Allegheny Tractive Effort Table

[Anonymous]

@timz and BigJim

thank you for extensively answering my questions and showing more facts for the Y6.

Can we draw following conclusion: at a ruling grade of ~1% ratings for Y6 was 5200tons and at ~1.2% it was 4600tons ?

 

 

[selector]

So, let's suppose a bystander uses his dusty boot toe and slides the representation of a Z-1 into the circle.  Does this add more worms to the can?

[timz]

once all of that tonnage was on the grade it was dead weight no matter if it be three, five, ten or 25 miles long.

Agreed, the weight never springs to life. Question is, how much of Blue Ridge was 1.2% and not 1.1%? That problem doesn't arise (not so much, anyway) with the climb to Christiansburg. Or with the eastward climb to the Elkhorn tunnel, after 1950.

BTW, the Y6 had 58" drivers, not 57".

Lessee-- the Y5 had 57" as built, and the Y6-- probably the Y6a too? For all I know they all ended up with 58 inches, but the TE calculation was made when they still had 57 and was never updated.

[BigJim]

Ogden - Wasatch

Ruling grade 1.14%

What is the grade on Blue Ridge?

Ruling grade 1.2%

Lars,
   Let's look at the facts as given in William Kratville's book "Big Boy". There were three tests of the Big Boys. Trains of 3479 tons, 3883 tons and 3539 tons. Average speed from Echo to Wahsatch, all up hill and mostly 1.14% grade, was respectively 14.6 mph, 14.8 mph and 17.4 mph. After the tests, tonnage ratings were readjusted. Designed for 3600 tons, they were regulary given 4200 tons. In the final steam years they were rated at 4450 tons.
   This compares to the 4600 tons for the Y6 on the 1.2% grade of Blue Ridge. Mr. Timz seems to make light of the Blue Ridge's 1.2%, but remember, we are trying to make a comparision as closely as possible. As famous as the Blue Ridge grade has become over the years, there were heavier grades going North, South and West out of Roanoke. Timz' Christiansburg grade pales in comparision to the 25 miles of grade from Glyn Lyn into Bluefield. Also keep in mind that once all of that tonnage was on the grade it was dead weight no matter if it be three, five, ten or 25 miles long.
   If you must fixate on tractive effort ratings, the N&W never published a TE rating after the Y6 locos were improved and weight was added to the front engine frames. One can only guess. I'll say this, tonnage ratings for the "Improved Y6" (that is what they were referred to by the N&W) jumped an average of 500 tons per district. I'll let you lads do the math.
   Now, let's deal with Mr. Le Massena. Mr. Le Massena has been very kind in his writings of the N&W locomotives. However, since the Steam vs. Diesel tests, he has been consumed in the assumption that there were "ringers" involved in the tests. He contends that there was a "Super Class A" and "Super Y6". This myth has been shot down by people that were intimately involved in the tests. The Class A's and Y6's were all super, without having to cheat. I don't believe the 190,000 lb. figure to be very accurate.
   Let's clear up the simple and compound operation. Simple operation, if needed, could be used up to about 15mph, after which compound operation was used. If tonnage didn't require starting in simple, compound was used. There was a sort of "booster" valve that could also be used up to about 15 mph that added a little more power while in compound.
   In this narrative I have referred only to the Y6. This class includes all of the Y6, Y6a and Y6b locos and along with the Y5 class after the improvements, all were basically the same. 
   BTW, the Y6 had 58" drivers, not 57".

With all of this said, I'll politely bow out and let the number crunchers continue.

[timz]

The highest starting tractive effort from a successful, regular production steam-piston locomotive was, IIRC, about 176,000 lb from the Virginian XA 2-10-10-2's.

ALCo claimed 176,600 lb simple from the 2-10+10-2; dunno what formula they used to get that-- just something empirical, I assume. If you use the same formula that N&W used you get 135,200 lb in compound and 162,200 lb simple.

Note they supposedly had 617,000 lb on drivers, only a bit more than the N&W engines had after they got their extra weight, after 1950 (?). 

[timz]

What is the grade at Blue Ridge, and how long is it?

The Blue Ridge grade doesn't have any settled value-- it varies, with the maximum being something over 1%, maybe as much as 1.2%. But don't bother with Blue Ridge-- anything you read about a performance there isn't much help, since you don't know what the exact grade at that location was. Instead look at the climb from Walton to Christiansburg, which stays pretty close to 1.0% compensated for six miles. Final Y5/Y6 rating there was 5150 tons of slow freight.

So what TE would it take to start a 5150-ton train that happened to get stopped on the 1%? We don't have much idea-- nobody knows exactly how much TE it took to start a friction-bearing train. Maybe 125,000 lb was enough, but for all we know maybe they'd need 140,000 lb or more. So could they reliably start a 5150-ton train that got stopped on the 1%? We don't know that either. 

However, builders specified starting TE was just 152.000 (simple) and 126.000lbs in compound mode.

That's the nominal (i.e. calculated) TE; we don't have much idea how realistic it is. Here's how they calculated it.

You know the usual formula for a two-cylinder engine: you assume the mean effective pressure in the cylinder is 85% of the boiler pressure, and you assume that the total work done by that pressure, acting on the piston of known diameter, through a known stroke, is equal to the work done at the rim the driver of known diameter during half a revolution. Run thru the algebra and the two pi's cancel out, so you're left with

nominal TE = 0.85 x pressure x bore squared x stroke, divided by driver diameter

(Yeah, I knew you'd notice: the thrust on the back of the piston is less than on the front, since the piston rod cuts the effective area. Apparently that factor is included in the 0.85.) 

Dunno how many formulas there are for compounds, but N&W used the simplest one, assuming that the total of the MEPs in the high- and low-pressure cylinders was the usual 85% of boiler pressure, and assuming that in compound the TEs of the two engines should be equal. In other words (since the Y6's LP piston area is 2.4336 times as large as the HP) the MEP in the HP cylinder should be 2.4336 times the MEP in the LP cylinder, and the two MEPs should add up to (0.85 x 300) = 255.

Do the algebra and you get LP MEP = 74.266076. We use that in the usual way to get the TE for the LP engine: 63415.4 lb. We're assuming HP TE is the same, so total for the whole engine is 126,830.8. Apparently a typo converted that to 126,838 which is the figure usually given for the Y5/Y6. How do they get simple TE? Multiply by 1.2. Why 1.2? Nobody knows, but 1.2 times 126,838 gives the usual 152,206.

That's for a 57-inch driver engine, not a 58-inch. 

[Anonymous]

Who wouldn't like to see hers/his favorite steamer see run. again? Still after 60 years they are fascinating, thank you for sharing thoughts...

[Anonymous]

Im not sure, you might want to search Dynometer car data through the historical society.

Tell a steam engineer "Your choo choo aint got the...."

and watch him go to it.

[Anonymous]

@dredmann
That's the problem with sources: It's from "Joe G. Colias" "Big Boy&Co.". It is written before the final last years of steam and really nice. Yet, he appears more an author to me, than a technician.

To quote you: "whether there was some problem that essentially prohibited simple operation at more than a few mph, or there was a problem generating enough steam to keep up with the demands of those big front cylinders, if you feed them with high-pressure steam directly from the boiler"

We can exclude that, right?

How about 2 lines for the Y6 on the table: TE at simple at full speed range and one of compound?

Can somebody tell us?

lars

[dredmann]

P.S.

The only steam-piston locomotives that had tractive efforts in the 190,000 lb range were experimental, and basically failures: some of the triplexes. The highest starting tractive effort from a successful, regular production steam-piston locomotive was, IIRC, about 176,000 lb from the Virginian XA 2-10-10-2's.

 

[dredmann]

Lars, if the graph you are looking at for the Y6b indicates a starting tractive effort of 170,000 lbs, then that at least purports to reflect their final form. (By the way, most if not all of the Y5 and Y6 class locomotives eventually got most if not all of the improvements.) If it falls as far as 125,000 lbs at 10 mph, then to me that suggests either pure compound operation, or at least basically compound operation with just a little boost from the somewhat complex N&W system.

Frankly I would be somewhat surprised that a y6b's tractive effort would fall so far at such a low speed. I am not sure whether there was some problem that essentially prohibited simple operation at more than a few mph, or there was a problem generating enough steam to keep up with the demands of those big front cylinders, if you feed them with high-pressure steam directly from the boiler (instead of mostly once-expanded steam from the rear, high-pressure cylinders).

Generally, I think we can say three things with a high degree of confidence: (1) the Big Boy was much more of a high-speed design than the Y6b, and could run faster; (2) the Y6b could start, and pull at low speeds, a considerably heavier train than a Big Boy could; and (3) a Y6b can pull a train fairly fast (50+ mph), but is outside of its design envelope at 60+ mph.

 

[Anonymous]

First of all, thank you Everybody for putting more info here!

@BigJim:

What is the grade at Blue Ridge, and how long is it? Do not have any sources for that, only for Sherman and Wasatch. However, if train speeds exceeds 10mph, both should have the ability to haul same weight . 3250 tons is not bad, maybe Y6 or some other could pull some more, but their TE-Table does not show it that clearly ( I only can rely to this, sorry for being blind on one eye! ) Most would pull far less. A "H7" was rated 2400tons, a Challenger 2100tons. 

To be honest, I am little bit confused on Y6 datas, you can help me for sure: I only have the TE-Table for the Y6, which Railway Man posted earlier on this thread, though I read higher values. The graph compares an "A", a "Y6b" with "Jawn Henry". It is likely therefore, it relates to the later, refined Y6b. It starts with 170.000lbs, and drops to 125.000@10mph. After it it smoothes down:100.000@20, 65000@30. Guess this is all simple expansion. Compound would lower the TE-Curve, right? However, builders specified starting TE was just 152.000 (simple) and 126.000lbs in compound mode. Read once, they had something around 190.000lbs (Massena's, Kings's thoughts?). Which one is true? And, the Y6 had certainly the abilities to run more than 50mph (short time?), but based on a day-in day-out schedule or at a 100mile run? Do not think it is a good idea. Maybe the later, refined Y6b could do so?

@VAPEURCHAPELON:

I totally agree with you the N&W engines would not run out of steam at all but it would affect engines permormance: Reading your post, can we conclude, a given firebox, mated with an appropriate boiler, will always deliver a certain output until its max. is reached? And only the firing rate varies? Confuses me, 'cause weren't oil-burners in general more powerful? I think about the German post-war DB01, DB45, ... classes, the difference between coal and oil was ~200hp on these 2000hp engines. Is that caused from heat content of oil, or do other things play a role? However, 200hp more or less for a 5000-6000hp class engine would a be small percentage, but 10%?

Looking forward for Your answers!

lars

P.S:

You may find the graph at http://locofonic.alphalink.com.au/te1.htm

 

[switch7frg]

   To all who posted yesterday & today :  this thread has been very informative . One would say all the engines did their job as desined,subject to the whims of the engineer and all the variables at hand. 

                 Thanks to all of you. Respectfully , Cannonball ( another Jim)

[VAPEURCHAPELON]

I think on a performance level, they could do any job, but few engines could do the job of BB..... And could haul 3250t@1.55% at 15-20mph

Over the Blue Ridge grade, which would be very similar, the Y6 was rated at 4600 tons in slow freight and 4100 tons in time freight service.

50 -55 mph speeds on a Y6 were not uncommon. As a steam engineer related to me, 63 mph was about as fast as you wanted to run a Y6. After that things started to get a little shaky. So the problem a Y6 would have would have in keeping up with a Big Boy would be more from the inherent dynamic forces and speeds in the running gear brought on by the smaller drivers.

As for running out of steam, with good coal, N&W's big three had no problem with steam production. Engineers have also told me that even in simple, the Y6 had no problem keeping a full gauge of steam and could even lift the pops.

Too bad Road & Track magazine didn't do performance tests (like they did with the Strasburg Decapod one April) on steam locos when they ruled the rails.

Jim, have many thanks for this nice posting. Thanks to feltonhill, too.

Please let me throw in another thing: I guess it's sure that N&W's great three steamers even could put out the same amount of steam and therefore hp with fuel of lesser quality than they actually used. They may have needed more fuel then, of course. But firebox volume and grates were very large on all three designs, it's simply unlikely that there would have been steaming problems. Maybe that would have required other grate bars and air intakes etc., but the engine's design would not have been a problem. There were plenty of steam engine classes running with different kinds of fuel without any influence of power output. On the other side - because this still won't die - if Big Boy would have used better fuel it just won't have put out more steam or hp, but would have used less fuel, nothing more.

[dredmann]

The figures for drawbar tractive effort on the Y6b appear to be in compound operation, and before the final round of upgrades, so they may be somewhat below what a Y6b might have ultimately achieved. I am not sure what would be the maximum speeds capable of using completely simple operation, but above that you had the option to use something more than just the once-expanded steam from the rear cylinders in the front cylinders. No doubt the Y5/Y6 classes were complex beasts, optimum operation of which required more than the usual degree of knowing what you were doing.

So we gonna get N&W 2156 and UP 4017 restored, and have a competition?

[BigJim]

I think on a performance level, they could do any job, but few engines could do the job of BB..... And could haul 3250t@1.55% at 15-20mph

Over the Blue Ridge grade, which would be very similar, the Y6 was rated at 4600 tons in slow freight and 4100 tons in time freight service.

50 -55 mph speeds on a Y6 were not uncommon. As a steam engineer related to me, 63 mph was about as fast as you wanted to run a Y6. After that things started to get a little shaky. So the problem a Y6 would have would have in keeping up with a Big Boy would be more from the inherent dynamic forces and speeds in the running gear brought on by the smaller drivers.

As for running out of steam, with good coal, N&W's big three had no problem with steam production. Engineers have also told me that even in simple, the Y6 had no problem keeping a full gauge of steam and could even lift the pops.

Too bad Road & Track magazine didn't do performance tests (like they did with the Strasburg Decapod one April) on steam locos when they ruled the rails.

 

[CSSHEGEWISCH]

It has to be remembered that any steam locomotive's performance, even that of an ancient saturated steam 2-8-0 working a light-rail granger branch, is highly dependent on the skills of both the engineer and fireman.  Robert Le Massena alluded to this in his article "The Big Engines", with a comment about the many factors that could affect performance, including "what the engineer had for lunch".  From what I've read, the T1 and Q2 had incredible potential but not enough crews took the effort to get the best performance out of them.

[feltonhill]

This is moderately OT, but it supports Lars statement regarding PRR T1 handling problems and provides a documented example of variable skills of enginemen.  Here's a quote from a PRR internal memo dated 9/29/45 (from Hagley Library).  I thought it would make interesting reading:

"After we had taken sand at Conemaugh the engineman had the train moving and if he had left the throttle in its position, the locomotive would have hauled the train away, but he jerked it open, the locomotive slipped, the train stalled and we had to put a pusher on to get the train away."

This quote was take from a report by Asst. ME Decker who was riding the locomotive during an extensive over-the-road test period where 6110 and 6111 were being used on regularly scheduled trains.

Previous paragraphs in the same memo describe this engineman's insistence on using a heavy throttle during poor rail conditions east of Pittsburgh, where he allowed the locomotive to slip so badly that Decker stated:

"...I was afraid we would do some damage to the locomotive before the engineman noticed the slip and closed the throttle."

On the other hand, given one of the best crews, things were different. Just three days before the above run, #6110 took a 21-car passenger train over the Middle Division, rain and fog the whole way, with two slips recorded between Harrisburg and Altoona. They left Harrisburg six minutes late and arrived two minutes early at Altoona. There were at least three intermediate stops and no difficulties were encountered at any of them. This run is described in PRR memo dated 9/24/45. It is based on a report by a Special Duty Engineman who was riding 6110 during the run.

The above contrasting operations were recorded during a two month test period during Sept and Oct 1945. Most or all of the reports of runs during this period have survived. How the crews operated the T1's had a major impact on their performance. 

[Anonymous]

Quote: 

"It is not the ability of coal to burn "More or less" powerful but the overall design of the boiler to feed the cylinders."

I meant it in a way of efficienty, that certain firebox design's are nesseccary for certain kinds of coal and can improve overall efficiency dramatically. "The firebox was one of the not good designed parts of BB", to literally repeat Kratville about what he write in his book. Built as a compromise, but could deliver enough power if you get used to it. However, ' never saw any of the Western Roads ever used those deep "Super Power" boxes. Burning Oil was another alternative for them, also. 

"...4-4-4-4 Duplex from the PRR. Engineers swore they were slippery"

Because the engineers did not know how to handle this new kind of machine.

"Take the Triplex..."

On hot summer, the cap of a Triplex was the coolest place ;-)

 

Regards

lars

 

[Anonymous]

It is not the ability of coal to burn "More or less" powerful but the overall design of the boiler to feed the cylinders.

Take the Triplex. Impressive eh? But it pants and runs out of steam anywhere above 30.

You are simply heating a huge amount of water to boiling and then beyond. That is all there is to it. Dont overthink or hurt yourself trying to determine if one is better than another.

All engines will max out somewhere at max hp and will not give you any more no matter what you pour into it.

Now having said that, I expect folks to jump on here and show me a 350 cat buffed with 4 turbos, pressuriezed fuel systems and extreme output capable of taking 50 ton up a 7% grade at 70+ mph and have horses left over to accelerate.

It may not have the fuel to make it over the top with such large amounts of fuel (Energy) being fed to it.

Also keep in mind that the Y6b was a Compound and probably operated somewhat differently than.. say a Big Boy that was taking steam in all 4 cylinders as it came from the boiler without reusing any of it.

Finally but not last, consider the 4-4-4-4 Duplex from the PRR. Engineers swore they were slippery and worthless but wispered about thier 100+ mph performance with lots of horses to spare but no room left. Fact? Legend? Myths? You tell me.

40 mph is good speed for steam. In fact, I think today's engines with thier impressive performance STILL run trains at average of 40 mph. Maybe Im wrong.

Or consider the B&O "Big Six" those were doing service doing Passenger Helper service at 30 mph or so.. UP HILL.

[Anonymous]

To Railway Man:

did not notice this thread earlier, much information there which will take some time to get through it. Thank you!

Lars 

[Railway Man]

This was discussed a month ago at http://trains.com/trccs/forums/1304887/ShowPost.aspx

Average values are:

1. Hanna Basin, 10,000 BTU/lb.
2. Rock Springs, 10,900 BTU/lb.
3. Central Appalachia, 12,500 BTU/lb.
4. Northern Appalachia, 13,500 BTU/lb.
5. Illinois Basin, 11,800 BTU/lb.

That doesn't necessarily mean that the locomotive burning 14,000 BTU/lb. coal is automatically 10% more powerful or more efficient than a "similar" locomotive burning 12,600 BTU/lb. coal or even the same locomotive burning 12,600 BTU/lb. coal.  I know absolutely nothing about steam locomotive firebox design, firing rates, or boiler efficiency.

RWM 

[Anonymous]

"Quote":

"Y6b was not meant to deliver useful work at speeds in excess of 40 mph"

And is not it just the reason, the N&W had in addition the Class A, too?

@clash: I guess the Coal from Hanna and Rock Springs (Food for the BB) is lower qualitiy and would not burn so efficient. Ok, don't have a qualified source for that, but I read once that the coal in BB's firebox would never touch the grate, 'cause burned so quickly. A deeper firebox, feeded with suitable coal, may spread and keep the heat better... However, the y6 keeped its firebox above the rear drivers, same BB. Maybe the Y6 would do better with low grade coal than an "A" ? But how much relevant is an 10% -20% difference between the heat content related to hp? 200-300hp?

lars

[Railway Man]

Erik:  Good job!

I took your table and inserted the numbers for the Y6b that I derived from the N&W graph reproduced in "Norfolk & Western Steam, the Last 25 Years," Ron Rosenberg, Quadrant Press 1973, which compares the Y6b, Class A, and steam-turbine electric.

Speed    Allegheny      Big Boy    Y6b

10MPH    105,000       128,000   121,000

20MPH    92,000         98,000      94,000

30MPH    75,000         72,000      63,000

40MPH    60,000         56,000      33,000

50MPH    48,000         40,000          N/A

The graph cuts off for the Y6b at 40 mph, for the steam-turbine at 50 mph, and the Class A at 60 mph, which would seem to indicate that the Y6b was not meant to deliver useful work at speeds in excess of 40 mph.

RWM 

[erikem]

Don't know how tonnage ratings would comapre on different profiles, but the drawbar tractive efforts (in pounds) for the Allegheny and Big Boy are as follows:

Speed    Allegheny      Big Boy

10MPH    105,000       128,000

20MPH    92,000         98,000

30MPH    75,000         72,000

40MPH    60,000         56,000

50MPH    48,000         40,000

The numbers for the Allegheny were derived from the graph on the upper left hand corner of page 204 of Huddleston & Dixon's book, while the numbers for the Big Boy were derived from the graph on page 20 of Kratville's book on the Big Boy - the graph for the Allegheny had better resolution than the graph for the Big Boy.

I would expect the Y-6b to be (ahem) running out of steam at 50MPH. 

[timz]

[N&W] Y-6 was permitted to run 50, and within this entire speed range tonnage ratings were higher than for Big Boy.

What were their tonnage ratings at 50 mph? 

[clash]

I wonder how those NW and C&O locomotives liked burning that Wyoming coal  being designed for that good eastern bituminous. All this talk of H.P. does'nt say much about how it can vary greatly depending on the quality of the coal.

[Anonymous]

"Quote"

"They could! Y-6 was permitted to run 50, and within this entire speed range tonnage ratings were higher than for Big Boy"

High tonnage was given to the y6, and they were very efficent to manage it. But I think it is not correct to justify the engines just by the tonnage they pulled. Do Speeds beyond 10mph really account? Theoretically, at speeds more than 10mph, the BB is quite similar to the y6(b?) and has advantages above 30mph. Then, pretty much between the Alley and a Class A (by comparing their tractive efforts and hp tables). The average speed for an Evanston - Green River, or Laramie - G.R. run was more than 30mph, including stops. Extras would be faster. And they run could 70mph? Why? 'Cause just could do so ;-)

UP just crossed a x-6-6-x with a x-8-8-x, concerning TE, Speed and HP, didn't they?

lars 

[Anonymous]

Quote: 

"However the Bigboy would be most difficult to use in the east for a variety of reasons"

 

Hmm, they were too long for easten turntables and their clearances?

I think on a performance level, they could do any job, but few engines could do the job of BB. At the Ogden - Wasatch - Green River - Ogden-run (more than 300miles, for 11 years ) they would be difficult to beat. And could haul 3250t@1.55% at 15-20mph

lars 

[VAPEURCHAPELON]

The Y6b moved mountains in the east but could not keep up out west on a schedule with the Bigboys running 50 mph and a mile of Produce.

They could! Y-6 was permitted to run 50, and within this entire speed range tonnage ratings were higher than for Big Boy. Impressive what a tiny percentage of running time Big Boy was used above 50mph...