Were the Norfolk & Western Y6-class 2-8-8-2’s (and other big Mallets) especially slippery, that is, given too much pulling power for their weight? Why or why not?
The reason I ask is that the old rule of thumb was that you wanted a factor of adhesion (weight on drivers divided by tractive effort) of 4. Even the Y6b’s only had about 548,500 lb on their drivers, and with an as-built tractive effort of 152,206 lb, that works out to 3.6. But wait, there’s less. They increased the tractive effort, the Drury book from Kalmbach says to 170,000 lb, the Jeffries book has a graph indicating to about 166,000; shortly thereafter, they added about 29,000 of lead to the front engine to help adhesion. At that point, about 170,000 lb and about 576,000 on the drivers means the factor of adhestion was down to about 3.4.
Lest you say that 3.4 is not that much under 4, well, consider the factors of adhestion for some other locomotives: USRA light Mikados, 4.03-4.05; UP 3986 (4-6-6-4), 4.15; N&W 1218 (2-6-6-4), 3.79; UP Big Boy 4.03; Southern Railway Ls-1 (2-8-8-2 Mallet), 4.43. Indeed, in steam locomotives I’ve considered from other railroads, none has less than 3.84, but the N&W J has 3.60. Did N&W conclude that it didn’t really need a factor of adhesion of 4?
By the way, I am not 100% clear whether the 548,500 lb on drivers figure is before or after the addition of the lead. I’m assuming it was before, because it comes from a table in the Jeffries book that lists the TE as 152,206 lb. Also, I’m assuming that the big majority but not quite all of the lead went into weight on drivers.
The only time that I ever heard anything at all about the Y6’s being slippery was right after they were modified into the “Improved” Y6-Y6a-Y6b with the new external reducing/booster valve. With the increase in power, the front engine became slippery and at that time they added the additional weight to the front frame.
dredman; 10-4 on your post. Some secrets will emerge , while others will remain hidden . The article some years back in our magazine tells of such tinkering.
switch7frg - What secrets are you referring to? If they appeared in the Nov 1991 Trains, they’re not secrets. N&W’s modifications to the Y6s were all above-board and documented in drawings and reports. The Trains article contained incorrect assumptions, errors of fact and unsupported allegations.
feltonhill; You are right about the errors and assumptions in the 11-1991 issue of trains mag. Through the years of reading trains I thought it was the truth . In seeing the engines pulling up grade from Portsmouth Ohio with a coal drag was impressive . So I knew there was changes to the A class and Y class by the rate of speed and length of the train. However, every one don’t have a copy of trains issue 11-1991 . It was not my intentionto mislead anyone.
There were no changes to the Class As except for roller bearing rods on the last group of 5. This was one of the “errors of fact” that I was referring to in the article.
The Y6’s had several revisions over the years including ballast added to the front/LP engine as noted above. All modifications were very much public information.
Increased ton-miles/train hour during the 1950s were the result of much sharper operation (e.g., use of auxiliary water tanks to eliminate intermediate stops) and the increased use of 70-ton hoppers vs the then-standard 50-ton hopper. This change in car mix permitted measurable increases in the trailing tons without a significant increase in the required drawbar pull or DBHP. N&W was a very scientific and profit-focused operator and it earned every bit of the credit that it has been handed over the years.
feltonhill; thank you very much for putting errors and truth in proper light. I finally found a photo of my favorate Y6b at Roanoke on Jul. 1950 (2179)
Big Jim ; WOW that warped my crown sheet,heh heh. ~~ As soon as I can figure out which button used to transfer chip image to avatar it will be done. Hope it will fit.
I would be very curious to read the 1991 article on the Y’s–it is available anywhere other than a library or private collection of back issues? (I’ve only been a subscriber for a couple of years.) Also, is there some published (or readily available) piece detailing any claimed inaccuracies etc.? I would really like to read that too.
On a related note, the 170,000 lb tractive effort figure has been reported to be controversial. I am not clear on why. If we assume that the original figure of 152,206 on 57-inch drivers was correct, then all N&W needed to do was to increase the pressure in the front (low pressure) cylinder for “simple” operation from about 92 psi to about 122 psi, now on 58-inch drivers. Given the fact that in purely simple operation the boiler could supply 300 psi steam, and then the front engine can reduce the steam pressure before admitting it to the cylinders, this doesn’t seem to be a problem (other than as related to adhesion, as discussed above). (For a total of 166,000, you’d need about 116 psi in the front cylinders.)
2179? Why that one? Or do you mean 2197, the one used in the steam-versus-Diesel tests in the early 1950’s? If you want 2197, I think there are some nice pictures on the Virginia Tech site.
The avatar transfer is pretty easy, but to get something decent you need to scale down the file the right way and probably sharpen it. I you want to e-mail me the pic (or send me a URL where I can find it), I will prepare it as an avatar and send it to you (and can give you instructions on how to change it).
Big Jim, I guess if 2156 is your favorite, you are in luck!
I have this fantasy about winning the Powerball, and going back to get my M.S. in mechanical engineering, and writing my thesis about the restoration of 2156, for which I would be able to provide the seed money. You will note that no less than Wick Moorman has an interest in 2156. I figure if we get it running, he will see to it that we have a place to run it, at least occasionally. Maybe even lend us a big cut of coal hoppers to make it interesting?
Builder’s photos of 2156 are floating around out there. I got a fairly nice original (I think) 8x10 print on eBay for a reasonable price a month or so ago. It’s the same image linked to in electronic format in the Wikipedia entry on 2156. I think Virginia Tech has the negative (probably 8x10 film).
Same the avatar file from the e-mail by right-clicking on it and saving it to a local drive (C: or whatever). Come here, sign in, and click on “Update Profile” near the top of the page. Then click the “Enable avatar” radio button (probably already done). Then click the “Browse” button and find the file you just saved, and use it.
