CSSHEGEWISCHWhile I will concede that no single unit can match the performance of a single Challenger...
While I will concede that no single unit can match the performance of a single Challenger...
You do bring up good point about the MU ability of diesel-electrics. If it was possible for the railroads to MU steam engines under one crew, the development of the steam locomotive would have stopped with the 4-8-2 Mountain locomotive. A pair of good 4-8-2s will out perform any single large articulated ever made.
While I will concede that no single unit can match the performance of a single Challenger, the miracle of multiple unit control will allow enough units to be combined as a single locomotive to equal or exceed the performance of said Challenger, Big Boy, Allegheny, EM-1, Y-6b, etc. And unlike those steam locomotives, a multiple-unit diesel locomotive can be taken apart and put back together at a different rating to match the train to which it is assigned.
While checking my archives I remembered there was quite a bit of information recorded on the performance of the Allegheny 2-6-6-6's.Some of the biggest and most powerfull locomotives ever constructed.According to the book "The Allegheny Lima's finest by Eugene huddleston,1984"....
Allegheny #1608 estalished a all time drawbar horsepower record of 7,498hp with 14,075 tons at a speed of 46 miles per hour.Official records site 160 cars plus caboose and dynameter care with 14,075 tons.
In another test the 1608 climbed a .7% grade with 160 loads weighing 14,083 tons at a speed of 13 1/2 miles per hour.It soon accelerated to approx. 24mph and maintained this speed to the top of the grade .2% most of the way.
In 1951 they conducted tests with a new type of exhaust nozzle.They tested the Allegheny at a dead stop at the foot of a .30% grade first with 145 cars(12,284 tons) a second with 146 cars(11,620 tons)and a third with 153 cars(12,301 tons)and each time they had no difficulty starting the train up the grade.They maintained a average speed of 18 to 20 mph up the grade.
On the Virginian railroad the H-8's hauled 13,500 tons on a .20% grade on a regular basis.
We can debate friction vs roller bearings,factors of adhesion,horsepower and tractive effort,but all we really need to do is put a locomotive on a train of a certain weight and see if I can pull it.We know you can get a the correct weight of a railcar by weighing it on a scale.No matter what way you look at it a 14,000 ton train yesterday would still be 14,000 ton train today.My argument that there is no way a single modern day locomotive could pull anything close to what one of these massive steam locomotives used to despite what the horsepower and tractive effort claims to be.I know from my days as a conductor for the Union pacific there is no way in hell you can pull a 14,000 ton train up any sort of grade with a single locomotive.I doubt you could even pull a 14,000 ton train at all even on a flat grade.
In attempting to understand locomotive data from 60 years or more ago (19 years before I was born), one of the very common issues is that it seems the railroads were too busy running their business to go back and do tests on the "improved" versions of their finest locomotive models.
Though UP did indeed perform all kinds of tests on their 4-12-2's and 4-6-6-4's as the years passed, for whatever reason, it appears we do not have any records of either improved tractive effort curves or improved horsepower curves available to us today (at least none that I'm aware of).
Also, in the case of N&W, at least Y6B #2197 received some additional improvements for a test against diesels (some of which may have been applied to other engines), and claims of 170,000 pounds starting tractive effort have been made. Yet at the same time, the "official" or "reported" starting tractive effort of 152,206 appears to have not ever been revised. Various books and websites I've read all seem to question the 170,000 pound figure for the "Improved" Y6B.
I wish we had more information than what apparently survives.
Unfortunately, for some roads (like Rio Grande) the officials at the top tried consciously to get rid of everything that had anything to do with steam power. So surviving records are extremely limited, and this makes it difficult even to produce an accurate model of their steam (without excessive scaling from photographs). I've been told but cannot confirm that what few drawings do remain in the Denver Public Library can end up costing $100 or more per page for them to dig them out and copy.
John
samfp1943Here is a video of the 1218 in Apr 87. What is amazing is the size of the passenger train (I'm guessing; about 20 or so cars), Maybe some one can get a better count. Anyway there is a segment of the 1218 slipping on Christianburg Hill near Arthur,Va. Slipped 3 times in starting that train on the grade...Anyone provide what percentage that grade is? Thanks!
Here is a video of the 1218 in Apr 87. What is amazing is the size of the passenger train (I'm guessing; about 20 or so cars), Maybe some one can get a better count. Anyway there is a segment of the 1218 slipping on Christianburg Hill near Arthur,Va. Slipped 3 times in starting that train on the grade...Anyone provide what percentage that grade is? Thanks!
Here's something I found on google videos: The 2101 climbing the B&O's infamous 17 Mile Grade with an excursion train. That grade is an operational nightmare, climbing straight up the Allegheny Front on a maximum 2.69% grade. Video is not the best quality, but still impressive.
http://video.google.com/videoplay?docid=-2497140354363120108#
Thomas 9011This is a interesting topic.I have always said despite what these new locomotives claim for horsepower and tractive effort they can still not do what the steam locomotives could do with a single engine.You could pick any locomotive out there and there is no way you are going to pull 140 cars at 30 or 40mph with a single modern day locomotive no matter what the claims. I was told by someone once that a steam locomotive has unlimited horsepower.As long as you could produce enough steam you would basically have a locomotive that could keep pulling harder and harder as long as you could keep up with the steam supply or until the wheels started slipping.Many engineers and locomotive designers claimed the Allegeheny could produce a unheard of amount of horsepower if there was someway possible to keep the massive amount of steam going to the cylinders.Of course they never tried this expierment as you would have to have probably double the amount of fire and double the amount of water to keep the steam at the boiler maxium pressure,going full throttle,with maxium load.I can only assume you would burn through all your fuel and water in a very short time if you were going to try this(much like a truck driver trying to go up a steep hill at 75 mph with a full load). The only disadvantage the steam locomotives had is their huge drive wheels.It was like starting a car in high gear.Diesels have small drivers so their HP and TE if very impressive.They call pull very heavy trains at low speeds.Steam locomotives with their high wheels are better at higher speeds as the sheer size of their wheels covers alot of ground with just a few strokes of the piston.Had the big boy locomotives had 36" wheels I can only imagine it would have at least 10,000 horsepower or more.
This is a interesting topic.I have always said despite what these new locomotives claim for horsepower and tractive effort they can still not do what the steam locomotives could do with a single engine.You could pick any locomotive out there and there is no way you are going to pull 140 cars at 30 or 40mph with a single modern day locomotive no matter what the claims.
I was told by someone once that a steam locomotive has unlimited horsepower.As long as you could produce enough steam you would basically have a locomotive that could keep pulling harder and harder as long as you could keep up with the steam supply or until the wheels started slipping.Many engineers and locomotive designers claimed the Allegeheny could produce a unheard of amount of horsepower if there was someway possible to keep the massive amount of steam going to the cylinders.Of course they never tried this expierment as you would have to have probably double the amount of fire and double the amount of water to keep the steam at the boiler maxium pressure,going full throttle,with maxium load.I can only assume you would burn through all your fuel and water in a very short time if you were going to try this(much like a truck driver trying to go up a steep hill at 75 mph with a full load).
The only disadvantage the steam locomotives had is their huge drive wheels.It was like starting a car in high gear.Diesels have small drivers so their HP and TE if very impressive.They call pull very heavy trains at low speeds.Steam locomotives with their high wheels are better at higher speeds as the sheer size of their wheels covers alot of ground with just a few strokes of the piston.Had the big boy locomotives had 36" wheels I can only imagine it would have at least 10,000 horsepower or more.
What????
oltmannd feltonhillTractive Effort x speed/375 = Indicated HP A bit off topic, but wouldn't the indicated HP be calculated from the PV diagram traced out by a cylinder indicator?
feltonhillTractive Effort x speed/375 = Indicated HP
feltonhill TE x Speed/375 is not a measure of DBHP. It's a measure of Indicated or cylinder HP. Tractive effort is not measured at the drawbar. Drawbar pull is measured at the rear of the tender. This is where the dynamometer car is located during road tests. Therefore, DBHP is calculated from tractive effort/force less the machinery resistance of the locomotive minus the rolling resistance of the locomotive and tender minus the air resistance of the locomotive. IHP is measured by indicator diagrams taken from measurements at the cylinders and converted to IHP by use of a planimeter. This agrees in large part with earlier posts.
TE x Speed/375 is not a measure of DBHP. It's a measure of Indicated or cylinder HP. Tractive effort is not measured at the drawbar. Drawbar pull is measured at the rear of the tender. This is where the dynamometer car is located during road tests. Therefore, DBHP is calculated from tractive effort/force less the machinery resistance of the locomotive minus the rolling resistance of the locomotive and tender minus the air resistance of the locomotive. IHP is measured by indicator diagrams taken from measurements at the cylinders and converted to IHP by use of a planimeter.
This agrees in large part with earlier posts.
TE x Speed/375 is not a measure of indicated HP either. The HP determined from the indicator diagram is the work applied to the cylinder faces, and that gets diminished by the friction of the cylinders, crossheads, connecting rods, and wheel bearings before it gets to the wheel surfaces.
If GM "killed the electric car", what am I doing standing next to an EV-1, a half a block from the WSOR tracks?
selectorThis is diverging from the point, but I am amazed at this comparatively small engine. If current HO models are accurately rendered, it was much smaller an engine than an H-8 or a Yellowstone, for example, but it out-performed them in terms of brute traction at start-up. -Crandell
This is diverging from the point, but I am amazed at this comparatively small engine. If current HO models are accurately rendered, it was much smaller an engine than an H-8 or a Yellowstone, for example, but it out-performed them in terms of brute traction at start-up.
-Crandell
With the 2-8-8-4s, one could make an argument that the DM&IR did not utilize them to their fullest extent (e.g. lugging around ore trains at relatively slow speed) while the B&O did (not only in coal service, but full use in high speed general merchandise trains and high speed express service). The 2-8-8-4 was the perfect locomotive for the B&O's high speed main lines, while the DM&IR might have been better served with a version of the Y6b.
oltmanndfeltonhillTractive Effort x speed/375 = Indicated HP A bit off topic, but wouldn't the indicated HP be calculated from the PV diagram traced out by a cylinder indicator?
Tractive Effort X speed/375 would be a measure of drawbar HP, provided that tractive effort is measured at some drawbar. Indicated HP is indeed defined as the "fatness" of the cylinder indicator curve. Indicated HP is always greater than drawbar HP because of the friction losses in the cylinders, valves, valve gear, rod bearings, wheel bearings, and even the aerodynamic drag of the locomotive.
The indicated HP is some measure of the thermodynamic efficiency of the engine, that is the efficiency of turning steam at the operating pressure and superheat temperature into mechanical work at the piston faces. Indicated HP does not take into account the efficiency of combustion or the efficiency of heat transfer in turning coal into steam, and it does not take into account the mechanical friction losses downstream of the piston faces.
-Don (Random stuff, mostly about trains - what else? http://blerfblog.blogspot.com/)
A Y6b if held in simple operation at 5 mph will develop about 155,000 lbs drawbar pull based on curves developed from road tests. At this, reading, about 2,070 DBHP is being developed. So your figure is about right. However, the DBHP curve rapidly increased to 3,200 at 10 mph, 5,200 at 20 mph and a max of 5,500 at 25 mph. These latter figures are in compound operation.
In compound operation at 5 mph, the Y6b (and the improved Y5/Y6's) developed about 130,000 lbs DB pull, or 1,700 DBHP
UP 4-12-2 Y6B in compound mode: 152206 pounds TE X say 5 mph divided by 375 = 2094 horsepower Just sounds a bit low to me.
152206 pounds TE X say 5 mph divided by 375 = 2094 horsepower
Just sounds a bit low to me.
"Horsepower" doesn't have any independent existence-- the force-times-speed-div-by-375 formula defines it. You measure force and calculate horsepower.
I'm well out of my depth, but I always understood HP as being a force moving, but also sustaining, the mass at a given speed. Tractive effort is more related to torque applied somewhere along the drivetrain, say at the axles, or a driveshaft. Low speeds are where the torque comes into play, but it falls off rapidly as a HP curve climbs, and that would necessarily mean a steam locomotive develops its useful HP at speeds, often in excess of 40 mph. So, I wouldn't expect a Y to be producing much more than 1500-2000 hp below 6-8 mph.
The formulas might be correct, but I think someone above was taking starting tractive effort and attempting to convert it to maximum horsepower, which you cannot do. Also, in the real world, and as you indicated in your comments regarding indicated horsepower at the cylinders versus drawbar horsepower, there are other variables and losses that come into play. If the engine wasn't being fired correctly, or wasn't working flat out at the maximum output, you get misleading data.
I agree--without having the actual tractive effort curve value for a given speed, you cannot calculate drawbar horsepower correctly.
I sold both volumes of the 4-12-2 books by Kratville and Bush, so I no longer have those curves for that engine--but at 37 mph, tractive effort has fallen off considerably from the peak.
I don't believe Kratville gives the tractive effort curve of a Challenger--at least not in my 1980 edition of his book.
Y6B in compound mode:
Just sounds a bit low to me. Is it correct? Maybe, but I honestly have no idea.
UP 4-12-2 - The formulas
Tractive Effort x speed/375 = Indicated HP
and
Drawbar Pull x Speed/375 = Drawbar HP
aren't estimates. They are mathematical relationships. TE and DB Pull may be estimates, but the formulas are accurate if the input variables are accurate. If this isn't the case I'd like to see an example. I've been working with locomotive performance for over 40 years, and I've never seen a case there these two relationships were proved incorrect.
Also, what kind of horsepower are you referring to, indicated or drawbar.? With steam locos, using the word horsepower without an adjective doesn't mean much. Kratville refers to 5,400 maximum cylinder HP for the 3900s (p127) which is the same as indicated HP, so he's specific as far as type of HP. The estimate I gave earlier of about 4,700 DBHP at 40 mph also showed 5,500 IHP at the same speed. That's one of the reasons I felt OK in posting it because it tied into Kratville's figure.
Also--it was customary on the old railroad plans to quote degrees of curvature. This really had to be degrees of central angle, and not the civil engineering definition of degree of curve.
As already pointed out above, the math just doesn't work out--those old track charts are stating degrees of central angle.
John (civil engineer)
While there is a mathematical approximation between horsepower and tractive effort, it does not hold in real life actual performance.
Tractive Effort, more correctly known as Starting Tractive Effort, does not remain constant, but immediately drops off for most engines after about 10 mph.
Locomotive horsepower curves are bell shaped, and for steamers, generally increasing as speed increases (and different from diesel horsepower curves).
That's why diesels can start a train they cannot keep moving on some grades (and stall), and steamers can pull more train than they can start (helpers were used on long trains on the PRR just to get them rolling).
The Union Pacific 4-12-2 produced 4917 horsepower at 37 mph as originally tested during 1926.
The Union Pacific Challenger was designed to exceed that power output and run as fast as 90 mph.
Kratville in The Challenger Locomotives says they were designing for about 5500 horsepower. IIRC, the actual drawbar horsepower was said to be in the 5200 horsepower range.
Starting tractive effort was not important to the Union Pacific. Instead, horsepower at speed was--and they really wanted high speed, because they were in a race with Santa Fe and others to see who could move freight the fastest.
Also--today's diesels are using computerized wheelslip control to maintain a much more constant (and higher) rate of adhesion between the steel wheel and the rail than what steam power could achieve. As much as I love steam power, there is no real comparison to today's diesels. They're just different animals.
Most of the action was filmed on Blue Ridge grade east of Boaz (the natives tell me it's pronounced boze, not bow-az) siding near Vinton, VA. The sample on youtube was made as the train approached "photographers bridge" about halfway up the hill. The bridge is long gone and the area has grown over considerably since 1957. I just bought the DVD in Roanoke last weekend, and it's probably one of the best I've ever seen.
A train weight of about 11,000 to 12,000 trailing tons sticks in my mind if three loco's were used, but I'm not sure.
samfp1943 And just for good measure Two Y's hauling 174 loads, Awsome!
And just for good measure Two Y's hauling 174 loads, Awsome!
Your link was incorrect. Perhaps you meant this link:
http://www.youtube.com/watch?v=zV8rA3UE-lc&feature=related
Hey feltonhill, any idea where this was filmed at? Also, can you estimate the weight of the train based on the capacity of the N&W coal cars at that time?
It seems you have copied the same URL. ?
jr 611 good video but have you seen N&W #1218 + 100 Coal Hoppers (1987)
For Comparison, and because you mentioned and I had not see it; I looked it up and linked it here;
http://www.youtube.com/watch?v=pl-QVxHIq6o
Edit:
http://www.youtube.com/watch?v=so7-Fu2psjc&feature=related
CAZEPHYR.It did slow down for sure on the grade, but take note, five GE's had pulled the train into Cheyenne from the west. This was back in 1993 I believe so those units would have been 8-40CW's most likely. CZ
.It did slow down for sure on the grade, but take note, five GE's had pulled the train into Cheyenne from the west. This was back in 1993 I believe so those units would have been 8-40CW's most likely.
CZ
Paul_D_North_Jr For a fictitious example, if 3985 was producing 95,000 lbs. TE - per GP40-2's post on the previous page of this thread - at 20 MPH, that would be about 5,070 HP. But if at 40 MPH it was only producing 50,000 lbs. TE, the 'stack talk' might be considerably less - but the HP output would be close to 5,335. ...
For a fictitious example, if 3985 was producing 95,000 lbs. TE - per GP40-2's post on the previous page of this thread - at 20 MPH, that would be about 5,070 HP. But if at 40 MPH it was only producing 50,000 lbs. TE, the 'stack talk' might be considerably less - but the HP output would be close to 5,335. ...
selector it seems steeper than a mere .7%.
selector the S-curve...would this not impose a substantial impediment to the climb up the grade, say by adding about 0.2%
Paul_D_North_Jr something's wrong with that curvature figure
To compute an average compensated grade over the 2.7-mile climb, we don't need to know how sharp the curves are (assuming we're making the usual assumption that curve resistance is directly proportional to curve sharpness). If we make the usual assumption that a 1-degree curve is equivalent to 0.04% upgrade, and sharper curves proportionately more, then 98 degrees of total angle is equivalent to 3.92 feet of altitude gain, which we add to the actual altitude gain to get the average compensated grade over the 2.7 miles.
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