000-150,000 lbs per hour at 275 psi and 280 deg superheat.  This is myy estimate, not from N&W test data.  At the time of the test, the A's pressure was not yet raised to 300 psi.

Be back tomorrow.

Actually EMD (CAT) left Canada because of the CAW!

What's a "meter" and a "Newton"?

 

No wonder EMD left Canada.   

Actually EMD (CAT) left Canada because of the CAW!

Apparently the CAW couldn't do the math either. 

I’m sorry; in my profession I use the metric system. Sometimes I forget that it is still not common in the USA to use SI units, but everywhere else in the world does.

Well, here it goes. This is what I was trying to get at. Concepts such as “power”, “work”, “speed” and such are being thrown about without, as it seems to me, without much care.

Horsepower has a definition to it.   One horsepower is defined as the ability to hold at constant velocity of one meter per second against an opposing force of 746 Newtons, or 746 N m/s, which is also a way of saying 746 Watts. The units of the Watt are Newtons, meters, and seconds.  The Watt is the International System Unit of power. A watt is the rate at which work is done. This is true for both diesel and steam locomotives and any other machine or being. Steam locomotives elsewhere in the world are rated in Watts as are diesels and electrics. The Watts can be divided by 746 to give horsepower.

For instance, I remember a post that went something like this: 765 is pulling a 30 car passenger train in tandem with a diesel locomotive of similar horsepower. The throttle of the 765 is throttled into such a position so its net force on the train is zero and only the diesel was doing the work. The result was the diesel could only go 30 mph with the 30 car passenger train. However, 765 by itself could pull the train 60 mph (maybe in the 50’s but I am making the math easier).  Here are two supposedly equal power machines with one (the steam locomotive) seemingly doing a vastly superior job. In this case it would be true, by the definition of the Watt; the steam locomotive is doing twice the amount of work.  While not explicitly stated, it was certainly suggested as to which machine was superior.

But that is not the end of the story. Now give an opposing force more suitable for the diesel; double the number of passenger cars to 60. No doubt that the diesel of equivalent horsepower can get such a train started. It still should move, in theory, at constant velocity of 30 mph. In other words, 30 cars at 60 mph is the work equivalent as 60 cars at 30 mph if the opposing force given by the cars is proportional.Can the 765 pull 60 passenger cars?  At what velocity? At some point it will equal out.

Now the similar horsepower diesel is doing an equivalent amount of work against an opposing force as the horsepower of the 765. One machine is pulling a lighter load more quickly and another machine is pulling a heavier load more slowly, but both doing an equivalent amount of horsepower and an equivalent amount of work in terms of the Watt.  

This is why I find these this vs. that threads so fascinating. Ultimately machines are designed to do particular jobs. Just because two machines are of equivalent horsepower does not mean that they will do a particular task equivalently. There is a choice as to what to do with the power to move: one can apply that horsepower to move at velocity a lighter object more quickly or one can apply the horsepower move at velocity a heavier object more slowly. And while yes, it does take more power to move at a faster velocity, it also takes more power to move a heavier object at a given velocity. But to say horsepower is equal to speed is incorrect, it is better to say that more horsepower = more work being done be that work going faster with a lighter load or slower with a heavier load. So in these this vs. that threads everything equals out when the machines do the job that they are designed to do.

Obviously there is another point.  That point is the amount of consumption to produce the Watt. However, that is a completely different topic.

Yeah,. none of which answered my theroetical question of how many passenger cars a little NKP Hudson could possibly pull up the Gorge....

Well...this is where I get off this train. It has gotten WAY too technical to suit me.

The N&W had a Test Engineer named Robert M. Pilcher (a Mechanical Engineer, BTW) who probably spent as much time with their dynamometer car as he did at home with his family.  He was not happy with the 6,300 reading on the first test of the A.  He felt it was too high.  Some time after that test, he disassembled the Dynamometer Car's recording drawbar and all its related mechanism and rebuilt it; it hadn't had such attention since the car was new sometime before 1920.  He was more satisfied with later readings that showed the A about 5,350 DBHP.  (Bob very kindly provided me with considerable data which I used in writing the book on the A; he also was extremely helpful to L. I. Jeffries with his "N&W-Giant of Steam" book.)

5432, it's interesting that you invoke the name of Bob Hord, whom I knew years ago and who was not a Mechanical Engineer (I hate to discuss the deceased in this way, but I'm going to) and who evidently figured that he'd been passed up for several promotions, and by the time I knew him he was a well known malcontent around the railroad.  (When I knew him, he'd been shunted out to Decatur to do some quasi-clerical job). He told me some stories about N&W power that I later found out were not true, and he evidently passed some on to you.  Bob and his father had several shares of N&W stock, and it's on record that they enjoyed showing up at stockholder's meetings and sought to embarrass management (in that time frame, N&W common was paying around $6.50 per share, the highest on the NYSE; I wonder what part of that was unsatisfactory to the Hords; Bob was unable to understand that those little episodes might have had something to do with his not being promoted).   I've also heard the hot oil, etc. argument and it can be discounted along with everything else you heard in that vein.  The F7 horsepower increase cannot be discounted, since it was obvious that the F7 was performing better with N&W's Dynamometer Car than EMD's own power output charts indicated that it should; Bob Pilcher confronted the EMD people along for the test who admitted that they'd "adjusted" the fuel racks and load regulators and the F7 was actually putting out 1700 crankshaft HP per unit. 

You have evidently made the mistake a lot of folks make; somebody tells you he's an N&W man and you assume that everything that comes out of his mouth is Gospel.  I'm no different.  You don't have to believe a thing I write, but you can check it out; I invite you to.

Now, Mark S, you seem to have not absorbed what I explained earlier about N&W's 2100 and its horsepower output relative to its boiler and firebox size, so I'll explain it yet again.  The Y-6 was a COMPOUND.  It fed throttle steam into a pair of 25-inch cylinders which exhausted into a pair of 39-inchers where it was expanded again.  Both sets of cylinders contributed to the DBHP figure, just as if they were on a simple engine.  Therefore, its 4-8-4-sized boiler could produce adequate steam which, used twice instead of just once, could in turn produce that 5,500 drawbar horsepower required to lift 10,000 tons up an 0.2% grade at more than 30 MPH.  Bob Pilcher, BTW, was responsible for many of the features of the 2100 that enabled it to perform that well.

I also see the name of my friend Bob Le Massena (a Mechanical Engineer) invoked.  There's an interesting anecdote about Bob.  The N&W tested A 1210 on coal trains between Williamson and Portsmouth in the mid-1940s.  Tests of A 1239 in the diesel comparisons of 1952 showed an increase in performance (GTM/TH) of eleven percent over what the 1210 did.  Bob Le M., being an ME, just KNEW that there had to be some difference in the 1239 that allowed it to perform 11% better.  There wasn't any difference.  In the intervening years there were many improvements in freight car trucks, journal bearings, wheels, track structure and the like that made 1952 cars easier to pull than 1944 cars - in other words, resistance per ton was less.  But Bob wouldn't believe it.  He insisted that the 1239 had altered cutoff and the boiler pressure was raised to 315 pounds, etc.  A friend of mine, Louis Newton (a mechanical engineer, since it's important to you) was a Special Apprentice in the Mechanical Department and rode the 1239 during those tests.  There was no difference with the engine (the 1239 had the roller-bearing rods and the 1210 did not, and also had an auxiliary tender which enabled the run to be made non-stop, but that was far short of being 11% worth).  Le Massena wrote the "A-1/Y-6c" story (Y-6b 2195 had been similarly tested against the F7 between Williamson and Bluefield and Bob insisted that it had the same alterations) up in TRAINS magazine.  Newton produced a cogent rebuttal in a letter to the editor which blew Bob's theory away.  The proof of the pudding was the fact that after the 1239 test, tonnages were increased on coal trains between Williamson and Portsmouth and every A in the pool started handling the heavier trains in the same time frames that the 1239 had.  Now, if you think they could have raised the pressure to 315 and had the gauges set for 300 and not had anybody find out about it, I've got some swamp lots not too far from here I'd like to sell you.

5432, what's it going to take for Feltonhill to convince you about the evaporation rates?  He's tried and tried, and you keep ignoring the facts . . .  

EdKing

That must be the metric equivalent to "ergs per kumquat".

EdKing

none of which answered my theroetical question of how many passenger cars a little NKP Hudson could possibly pull up the Gorge....

 

Steam Fan

I'll take a semi educated guess at it.

The NKP Hudsons were very light.  At best they could handle about 3/4s of the train that NKP 765 could.  That would put it at about 22 cars, a very respectable passenger train.

With heavy weight cars a Pacific or a Hudson would be limited to about 5 cars on a 2% grade, and about double that on a 1% grade and double that again on a 0.5% grade.  If the grades on the New River are about 0.5% that would be about 20 cars, in the range with 3/4 of what NKP 765 has pulled.

The units of the Watt are Newtons, meters, and seconds.

WBC

You can use Newtons, meters and second to get Watts and divide by 746 to calculate Horse Power if you want.

The rest of us are using units of pounds, feet and seconds or pounds, miles and hours and get to Horse Power more directly.  That does not mean they are being used without care.

The distance and force units may be different but the power measured is the same.  Living in the horse power capital of the world very few of us think of power in terms of how may light bulbs our car, truck or locomotive could light up.

For instance, I remember a post that went something like this: 765 is pulling a 30 car passenger train in tandem with a diesel locomotive of similar horsepower. The throttle of the 765 is throttled into such a position so its net force on the train is zero and only the diesel was doing the work. The result was the diesel could only go 30 mph with the 30 car passenger train. However, 765 by itself could pull the train 60 mph (maybe in the 50’s but I am making the math easier).  Here are two supposedly equal power machines with one (the steam locomotive) seemingly doing a vastly superior job. In this case it would be true, by the definition of the Watt; the steam locomotive is doing twice the amount of work.  While not explicitly stated, it was certainly suggested as to which machine was superior.

I believe you are recalling a Railfan magazine article written by Rich Melvin.  If I recall correctly Rich had a 3000 HP Diesel.  It could out accelerate the 765 with the train at speeds below 30 mph because the Diesel-Electric could run the diesel engine at full power while taking advantage of the low speed torque advantage of electric traction motors. A steam locomotive has limited horse power generating capacity at low speed due to the low number of power impulses created by its direct drive reciprocating engine at low RPM.  Once the 765 got to higher speed, about 30 mph in this instance, it could generate more horse power than the 3000 HP diesel.  It the Diesel were a SD70 or ES44 the diesel would have an even greater advantage at low speed and closely match the Berkshire's performance at higher speeds.

That is why today's diesel-electrics are such fantastic locomotives.  They all have the low speed tractive effort of an articulated and the horse power available at 40, 50, 60 or even 70 MPH to match many Berkshires or Northerns.  They are very versatile machines. 

Ed, as a huge N&W fan I must say that the information you provide is truely appreciated....I love learning all I can...doesn't matter if it's about the A's, Y's, J's,K's or M's  Thank you for taking the time to provide it.

I apologize for not articulating my self well. That is not what I intended. Certainly the Watt can be expressed in in Old English units. The only thing I would change in your post would be foot-pounds in place of pounds since foot-pounds is force in the English system. However, be the units in N m/s or lbf/s, it is still the Watt.

Naturally the blanket statement that horsepower equals speed has troubled me since there are so many global examples where the statement is not applicable. However, in railroading terms, the opposing force is not a free variable. It is fixed. For instance, compare an AC4400CW with an AC6000CW.  These locomotives are nearly the same size and weight. Thus, the opposing force on the locomotives is very similar. 

Using the definition of a Watt and horsepower it can be figured that an AC4400CW can hold a velocity of one meter per second with an opposing force of 3282400 Newtons. You can put it into feet per second foot-pounds, its still the same.

However, the AC6000CW is limited to an opposing force of 3282400 Newtons due to physical constraints. Thus, the extra 1600 horsepower can be used to increase velocity. Thus, the AC6000CW can hold a constant velocity of 1.36 meters per second against an opposing force of 3282400 Newtons.

In short, the AC4000CW has a velocity of 1 meter per second while the AC6000CW has a velocity of 1.36 meters per second with the same opposing force.

Thus, under the limiting constraints of the system, more horsepower equals more speed as Mr. Melvin says.

But this is not true in a global sense.

Sorry for going so far off tangent in this thread.

Ed King: I ask this question not in an argumetative spirit and fully stipulate that your knowledge of the Norfolk & Western exceeds my tenuous grasp by many meters (!), but how does compounding add to horsepower? It adds to fuel consumption efficiency, certainly, by extracting more work from each BTU expended. The Y6's had, if my understanding is correct, an "intercepting valve" that allowed a shot of fresh, dry steam to be shot in the compound cylinder; now that strikes me as able to boost horsepower. Additionally, the A's had a larger grate area and a much larger evaporative surface then a Y - would that not produce a greater power output, hence justifying a 6300 DBHP reading? Also, the A's handled 14,000-14,500 ton coal trains at 40 mph between Williamson, WV and Columbus, OH - solo. I observe daily UP coal trains of something approximateing 14,500 tons being pulled/pushed by 13,200 diesel horsepower. 6300 horsepower makes sense to my perhaps naive sensibility.

Thanks, Ted. Thats about what I had figured as well. The NKP Hudson appears, by statistics, to be about 2/3 or 3/4 of a Berk, so I had guessed myself that it would be able to take close to 20 cars up it.

Mr. King, I appreciate you loading the threads up with N&W facts, I would have loved to live back when steam was "king" (pun intended.. LOL)  I have your book on the "A"s, I do have one question about the boiler explosion on 1204 when it wrecked and overturned. 

 How would putting on the injector cause the boiler to explode... if the engine/tender is on it's side, in my mind there's no water available to be picked up to be injected...

Thanks,

Dave

The reason the A had the larger firebox and boiler was to make the locomotive able to handle the Y-6 tonnage at much higher speed; indeed, considerably more tonnage at higher speeds on more level trackage.  The 4-8-4 sized boiler wouldn't get that job done. 

Ed: Aren't you making my point here? The A took the same tonnage handled by the Y and hauled it faster.......and per Rich's point, speed requires more horsepower. Could it be that the dynamometer reading you quote was taken lower on the A's power curve? Doing a quick back of envelope calculation, the A's grate area was 14.8% greater then the Y's. And guess what (I was surprised by this)? The 6300 DBHP reading is 14.55% greater then the 5500 DBHP rating you have cited for the Y. It would just defy logic that a boiler with a larger grate area and evaporative surface (and equal boiler pressure) would not produce more power. Why do I yammer on about grate area? That is where the energy contained in the coal is transferred to the water being boiled......more grate = more boiled water = more steam = more power. I take nothing away from the Y and the J; they were GREAT locomotives! Just don't want to see the magnificent A get short changed!

I think this statement is incorrect (or perhaps I'm just mis-understanding). "Heating surface" is where "the energy contained in the coal is transfered to the water," and is far larger than just the grate area.