The paragon 2 Y6B has a minimum radius of 18 inches. I have one and it does negotiate that size curve.
http://www.broadway-limited.com/paragon2nandwy6b2-8-8-2.aspx
Springfield PA
Hamltnblue As far as the Op's question. What is the reason for wanting to know the length of the model? Are you considering one on the layout? If that's the case you could also consider the Y6B 2-8-8-2. It's articulated and will work on most layouts.
As far as the Op's question. What is the reason for wanting to know the length of the model? Are you considering one on the layout? If that's the case you could also consider the Y6B 2-8-8-2. It's articulated and will work on most layouts.
Yes, the original question was related to how well something larger than my 2-6-6-2 would operate on my layout. i have a couple curves that are tight as 20", The rest are a little larger. I enjoyed the discussions.
Thanks to all that answered.
Lee
J.Rob In some railroad books available there are excellent discussions regarding the merits of each design and their short-comings. One that compares the big boy to the H-8 reveals how a much larger and deeper firebox could be used on the H-8 since it did not have to be placed above the drive wheels like the big boy.
In some railroad books available there are excellent discussions regarding the merits of each design and their short-comings. One that compares the big boy to the H-8 reveals how a much larger and deeper firebox could be used on the H-8 since it did not have to be placed above the drive wheels like the big boy.
The H8 firebox was bigger than the Big Boys, but not by much. 762 sq.ft. for the H8 vs 704 sq.ft for the Big Boy. The H8 and EM1 had almost identical firebox sizes. 762 sq.ft. for the H8 vs. 758 sq.ft. for the EM1.
You are right. They didn't force the 2-10-4, but they did force an existing design. The PRR wasn't too happy with the Class A performance on mountain grades. The front drivers tended to slip a lot on hard pulls, which is why the N&W paired them with the Class Y in the mountains. The C&O 2-10-4s had better adhesion on mountain grades, but were a lot harder on the track at speed than the Class A. Given a choice, the PRR would have used neither design.
The war production board did not force the 2-10-4 down the throats of the Pennsylvania railroad. The requirement was for an existing design to be used. The Pennsy tested a C&O 2-10-4 and an N&W 2-6-6-4 and chose the non articulated design. Some railroads did not like articulated locomotives.
In the case of the C&O the next evolution of the 2-10-4 was the 2-6-6-6, or what was originally thought of as a 2-12-6. Both the 2-6-6-6 and the 2-10-4 were used on heavy passenger trains. The 2-10-4s were not continued in passenger service as the side rods were so wide that they hammered through the passenger platforms due to lack of clearance.
One thing that does not seem to be addressed very often is the versatility of some of the designs used by the C&O. They were used in the flat lands of Ohio as well as the mountains in Kentucky, West Virginia and Virginia. The superpower designs were both fast and capable of drag work when needed.
When looking at the superpower designs 2-8-4, 2-10-4 and 2-6-6-6 they were the basis for or used by other roads and were quite numerous. More than twice as many 2-6-6-6s were built as big boys. The 2-10-4s were over 150 strong 125 for the Pennsy and 30 for the C&O if memory is accurate.
ATLANTIC CENTRAL That's an interesting view. Both locos had lateral cushioning on the forward drivers. The actual difference in rigid wheelbase is 27". I find it interesting that you don't think that would matter, yet the S1a 2-10-2's could not even stay on rails on Lines West, but a T-4 had no problems. The wheelbase difference there is 36". If 36" makes the difference there, then 27" would give the EM-1 the edge in the curves compared to the Big Boy.
That's an interesting view. Both locos had lateral cushioning on the forward drivers. The actual difference in rigid wheelbase is 27". I find it interesting that you don't think that would matter, yet the S1a 2-10-2's could not even stay on rails on Lines West, but a T-4 had no problems. The wheelbase difference there is 36". If 36" makes the difference there, then 27" would give the EM-1 the edge in the curves compared to the Big Boy.
I did not say it never mattered. I said it didn't matter on the B&O's high speed main lines where the EM1 ran at top speed. On the Pittsburgh Line, the B&O even ran the 2-10-2 S1a at over 70 mph. If the track can take a 10 coupled loco running 70 mph+, it would be no problem for the articulated Big Boy to do the same.
ATLANTIC CENTRAL And the B&O only flirted with the idea of a Northern, never owning or building any?
And the B&O only flirted with the idea of a Northern, never owning or building any?
Why would they bother wasting their money? For heavy fast freight, the S1a did the job in its territory just as well as any 4-8-4 could, if not better. Then there was the EM1, which would blow any 4-8-4 ever made into the weeds on a fast freight assignment.
When a SuperPower 4-8-4 actually did run on the B&O main lines, there was no issues at all. The C&O 614 had no trouble running at passenger speeds (79mph) on these lines. Neither did the 2101. I was on many of them in an official capacity, so I would know. In the steam era, the B&O P7, and T Class worked just fine in passenger service. The rigid wheelbase of a 4-8-4 was not the reason why the B&O didn't buy any. They simply didn't need them.
ATLANTIC CENTRAL Why did the C&O never build any more 2-10-4's after their 1930 purchase? But instead bought 2-8-4's and H-8's?
Why did the C&O never build any more 2-10-4's after their 1930 purchase? But instead bought 2-8-4's and H-8's?
Maybe because articulated locomotive engineering evolved, and they were an outdated design. The PRR would have never went with the J 2-10-4, which was a carbon copy of the 1930 C&O design, as late as they did if the War Production Board didn't force it down their throats.
GP40-2 ATLANTIC CENTRAL: ...The Big Boy with its larger drivers (68") has a rigid wheelbase of 18' - 9" compared to the EM-1 which had smaller drivers (64") and only had a rigid wheel base on each set of drivers of 16' - 6". ...Yes the EM-1's where well balanced and fast enough for 80 mph. But that would have been about their top speed. Remember they are only hitting those speeds on the long straights, not as they are winding through the mountains. At 80 mph a Big Boy is just starting to "stretch its legs", but would have had to slow down in the curves more than the EM-1. Sheldon Sorry, as a Mechanical Engineer who has worked for 3 decades in this industry, I got to disagree with those statements. First, The EM1 and Big Boy were indeed very similar engines with the exception of the Big Boy having a 4 wheel leading truck while the EM1 used a lateral cushioned 2 wheel truck for stability. While the Boy Boy operated at a higher pressure (The B&O specified a lower pressure on the EM1 to ensure a very high starting adhesion), the EM1 had a larger direct heating surface than the Big Boy, and its large Type E Superheaters raised the operating steam temperature to nearly 800 F. Based on its larger direct heating surface and higher steam temperature, I'd actually give the EM1 the horsepower advantage at higher speeds over the Big Boy. Second, when you look at the curvature of the B&O main lines, the difference in wheel base is not important. You are only talking about 24" between the two. Speed restrictions on curves would be very similar for both engines. Third, 80 mph was not "only stretching" the Big Boys legs. It wasn't good for much more based on its machinery speeds. Both the Big Boy and EM1 were good for 80 mph "every day" running, but pushing either one of these big engines to 85-90 mph on a routine basis would be asking for some potential damage.
ATLANTIC CENTRAL: ...The Big Boy with its larger drivers (68") has a rigid wheelbase of 18' - 9" compared to the EM-1 which had smaller drivers (64") and only had a rigid wheel base on each set of drivers of 16' - 6". ...Yes the EM-1's where well balanced and fast enough for 80 mph. But that would have been about their top speed. Remember they are only hitting those speeds on the long straights, not as they are winding through the mountains. At 80 mph a Big Boy is just starting to "stretch its legs", but would have had to slow down in the curves more than the EM-1. Sheldon
...The Big Boy with its larger drivers (68") has a rigid wheelbase of 18' - 9" compared to the EM-1 which had smaller drivers (64") and only had a rigid wheel base on each set of drivers of 16' - 6".
...Yes the EM-1's where well balanced and fast enough for 80 mph. But that would have been about their top speed. Remember they are only hitting those speeds on the long straights, not as they are winding through the mountains.
At 80 mph a Big Boy is just starting to "stretch its legs", but would have had to slow down in the curves more than the EM-1.
Sheldon
Sorry, as a Mechanical Engineer who has worked for 3 decades in this industry, I got to disagree with those statements.
First, The EM1 and Big Boy were indeed very similar engines with the exception of the Big Boy having a 4 wheel leading truck while the EM1 used a lateral cushioned 2 wheel truck for stability. While the Boy Boy operated at a higher pressure (The B&O specified a lower pressure on the EM1 to ensure a very high starting adhesion), the EM1 had a larger direct heating surface than the Big Boy, and its large Type E Superheaters raised the operating steam temperature to nearly 800 F. Based on its larger direct heating surface and higher steam temperature, I'd actually give the EM1 the horsepower advantage at higher speeds over the Big Boy.
Second, when you look at the curvature of the B&O main lines, the difference in wheel base is not important. You are only talking about 24" between the two. Speed restrictions on curves would be very similar for both engines.
Third, 80 mph was not "only stretching" the Big Boys legs. It wasn't good for much more based on its machinery speeds. Both the Big Boy and EM1 were good for 80 mph "every day" running, but pushing either one of these big engines to 85-90 mph on a routine basis would be asking for some potential damage.
If, as you suggest, rigid wheelbase was not a controlling factor in east coast designs, why did virtually every east coast road stay with smaller drivers or under 20' wheel bases after their first experiments with long wheelbases in the 1920's? Virtually all the eastern super power locos have wheelbases less than the 18' - 19' range?
Why was the C&O H8 built with 6 axles and high axle loads if not to keep the rigid wheel base shorter?Same with the N&W Class A?
Why did the C&O never build any more 2-10-4's after their 1930 purchase? But instead bought 2-8-4's and H-8's? Fact is the 2-10-4's wore their drivers very unevenly, which caused them to ride rough and tear up the track - a factor directly related to their long wheel base.
Yet out west bigger drivers and longer wheel bases were all the rage, FEF's, GS4's, and on and on.
ATLANTIC CENTRAL ...The Big Boy with its larger drivers (68") has a rigid wheelbase of 18' - 9" compared to the EM-1 which had smaller drivers (64") and only had a rigid wheel base on each set of drivers of 16' - 6". ...Yes the EM-1's where well balanced and fast enough for 80 mph. But that would have been about their top speed. Remember they are only hitting those speeds on the long straights, not as they are winding through the mountains. At 80 mph a Big Boy is just starting to "stretch its legs", but would have had to slow down in the curves more than the EM-1. Sheldon
A few more thoughts that should be noted:
The nature of the way an articulated loco is hinged, makes the effect of its rigid wheelbase a little different than a non articulated loco like for example a Mountain class loco. The front Engine does put a side load on the rear engine as the loco goes through a curve.
Without the front set of drivers hinged out in front of it, a loco like a B&O T-3 does pretty well on curves even with its rigid wheelbase of 18' - 3". But even at that, the EM-1 had the advantage in the application you mentioned because it could likely keep better speed over the whole route compared to a pair of Mountians or a BIg Boy.
And, if you study the development of 4-8-2's on the B&O you will see they went backwards in driver size and wheel base from 76" drivers and 19'+ wheel bases on the early ones, to 70" drivers and 18' - 3" wheelbases for the T-3, the only Mountains they had in quantity. I don't know about the T-3 in particular, but many Mountain class locos also had lateral motion devices on the front driver, allowing them more side to side motion in curves.
In general many east coast lines experimented with longer wheel base locos in the twenties and early thirties but then moved back to shorter wheel bases for their last steam purchases. The C&O bought their 2-8-4's AFTER buying 2-10-4's, the Virginian's last steam where 2-8-4's and 2-6-6-6's. The B&O EM-1's came in 1944, way after the S1a, last built in 1926.
In the twnties it was the quest for tonnage - by the forties they wanted speed and power - on the trackage they had in place. The only way to get speed on thecurves in place was to make the locos more nimble while still making them bigger and super powered.
GP40-2 ATLANTIC CENTRAL: A Big Boy would have been useless in the Appalachians, it would have had to go so slow around too amny curves that it would never keep the schedule. Sheldon So how was it that the B&O routinely used their 2-8-8-4 EM1 on 80 mph express mail trains through the mountains in PA and WVa? The EM1 was only 18 inches shorter than the Big Boy (engine vs. engine --the Big Boy's tender was a few feet longer than the EM1's tender). The EM1 produced so much power at speed that the B&O was able to eliminate the pair of 4-8-2 Mountain class locomotives that was needed to handle the express mail trains. Seems to me that the similar Big Boy would fit right in to this type of service in the East.
ATLANTIC CENTRAL: A Big Boy would have been useless in the Appalachians, it would have had to go so slow around too amny curves that it would never keep the schedule. Sheldon
A Big Boy would have been useless in the Appalachians, it would have had to go so slow around too amny curves that it would never keep the schedule.
So how was it that the B&O routinely used their 2-8-8-4 EM1 on 80 mph express mail trains through the mountains in PA and WVa? The EM1 was only 18 inches shorter than the Big Boy (engine vs. engine --the Big Boy's tender was a few feet longer than the EM1's tender).
The EM1 produced so much power at speed that the B&O was able to eliminate the pair of 4-8-2 Mountain class locomotives that was needed to handle the express mail trains. Seems to me that the similar Big Boy would fit right in to this type of service in the East.
It has nothing to do with overall length, it has every thing to do with the rigid wheelbase of each set of drivers. In that regard a Big Boy and the EM-1 are not very similar.
The Big Boy with its larger drivers (68") has a rigid wheelbase of 18' - 9" compared to the EM-1 which had smaller drivers (64") and only had a rigid wheel base on each set of drivers of 16' - 6".
Relative to drive size alone, comparing a BIg Boy to an EM-1 is like comparing a the average Mountain class to the average Mikado class.
This made the EM-1 more nimble and not as hard on trackage with lots of curves.
Yes the EM-1's where well balanced and fast enough for 80 mph. But that would have been about their top speed. Remember they are only hitting those speeds on the long straights, not as they are winding through the mountains.
A curve on which the B&O would have restricted an EM-1 to lets say 45 mph would have slowed a Big Boy to 30 or less because of its larger drivers and longer rigid wheel base of each drive set.
ALSO, as a group, articulated locos have an advantage over non artulated locos when it comes to loss of traction in curves. This same theory applies when comparing articulated locos of different wheel bases. Shorter wheel bases are better on curves - the B&O lines west has lots of curves.
The open country where BIg Boys ran has lots of straight and flat, occasionally interruped by some really tough mountain curves and grades. Out west, making good time on the prarie was more important that maintaining medium speeds through the mountains. That's why many western locos have larger drivers than east cost locos.
The modern east coast locos built with larger drivers used less axles and higher alxe weights - like I explained earlier - like the N&W Class A and C&O H8, too keep rigid wheel bases short. Even the N&W J has smaller drivers than west coast Northerns designed and built at the same time - same reasons.
To give an example in reverse, the N&W Y3's sold to the ATSF during WWII were failures out west. They tried to run them too fast in open country and kept cracking frames - yet at medium east cost speeds they were great locos and the basis for the Y6.
These design differences may seem small to you, but they make a big difference. Steam locos, articulated or otherwise, are greatly effected by rigid wheel bases vs desired speed/sharpest curve relationships.
Some east coast roads used long rigid wheelbase locos - best example, the PRR, rather than articulated locos - unlike most east coast roads, they had a easy crossing of the mountains, and VERY heaviily built trackage, and gentle curves almost everywhere.
Using the B&O S1a as another example. These long rigid wheel base 2-10-2's where used on the line to Pittsburgh, Sand Patch Grade, A long steady grade with easy curves, like much of the PRR. Those locos performed great there.
On one of the few times the B&O tried to use the S1a on the line to Cincinnati, with its much sharper curves, they layed the loco on its side! Several other attemps caused derailments.The curves where too sharp for its very long 22' - 4" rigid wheel base! Yet the EM-1's with only a 16' - 6" wheel base on each driver set sailed through there at moderate speeds all time.
ATLANTIC CENTRAL A Big Boy would have been useless in the Appalachians, it would have had to go so slow around too amny curves that it would never keep the schedule. Sheldon
For whatever reason the Seaboard 2-6-6-4s were incredibly racy and fast looking, particularly in the original builder's photos. Those 69" drivers look bigger than that in the pictures. The photo here does not quite do it justice -- they cluttered it up in later years. Originally it was a very smooth and clean looking boiler.
http://ctr.trains.com/en/Railroad%20Reference/Steam%20Locomotives/2006/06/Steam%20locomotive%20profile%202-6-6-4.aspx
Dave Nelson
BerkshireSteam ATLANTIC CENTRAL: to follow up this balance topic with a little, one of the worst locos in that regard was the USRA Light 2-10-2. Its small drivers and long heavy side rods made it hard on its own frame and the track at speeds much over 20 mph. In the end, they where considered only useful as "transfer locos" - in other words over grown switchers. Sheldon How would that compare to a 0-10-2? Could the 2-6-6-2 be converted to a 2-6-6-4? How about a -6-4? I know I know I'm making up my own concoctions again.
ATLANTIC CENTRAL: to follow up this balance topic with a little, one of the worst locos in that regard was the USRA Light 2-10-2. Its small drivers and long heavy side rods made it hard on its own frame and the track at speeds much over 20 mph. In the end, they where considered only useful as "transfer locos" - in other words over grown switchers. Sheldon
to follow up this balance topic with a little, one of the worst locos in that regard was the USRA Light 2-10-2. Its small drivers and long heavy side rods made it hard on its own frame and the track at speeds much over 20 mph. In the end, they where considered only useful as "transfer locos" - in other words over grown switchers.
Well, the few 0-10-2's that existed where just that as well - giant switchers.
As for making a 2-6-6-4 out of a 2-6-6-2, that would not be practical. The reason for the 4 wheel trailing truck is to support a larger firebox - the firebox of the 2-6-6-2 simply does not justify a 4 wheel truck.
Railroads did change the wheel arrangements of locos from time to time. One good example was when the B&O converted 2-8-0's into 0-8-0's.
By removing the lead truck, this put more weight on the drivers making them better as switchers but limited speed.
Different railroads have/had different wieghts of rail and grades of roadbed, so they have different requirements for loco axle loading. Some locos had more lead/trailing wheels just to keep alxe loading within limits. Eample - the classic NKP Berkshire has lower axle loading than several of the largest Mikados built.
And some of those large Mikes where actually more powerful than the Berkshire. To simulate my own heavy Mikes I have converted Bachmann Berkshires to Mikes.
This is a loco that could have been built, but would have required heavy trackage like that on the C&O or PRR and would have actually had more TE than a NKP Berkshire.
ATLANTIC CENTRAL to follow up this balance topic with a little, one of the worst locos in that regard was the USRA Light 2-10-2. Its small drivers and long heavy side rods made it hard on its own frame and the track at speeds much over 20 mph. In the end, they where considered only useful as "transfer locos" - in other words over grown switchers. Sheldon
wjstix I don't have the exact numbers, but a 2-6-6-4 and 4-6-6-4 would be pretty close to the same size. They both had fairly large drivers so they could run at mainline speed. The USRA 2-6-6-2 is smaller...actually the boiler isn't much longer than a USRA 2-10-2 I believe. The 2-6-6-2 had much smaller drivers and had a max speed of around 20 MPH - or at least it could only go that fast before it started damaging the track. (Because of the small drivers, it was difficult to counter-balance the weight of the siderods, so above 20 MPH they would "pound" the track pretty hard from what I've read. A Challenger with something like 70" drivers could go much much faster.)
I don't have the exact numbers, but a 2-6-6-4 and 4-6-6-4 would be pretty close to the same size. They both had fairly large drivers so they could run at mainline speed. The USRA 2-6-6-2 is smaller...actually the boiler isn't much longer than a USRA 2-10-2 I believe. The 2-6-6-2 had much smaller drivers and had a max speed of around 20 MPH - or at least it could only go that fast before it started damaging the track. (Because of the small drivers, it was difficult to counter-balance the weight of the siderods, so above 20 MPH they would "pound" the track pretty hard from what I've read. A Challenger with something like 70" drivers could go much much faster.)
To follow up this balance topic a little, one of the worst locos in that regard was the USRA Light 2-10-2. Its small drivers and long heavy side rods made it hard on its own frame and the track at speeds much over 20 mph. In the end, they where considered only useful as "transfer locos" - in other words over grown switchers.
Lee, as others have explained Challengers and the N&W Class A, are big modern steam locos, much bigger than the USRA 2-6-6-2. Also the UP Challenger and Class A are "simple" locos, meaning they use high presure steam on all cylinders, the 2-6-6-2 is a compound, using the steam first in the rear cylinders than in the front cylinders.
The 2-6-6-2 wasa medium sized road engine, very popular on the winding curves and steep grades of the C&O.
Stix is correct in that the 2-6-6-2's are "drag freight" locos, but they could and did go a lot faster than 20 mph. Loco driveline balancing relates to more than just driver size, it also relates to number of axles, which increases connecting rod weight, which requires more counter weight on each wheel.
So a 2-6-2 with 56" drivers would be easier to balance than a 2-10-2 with 56" drivers. Keeping that in mind, the 2-6-6-2 is like two seperate 3 axle locos when it comes to balancing.
Actually, a USRA or similar 2-6-6-2 as used on the C&O (the Bachmann model you have) could and would have easily reached 40 mph or more with no problem and no track damage. The limiting factor would have been boiler capacity to maintain speeds over 40 mph for any amount of time.
Speeds in the 30-35 mph range with 2000 tons in tow would have been typical in day to day operations. Think of the 2-6-6-2 as a 4-8-2 or 2-10-2 that is better suited for grades and curves, but is about the same as them power wise.
A Challenger on the other hand is a modern high speed, high power dual purpose loco - the articulated step up from a big 4-8-4. The N&W Class A (2-6-6-4) and the C&O H8 (2-6-6-6) are similar in that regard - large drivers, very powerful and very fast. The H8 in fact actually makes more boiler HP than a Big Boy.
People not familar with Appalachian mountain railroading often miss and important point compaired to Rocky Mountain railroading. In the east, the distances are shorter, but there is no "prairie" on which to make up time. From one side to the other and out into the piedmont of the east coast, the curves and grades never quit.
70 mph freight locos are useless - BUT locos that can maintain 35-45, even on curves and grades, are needed to make reasonable time. A Big Boy would have been useless in the Appalachians, it would have had to go so slow around too amny curves that it would never keep the schedule.
BUT, the 2-6-6-6 H8, with simalar power on a much shorter and more flexible wheelbase, could sustain moderate speeds with heavy coal drags through the mountains. This is why most east coast "modern steam" either had smaller drivers ( like the 70" drivers on an N&W J) or fewer axles like the H8 or the class A.
OK, likely more info than you wanted, but there you go - the 2-6-6-2 and a Challenger are worlds apart.
Keep this in mind, as Andy explained, it's not just about wheel arrangement, era of design/construction and intended use all play a role in how "big" a steam loco is.
A great example is to compare a "Russian" 2-10-0 to PRR 2-10-0, no two locos with the same wheel arrangement could be farther from being the same size.
The typical Challenger is about 2" longer than the USRA 2-6-6-2. That's without tender. And in HO. Tenders also "tend" to be longer, by an inch, maybe inch and a half.
Ed
Hello Lee,
"Stix" is correct that both the N&W class A 2-6-6-4 and the UP class 4-6-6-4 Challenger are about the same size. The UP engine is about 27 tons heavier, and both are larger than the USRA 2-6-6-2. But all Challengers and all 2-6-6-4s weren't equivalent.
The D&RGW and WM had Baldwin Challengers that were different from the UP's Alco-built engines, and the NP's Alco Challengers weren't the same as the UP's.
Likewise, the Seaboard Air Line and the Pittsburgh & West Virginia both had 2-6-6-4s that were smaller and lighter than the N&W's. The current edition of Classic Trains magazine, Summer 2011, has a good article about the P&WV engines that compares all three designs that used the 2-6-6-4 wheel arrangement.
So long,
Andy
Andy Sperandeo MODEL RAILROADER Magazine
I have the Spectrum 2-6-6-2 and was wondering how the 2-6-6-4 and the challenger compare? Are the 2-6-6-4 and the 4-6-6-4 challenger the same size?Model train size.
Thanks