just a thought :
Hi , all
Hi, Juniatha. I am unsure of your intent for the question’s answer as you frame it, but apart from the match between the J1 and the UP Challengers, the nod generally goes to the other versions of the Challengers in terms of their overall speed with trailing tonnages. Their weight was more lightly distributed on the rails if I have it figured out correctly, so they were easier on the rails, and we all know they could use curvatures with shorter radius than could the all-flanged rigid 10-coupled Texas types. However, when we compare the work that any one pairing could do, there really isn’t much difference between them when the mighty Bessemer & Lake Erie and the Santa Fe versions’ tractive efforts at start and at speed are taken into account.
Crandell
Crandell
I certainly agree with your information and would like to add some addtional thoughts.
The higher speed capability is certainly the main factor with the Challengers replacing the UP 4-12-2’s, but maintenance was also a factor. The third cylinder with the associated valve gear was always a high maintenance type of design. By the time the first Challengers were built, the 9000 class had run for ten years and were already being rebuilt with disc main drivers and other upgrades to allow higher speeds for the Overland main line. One more factor was the long wheelbase and the problems of using them in certain areas with tight radius cuves. They ended up on the main line and the KP line, which could handle large steam.
Did the Challengers provide a 100% substitute, I would say no since the 4-12-2’s were used until they were no longer needed. I am sure others might have different opinions but the Union Pacific continued to use them until very late in steam operations. The 9000 class were used on the Union Pa
I think CAZephyr pretty much said it all about the UP’s 9000’s, except for one thing: That loooong wheelbase was just so cool looking! Twelve drivers! Wow! No half-measures as far as UP was concerned!
But that long fixed wheel base of 6 driving axles limited where they could be operated.
Hi Crandell
My question really focuses on actual tonnage limit ratings for daily service on a given ramp section – you name it .
If we put aside all those extreme opinions offered in various articles in the past about alleged slipping problems with T-1 Duplex it was generally agreed that they were to a certain degree more sensitive at starting because of 2 x 4 coupled wheels drive sets instead of 1 x 8 . Now , my question is if that wasn’t likewise true with 2 x 6 instead of 1 x 12 coupled wheels ?
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Thank-you for your clarification, Juniatha. I believe I understand better what you mean. I guess I would want to know the numbers. What weight would each driver bear in each case, and what horsepower would each driver take prior to slipping at a given speed with a standardized weight comparison. I am out of my depth, naturally, but how do the factors of adhesion compare across drivers between the 9000 and the 3900’s? What tractive effort can each locomotive apply to the drawbar at 0.01, 1, 4, 8, 15, 20, 30, and 45 mph on a measured length of track in the districts where they shared work?
If time is a factor, which of the two needed more frequent stops for replenishment after the typical tonnages each was meant to trail at the same speed had been moved 200 miles?
Crandell
Hi,
you asked:
“Was the UP Challenger a 100 % substitute for the UP 9000 class as concerns t.e.??”
This table may not answer all concerns about TE, however it shows, that basically 4-12-2’s and 1936 built CSA 4-6-6-4 Challengers had similar tonnage ratings.
Heavy Challengers built after 1942 had some 100 tons higher ratings, reflecting their higher HP and better downhill capabilities. Example: Buford to Cheyenne is -1,55% grade, they could drift downhill with 1000tons (5100 vs 4100) more than the the 4-12-2.
So, the answer should be yes -edit- err no -equivalent -you name it
Tonnage ratings on the UP were usually only as high as a engine can start its trains on grades safetly from a full stop without stalling again.
Altough tonnage ratings were pretty similar between different classes, they certainly did achieve different road-speeds with their loads.
A wild guess of mine is, T1 and Santa-Fe Texas-Types and Q2-Duplexes would be rated quite similar like “Heavy Challengers”.
These questions have been around for a long time and there really isn’t a straight forward answer because of the wide range of pulling power and speed a locomotive goes through from start to finish.
A locomotives pulling power generally depends on the size of the wheels it is built with. The smaller the wheels the more tractive effort it can produce when starting a train. But a locomotive with smaller wheels it loses power by leaps and bounds as it moves faster. Locomotives with larger wheels on the other hand have a much harder time getting a train moving but can move a freight train at faster speeds with no problem at all. Doyle once told me starting his 4-8-4 SP 4449 was like “putting your car in 5th gear when you want to get moving”.
Another big factor is the weight on the drivers. Both the Challengers and 9000’s had a big advantage of having many wheels with a lot of weight on them. Both were excellent designs. Had we put much smaller wheels on the Challengers and the 9000’s I am sure we would see record tractive effort being produced (much like the Virginian 2-8-8-8-2) which has very small wheels.
I am sure if we put two trains next to each other,both with equal lengths and tonnage and we put a 9000 on the front of one train and a Challenger on the other they would probably end up pulling about the same speed up until about 15 mph or so. I would say the 9000 would end up leaving the Challenger in the dust from that point on until it started hitting a grade. Then the Challenger would probably pass the 9000 and climb the grade way ahead of the 9000 due to it’s much more heavier weight which would cause less wheel slip.
People often ask if todays diesels can out pull those Challengers and Big boys. I still say no way. Yes they have tractive effort way past anything the Big boys and Challengers can ever muster up. But all that horsepower and tractive effort is useless if you don’t have the weight to keep the wheels from slipping. Show me a single diesel pulling a mile long tr
Hi Thomas,
People often ask if todays diesels can out pull those Challengers and Big boys. I still say no way.
But the correct answer is yes.
Show me a single diesel pulling a mile long train up a 2% grade at 20mph like the steam locomotives did
Depending on how you define a 1 miile long freight-train, show me a steamer that can do that….
I don’t want to get too far off the original topic here but we can forget the length and just talk about tonnage. Because tonnage is the same back then as it is now. The 2-6-6-6 Allegheny regularly took 10,000 ton coal trains over the mountains on a daily basis at 20mph using just a single engine. I would have to dig up by book on the Alleghenies but I remember a single locomotive took a 13,000 tons over the hill exceeding 15 mph several times.
The Norfolk and Western class A 2-6-6-4 locomotives were rated at 13,000 tons and could take 10,000 ton coal trains over the mountains with a single locomotive.
The big boys could handle a 10,000 ton up a 1% grade.
I don’t know if you ever have worked for any railroad,let alone a class one railroad where you are taking 10,000 ton coal trains over a grade but I certainly have. I was also working for Union pacific when they were using the AC 6000 on our trains rated at 6000 hp and considered to be one of the most powerful locomotives in North america.
I can tell you with 100% certainty you are absolutely dreaming if you believe you can take a 10,000 ton coal train up a grade with a single locomotive. It would probably be coming close to stall speed if you used three locomotives no matter how new they are.
A diesel locomotive can have all the wheel slip technology in the world and all the tractive effort in the world. That still won’t change the fact that we are talking a maximum weight of around 230 tons with the majority of them are sitting around 205 tons. They simply can not pull such a heavy load with out slipping the wheels. Even with the most advanced wheel slip technology trying to pull a 10,000 ton train up a grade( I would say pulling a 5,000 ton train up a grade with a single locomotive probably wouldn’t work) the locomotive wheels are going to slip or not move at all (because of the constant reduction of the anti slip computer).
Steam locomotives like the Big boys and the Alleghenies weighed around 325 tons with o
That may be true but you can plug two or three diesel-electrics together, controlled through MU or DP under ONE throttle, and match the pulling power of that steam locomotive, be it a Challenger, Allegheny or Big Boy.
The big boys could handle a 10,000 ton up a 1% grade
Thomas,
no offense meaning, but this is absolutely, certainly not true. They were rated 4800tons at 1% at unknown speed. At a 1,14% grade, 4000 tons, 15mph were attempted.
GE AC6000 is rated 5000 trailing tons at this grade and speed.
True, a couple of Big Boys could. But a Big Boy couldn’t, unless it was geared to the rail (among other modifications).
We believe in gravity, and we believe we can calculate the force needed to overcome it with 10,000 tons on a 1% grade: 200,000 lb. We don’t know exactly how much we have to add for rolling resistance, but we’re guessing it’s more than zero.
( This is a simplified version of my posting - I don’t get the pictures to appear )
Hi Crandell <
Hello Thomas 9011,
Please let me correct a little bit your dreams of what those steamers were able to output at the drawbar. Max drawbar pull just depends on weight on drivers and their ahesion on the tracks as long as indicated pull at max pressure may be in excess of this. Neither wheel diameter nor excessive hors power or steam preasure will overcome the physics!
For example those 10 000 tons at 1 % ruling grade needed more than 220 000 pounds of tractive effort, which is almost twice of the max of which a Big Boy could deliver on a 1 % grade.
As far as I know, the 4000 had been rated at 3 600 tons on 1.1 % of Sherman Hill.This feature already needed a factor of adhesion of about 0. 20 which is regarded to be the highest to achive in everyday service for steam locomotves. Some Diesels showed up to 0.40 on trials due to their sophisticated AC-drives featuring smoth torque and slip control devices.
No shame on those fine steamers but Diesel and Electrics seem to be the better solution going uphill!
wdh
Hey Juniatha,
Interesting discussion about the actual difference in performance between both 2 and 3 cylinders and rigid frame and articulation! In Germany we once had the by far biggest no. of 3 cylinder engines class 44 decapods, almost 2 000. Thus the difference in daily performance had been evaluated: Factor of adhesion had been rated at conservative 0.185 for all 2 cylinder types while the 3 cylinder types were rated slightly higher at 0.204. There was no difference by no. or diameter of drivers. By sure indeed those 44s could do such a performance while the pacifics suffered by slipping. This may be part of the answer to the question regarding rigid frames versus smaller groups of drivers.These features were used for calculation of max loads on mainline service, as long as resulting speeds didn’t drop too much.
Those UP 9000s once had been seriously calculated to produce a max. factor o.a. 0.24 on sanded rails (Dr. Giesl Gieslingen) which haedly could had been achieved by an articulated.
I saw those links to above to sound recordings there are listed … but please enjoy!
WDH
Ok, let’s check some real data.
On the B&O’s Cranberry Grade, the 2-8-8-4 EM1s were rated at 1500 tons. An ES44AC is rated at 2900 tons on the same grade.
I’d say that blows your fantasy right out of the water.
GP40-2 we are talking about tonnage records pulled by a single locomotive. There is hundreds of steam locomotives that pulled hardly anything including the EM1 you are talking about. My point is that to this day no SINGLE diesel electric locomotive has ever pulled 10,000 or more tons over a grade.
You also don’t need to tell me that you can hook up 4 diesels and out pull a single steam locomotive. Yes I know that and I think the entire world knows that. We can also hook up 4 Alleghenies and see who pulls the most tonnage.
If you can find some statistics that shows me any SINGLE diesel electric locomotive pulling 10,000 ton trains over a grade then I will believe you. But so far all I have heard is a unconfirmed post of the AC 6000 rated at 5,000 tons. Even if this is true it is still half of what the Allegheny did and not even close to matching the steam locomotive let alone surpassing it.
Guys you need to start posting some of your links and statistics. I will admit I was wrong on the big boy data but I wasn’t wrong concerning the other locomotives.
Concerning the Allegheny pulling 10,000 tons at 15mph… http://www.steamlocomotive.com/allegheny
The Pennsylvania Q-2 4-4-6-4 had a horsepower of nearly 8,000 http://www.steamlocomotive.com/duplex/?page=prr
I’m not going to get into the Yellowstones,or the Norfolk and western locomotives because it is all coming up model railroad stuff.
That is all I am going to say on this subject so we can get back to the original topic.