I think all of you guys should buckle on your pocket protectors, whip out your slide rules and HP calculators, and face off.
First one that can devise a working real time model/example of Einstein"s theory of relativity wins a trip to Disneyland…
Oh, and the SD40 can move more train, but the GP40 can kick cars better and faster…
Ed[:D]
Ooops!
Let’s try again. I buckled on my pocket protectors, dusted off my very old slide rule (I’m not HP calculator qualified), put on my battered 45 year-old Engineer’s striped cap (an affectation from university days) and started to read Al Krug’s treatise. However, after a few minutes my brain circuits began to overheat with the effort of moving up the steep learning curve involved. And it wasn’t because of Krug’s explanations; his writing is a model of clarity, combined with a bit of humor, but obviously there’s a lot more to this topic than the casual railfan on the trackside might suppose-it’s great stuff.
I want to know what will win an good ol’ tug of war. Big Boy vs. The SD-90.
(Da da da. SUNDAY SUNDAY SOMEDAY)
Somewhat related: I wanted to know what would win a tug of war with stick vs. auto. That was found out when my buddy got the same exact bronco as mine with the 302 v8, except his was an auto and mine is a five speed. Out to a hard packed field with three big chains we went and the pull was on. In the end there were two broncos that dug themselves down to the axles without moving one way or the other.
If the big boy could out tug the sd90, how many sd90s would be needed?
Adrianspeeder
Isambard,
Wasnt really picking fun, too much.
But you pointed out what I was trying to get across…
You can figure HP, tractive effort, and run the numbers till your fingers wear out, but its all theroy…Randy was trying to get that across.
In theroy, you can come up with a infinite hp for a steam engine, but at some point, you reach the place where the metal and materials can no longer support the forces, and thing blows apart.
To answer Adrians question, neither one would win, the drawbar would fail…
Point is, there is a different application for each figure, hp is used to come up with one set of needed figures, tractive effort for another.
SD40s are great for hauling freight, lousy for flat yard switching.
GP40s switch great, but you need a few to haul a heavy freight.
It all depends on how you are going to apply the numbers, and to what purpose.
Ed[:D]
…Would you believe Ed I actually have a real slide rule still in the office here and one that was actually used …[in the past, at work]…before calcuators. It’s a nice big one too. One of our Engineers in our lab used to use a round slide rule…Ever see one of those…?
Thomas Edison had a distrust for the number crunchers, the story goes that a young math wiz was asked by Mr. Edison to find the volume of a new shape of light bulb. The wiz involved himself in days of calculations only to have Mr. Edison tell him to fill the damn thing with water and see how much it held.
The long and the short of it is you don,t always know how a machine is going to perform until you put it to work, many locomotives that looked good on paper were big disappointments, like the SD-24 with 15 steps of transition, when it worked , it was OK but a flawless transition on a SD-24 was rare.
I do know the ACTUAL performance of an SD-90mac and can tell you beyond a shadow of a doubt that the SD-90 will pull a big boy around easily, the SD90 won,t lose adhesion and slip, the big boy will spin it’s wheels. There are a number of reasons railroads converted from steam… efficiency
This is a good thread, lots of fun discussion
Randy
ptt 100
correct, by the way the GP-40 GP-40-2 are and will always be MY all time favorites
Randy
I always liked the acceleration and sustained speed ability of the Amtrak F-40, after [8D]all it’s just a dressed down GP-40 (with way too many parasitic loads)
GP-9’s lasted a long time, too, and some got a nose job!
Quinten,
no, havent seen a round slide rule, but my brother in law, who is a civil engineer, still keeps his rule in his briefcase, because “battries can fail”…and I think he just wants to keep the skill needed to use it from getting too rusty.
ptt 100, if you add a space between the d and the B in my screen name, its easier…and, in your profile, where you list “making fun of idoit foamers” as your hobby, you misspelled idiot.
By the way, if you have such a active dislike of “foamers”, why are you bothering to waste your time posting on a fan website?
Ed
I have stated that my all time favorite is the GP-40, however if I had my own little short line to run I would certainly pick a GP-9 . This is only being practical because I would be living in fear for the turbo in the GP-40, just waiting for a $ 20,000.00 part to go to hell
CSX is definitely getting a lot of mileage out of its GP40-2’s. A fair number of them have been converted into slug mothers and they turn up in the Chicago area periodically in transfer service with road slugs plugged into them. I would assume that most of the slug sets are in mine run duty.
I feel the same way about management here, also.
The best way to cause them ulcers is to do exactly what they tell you to, not what you know needs to be done.
Whats the deal with fans?
I like the idea that what we do for a living attracts peoples interest.
After all, there isnt too many fan clubs or magazines for UPS drivers!
How about, instead of picking on them, and playing the one up manship card, you teach them instead?
Trust me, there are a lot of fans that are very interesting, friendly and wanting to learn about what we do, not just “watch trains”.
You should be flattered that they want to hear about what you do.
I wi***he carriers would bring steam back too!
Not as a working tool, of course, but as a PR tool, look at how many folks flocked out to see UP’s 3985 and 844?
And UP needs all the good pr they can get right now, just saw on the news where they had a head on outside of San Antonio, unknown how many crew members dead, trashed four locomotives and busted open some chlorine tanks, bad scene.
Ed
Isambard asks about drawbar limits. John Armstrong’s THE RAILROAD, WHAT IT IS WHAT IT DOES, 1990 edition gives a clue in saying about draft system strength, “coupler knuckles for general service are made of Grade B steel and have a strength of 350,000 lb.” The knuckle is designed to be the weak point in the system, since it is the most easily repaired by the road crew. I’m not a railroader by profession, but it seems to me that it would be easy for a pair of modern diesel units to exceed that limit and yank a train apart. What do you pros say about that? Also note that Armstrong’s book was written 14 years ago and newer couplers may be stronger, but the weak link principle still stands.
With the latest questions about horse power/ tractive effort ,this thread will answer many questions and provide alot of formulea for the math inclined.
Randy
Of course a tug-o-war isn’t really a fair test because steam and diesel produce their maximum TE under different conditions. The TE of a diesel is highest in low speed <5 or so mph, while a steamer produces its highest TE in its mid-speed range.
Hence that old saying; A diesel can start more train than it can pull and a steamer can pull more train than it can start.
Hugh, your statment is really not true. Steam locomotives produce their highest TE readings at low speed also. By 20 mph, steam locomotive exhibit the same declining TE, constant HP curve as diesel-electrics.
The second part of your statement may of been true with first generation diesel-electrics, but with modern versions, the limiting factor in train movement is adhesion, not overall power as it was in the first generation diesels.
Are you talkng about this thread or the “Shells” thread? I haven’t read all of the posts in this thread yet. I have skimmed over the posts and did not notice any formulas.
http://www.trains.com/community/forum/topic.asp?page=3&TOPIC_ID=19048
[quote]
Originally posted by Randy Stahl
I’d be glad to send any one copies of the EMD charts & graphs for just about any locomotive EMD built, in fact I have one in front of me right now for an sd-45. I still don’t see any thing about tractive effort, how ever you are correct in that a wheel slip correction will affect main generator exitation , but when the HP is calibrated on a locomotive, tractive effort is not an issue, the wheel slip system is calibrated by itself. Locomotive horsepower is kilowatts Period.
It is correct to say the GP-40 has it’s motors wired in parallel, it does not make transition. The AR-10 main alternator has it’s limitations therfore with the addition of 2 more traction motors the capacity of the AR10 is exeeded, the locomotive starts in series to reduce current demands on the AR10. You are correct, the GP-40 should kick the SD’s butt, however since the kilowatt out put of the AR10 is divided over 4 motors, not 6 ,the horsepower per traction motor is greater causing wheel slip/ lower tractive effort, the GP40 will accelerate very quickly. The comparison I use when I’m holding training classes is to compare the GP and the SD to a corvette and a Jeep.
Answer this, suppose you went out to the service tracks ,to a locomotive you were entirely unfamilier with, suppose the locomotive" would not pull" , your job is to repair this engine. Where would you start? Remember you are not familier with the engine, HP , TE is all unknown , all you have is a wiring schematic.
The formula for calculating steam locomotive HP is correct, it is well known that steam loco hp is limited only by mechanical technology, had the steam locomotive continued developement we would have seen how limitless they really are, just the developement of poppet valves made a big difference in the valve efficiency. The formula does not lie. take a calculator and try it.
It is true that a diesel locomotive HP is infinite you can increase RPM, increas the fuel etc in fact EMD did jus
This is the most clealy written and concise explanation to all this tarnation yet, whew !!!