Hello,
can somebody provide me with a Tractive Effort and Horsepower vs. Speed table for “Big Al”?
Any other big steamers are welcome!
Lets say for speeds
0-10, 10-20, … up to 70mph?
Thanx in advance!
Lars
Lars,
Check your PM’s. I have some of the info you want.
this site has some good info on various classes and survivors
So-called horsepower figures on the referenced site (and many others) are always suspect if they don’t have consistent adjectives in front of the noun “horsepower.” The Q2 figure of 7,900+ is indicated horsepower, measured on the Altoona test plant at a relatively high evaporative and firing rate. The Allegheny figure of 7,489 is drawbar hp and was measured during over the road tests at a more normal firing rate, but under possible favorable grade conditions. Therefore, the two “horsepower” figures aren’t comparable. Indicated HP is measured in the cylinders; drawbar HP is measured at the rear of the tender unless it’s PRR. Then it may be at the rear of the locomotive. Big differences. So unless you know what type of HP is being discussed, and under what conditions the HP figures were generated, you can’t compare the numbers. Admittedly it’s not much fun, but this is the reality of trying to compare steam locomotive performance figures. Detailed test data for the Q2, Allegheny, Niagara, N&W Class J, PRR T1, and many other locomotives exist in various archives, but those who try to use them in discussions are frequently considered didactic fuss-budgets. Steam locomotives are dynamic creations, and their performance is audible, visible and measureable, but their secrets are still not easily discovered. We just have to keep trying to understand them as carefully as possible.
The Y6b is king of the eastern hills. The TE of that engine will move earth backwards in it’s orbit if permitted to do so.
The Alley was wasted on the ups, downs and sideways. Hardly it has room to get up and run.
The western folks always had to go up hill or downgrade. They dont know any better. (Just teasing. lay off will ya?! LOL)
Got the info, thank you so much!
Lars
Quote:
“The western folks always had to go up hill or downgrade. They dont know any better. (Just teasing. lay off will ya?! LOL)”
No way, they knew better! But design concepts for the east, may not work as good for the west (and vice versa).
lars
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.
However the Bigboy would be most difficult to use in the east for a variety of reasons.
Horsepower = work availible in a unit of time. If there is additional horsepower availible near the top end then you can use it. If you used all of your horsepower to get to the top end and have nothing left over… well that all you got.
I am not exactly a horsepower man but more of a torque man. Once long ago my 300+ horse engine 3700 pound bomb of a car was defeated by a big block buick 4 door 6000 pound convertable off the light. If I had about a mile I could show him horses but doubt it. Not in that particular situation anyhow.
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…
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
“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
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.
What were their tonnage ratings at 50 mph?
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.
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
“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
This was discussed a month ago at http://trains.com/TRC/CS/forums/1304887/ShowPost.aspx
Average values are:
- Hanna Basin, 10,000 BTU/lb.
- Rock Springs, 10,900 BTU/lb.
- Central Appalachia, 12,500 BTU/lb.
- Northern Appalachia, 13,500 BTU/lb.
- 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
To Railway Man:
did not notice this thread earlier, much information there which will take some time to get through it. Thank you!
Lars
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.
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