Big Jim
Your photo again is interesting and provides facts - *that's* what gets this matter on .
Why do I have a bee under my bonnet ? guess everybody is talking of hybrids and bio-fuel and all that , so I thought I might try bee-power - no ?
Earnestly : sorry , usually I am a gently agreeable person and maybe I should better not have replied at all , yet after taking so much , enough is enough . I think I'm prepared to discuss next to most almost everything and then some concerning steam locomotives , however if things are just being questioned for the like of questioning that's not getting things forward .
My 'question' was not really a question but my way of trying to make think twice about the *wisdom* of doing things the way they were done at that time *long ago* (!) .
You were right about your remark concerning LC 47 and the hollow castings ready to take up filling material to suit . I suspect these may have been early efforts at some minimum of unification of castings for possible use in various locomotive types - and thus naturally adjusting counter weights to each loco's reciprocating masses . However , as you look at these massive structures it is again hard to think these were calculated for *zero overbalance* as had also been suggested earlier - together with an aberrant idea of the influence of rpm speed on balancing .
I'm certainly not suggesting any idea of how the N&W 4-8-4 *was* balanced and how it was re-balanced with the revised rods arrangement since I do not have documentation about that . All I wrote was the revised single rod arrangement was *not as good* as the original tandem rod arrangement - that's all and I keep that up on sound engineering logics and reasons evident . I really don't see what needs to be questioned about that and why .
With regards
Juniatha
You did not need to comment twice; once would have been sufficient. And relax, none of my comments are intended to be about you.
I only quoted Johnson as a reference to how balance weights were secured, not as a reference on balancing. I do not think there have been dramatic changes in the tech of balance-mass securing since that time, but I am always prepared to be mistaken and receive enlightenment. If you think we need to disagree on matters of balance-mass integrity, we can do so.
The ACL R1 problems have been well-described, and aside from preceding the publication even of Johnson's first edition, if you were questioning his knowledge, were a failure caused by reliance on then-newly-modified AAR standards (which turned out to be ghastly wrong!).
Knowing what I do about the practicalities of casting locomotive driver centers in the 1940s in the United States, I see nothing strange in allowing 'extra' areas for provision of balance mass. Certainly we can do better today.
Please tell me more about where PRR had nonunderstood balance problems with the T1 Duplexes -- all the ones I know of involve suspension and difficulties associated with the duplex configuration itself.
I am still waiting for clear-dimensioned drawings, or a picture accompanied by direct measurements, of the arrangement applied to 611. Once I have actual, measurable evidence, I can fairly decide for myself the degree to which the mods were actually 'cost-cutting'. That is by no means to say that the single-rod mods weren't made with lower expense in mind, or that anyone else is wrong to conclude so. Only that I want better proof.
Overmod
>> You did not need to comment twice; once would have been sufficient. <<
Obviously not – I *did* write once and it seems it was *not* sufficient – however let’s drop it for good now .
>> The ACL R1 problems have been well-described, and aside from preceding the publication even of Johnson's first edition <<
If engineering wisdom contained in his book only came to R.J. at a time the book was being published , then you have a point there .
>> I see nothing strange in allowing 'extra' areas for provision of balance mass.<<
That wasn’t the point . Point was *way* provision machined *subsequently* into *existing* wheels were to be *filled with lead* ( with byways touching how well this method could provide for re-adapting cross balancing properly )
>> Please tell me more about where PRR had nonunderstood balance problems with the T1 Duplexes <<
That’s exactly the sort of pharisaical argumentation I mean : I never suggested R.J.’s scope of engineering was confined to nothing but balancing . You know perfectly well where the problems with the Baldwin T1 design were , yet you insinuate a meaning in my words I didn’t intend and which wasn’t there .
( on # 611 ) >> the degree to which the mods were actually 'cost-cutting'. <<
That’s introducing a new point ! So far , focus was on *technical quality* of the simplified rods arrangement . You shift argument from your original position questioning my decent remark the modification was a step down in quality – not just as compared with the original tandem rod system but also in relation to an *in line* coupling rod alignment with knuckles . By intention not going into details , I briefly touched implications of this simplified arrangement which for a full rebuilding really would have demanded quite thorough changes to certain components ( for example just short of everything on main drive wheel set ) as compared to a probably simplified realization in view of probably eased demands with steam traction in its final stage .
If you feel my reaction was too harsh , I’m sorry . However , if you might want to put yourself in my place see if you would like to post something only to have another person go over your text scrutinizing for words that *could* be misinterpreted and promptly writing critical comments on what you didn’t mean and didn’t write . Or , as when I posted those drafts of a SE Mallet and Triplex variation as a contribution to matters *deep firebox behind drive wheel sets* you wrote a laconic ‘wipe out correction’ on an allegedly faulty position of Delta truck without offering an alternative , less so an improvement . Or as when , without substantiating your assumption , you called it a ‘misconception’ when I commented on higher flange forces with Mallet locomotive running in reversed set-up with fixed engine first – note according with the work of Heumann and others still providing basis for understanding railway vehicle guiding and tracking .
However , as I said in the beginning : I think we should better drop these controversies for good now – fighting issues on details of locomotive of over 60 years ago is not what I’m here for , it’s neither educating nor enlightening .
This is not meant to be an exhaustive reply to all the preceding details. It‘s intended to be additional perspective regarding how N&W worked and why, and also clear some of the dust that’s been raised on this thread..N&W converted at least four of the Class J 4-8-4's from tandem intermediate rods (between #2 and #3 driving axle) to single rods from about 1952 to 1956 (600, 605, 610, 611). How did this evolve and why did they do this?Initially, all modern 4-8-4's that were equipped with roller bearing rods used the so called tandem rod connection between #2 and #3 axles. In addition, because of this configuration, all of them had relatively long crankpins on #4 axle. The examples are:N&W Class J (1941-1950)ATSF 3776 and 2900 classes (1944 estimated)NYC S1a, S1b and S2 Niagaras (1945)C&O J3a (1948).Further, there were a few 4-8-2's that were equipped with roller bearing rods, either as-built or retrofitted. Two known examples are:NYC Mohawks (a few, probably around 1943-1945)UP 4-8-2 (one or two estimated, date unknown)Because all railroads used the same method (tandem rods), this was likely the industry standard for handling the forces that had to be distributed through the running gear, particularly between axles #2 and #3 of a 4-axle engine set.N&W revised the Class J rods to do away with the tandem rod setup on four locomotives, but according to this discussion, there was no obvious reason. I believe there was a missing link that has not been considered, the N&W Class A 2-6-6-4.In 1948, N&W ordered the last five Class A’s and had them equipped with roller bearing rods. The design of these rods merits a closer look. The main rod drove on axle #3 of each engine set. Therefore, the force had to be distributed to two additional axles, the same as the 4-8-2s and 4-8-4s, except the axles were forward instead of behind the main crankpin. These rods operated in a more constricted lateral space on the Class As than they did on the 4-8-4s, so there wasn’t room for tandem rods. N&W and Timken designed an single intermediate rod instead. There was no precedent for this because none of the 4-6-6-4's built were equipped with roller bearing rods. This modification is visible in photos of the last five A’s. The rod hub on #2 axle is clearly larger than the rod hub on #1 axle. The design was ultimately successful because the final Class As were no slouches in the freight-moving department. If you want to hear what the last group of Class A’s performance sounded like (shameless plug here), a new CD, Time Freight, is available from the O. Winston Link Museum gift shop and the N&W Historical Society. See their websites.As part of my drawing check last week, I noticed that there was some commonality between the Class A and Class J rods, particularly the single intermediate rods. However, the Class A drawings were generally dated 1948, and the Class J comments were added from about 1952 through 1956.It looks to me as if N&W took what it learned from the Class A rod design, and applied it to the Class Js. It would be a design improvement if the #4 crankpin could be shortened by placing the rod closer to the wheel. All railroads noted maintenance problems around the #4 crankpins. This would also improve one of the equations used to cross-balance the Js (i.e., keeping the rotating mass closer to the locomotive centerline).If there is any doubt that this application was also successful, four of the last five Class J’s retired had this rod modification. In other words, all of the modified Js lasted to the end, regardless of their construction date.
If anyone is interested , the PRR T1 counterbalancing problems were not a secret. The problem was apparent on one of the two prototypes. T1 6110 was selected for investigation by the Test Department. Coming into the tests 6110 was cross-balanced with 19% of the reciprocating weight balanced. When it was first run on the test plant, the longitudinal vibrations were too severe to continue. No. 6110 was then statically balanced. After completing this modification, PRR estimated that 56% of the reciprocating weight was balanced. This greatly reduced the longitudinal vibration, although it was still severe approaching 80 rpm (about 19 mph), the critical period of the dynamometer spring. This did not interfere with the tests because the lowest speeds runs were 160 rpm or 38 mph. The above is paraphrased from the Altoona test report.
feltonhillThese rods operated in a more constricted lateral space on the Class As than they did on the 4-8-4s
feltonhillso there wasn’t room for tandem rods.
Juniatha That’s introducing a new point !
That’s introducing a new point !
Not intended as such, in the previous context ... but as I said, I'm not commenting on any further aspect of the matter right now, and I agree that we should suspend further discussion for now ... especially as I do happen to agree with most of your points in general principle.
... see if you would like to post something only to have another person go over your text scrutinizing for words that *could* be misinterpreted and promptly writing critical comments on what you didn’t mean and didn’t write . Or , as when I posted those drafts of a SE Mallet and Triplex variation as a contribution to matters *deep firebox behind drive wheel sets* you wrote a laconic ‘wipe out correction’ on an allegedly faulty position of Delta truck without offering an alternative , less so an improvement . Or as when , without substantiating your assumption , you called it a ‘misconception’ when I commented on higher flange forces with Mallet locomotive running in reversed set-up with fixed engine first – note according with the work of Heumann and others still providing basis for understanding railway vehicle guiding and tracking .
Strange -- I distinctly remember apologizing for all three of these specific issues.
Of course, I did in fact propose alternatives concerning the trailing truck design and geometry, and would have no difficulty going into my usual MEGO-inducing detail on that particular subject if necessary. But as I thought we had agreed, that's not really a major issue for an Internet board.
I am not quite sure why you disparage Johnson on balancing and then try to quote Heumann as a current authority on vehicle guiding. (For the rest of the people who care to follow the general topic, here is a convenient introduction to the relevant history; it's by no means current but will at least get interested people up to speed on some of what's involved.)
I thoroughly agree ... with the peripheral note that this particular discussion of rods is NOT so much 'ancient history' as a discussion of the state of the rods now on 611, and how they might best be restored (or improved) when the locomotive is...
timz,
First question - yes, but I need to check the available drawings regarding centerline distance to find out for sure. The Class J center-to-center distance is probably greater than the Class A. I don't live in Roanoke, so it will be October before I get there again.
Second question - I don't know about impossible, but it certainly looks improbable.
A picture is worth a thousand words:
Corresponding drawing for the class J is E45409, and the drawing for the intermediate pin arrangement is E45413. Neither of those appears to have been scanned... DAVE?????? ;-}
The J eccentric crank with single-rod arrangement is D45407, and the matching eccentric rod with SKF bearings is D45404 (and if anyone wants it, the main pin is E45408)
feltonhillso there wasn’t room for tandem rods.As long as the A's main rod drove the third axle, wouldn't "tandem rods" be impossible?
No, you could do them quite easily; there is just comparatively little point on a six-coupled engine. You'd have a spacer the width of the bearing assembly in the main-rod eye keeping the dual rods separate and parallel at the rear pin. The whole shebang would still be outboard of the main-to-front rod, and that rod would still constrain the effective power going from the main drivers to the leading and trailing sets... the whole point of the tandem rods is to distribute thrust across the two 'middle' pins when it is so high as to imperil a single main pin's structure, and when the 'second' main pin is itself driving at least one additional pin... so at least eight-coupled to get reasonable gain from all those 'extra' bearings and fittings.
Originally, the term "tandem rod" meant the side rod from the main driver to the next rearward one was in line with the main rod-- the same distance from the locomotive centerline. Roller-bearing rods are usually sort of "tandem" in that sense: one side rod inboard of the main rod and one outboard. You don't think that's part of the definition of "tandem rod"?
timz Originally, the term "tandem rod" meant the side rod from the main driver to the next rearward one was in line with the main rod-- the same distance from the locomotive centerline. Roller-bearing rods are usually sort of "tandem" in that sense: one side rod inboard of the main rod and one outboard. You don't think that's part of the definition of "tandem rod"?
The classical "tandem" or "extended" main rods (that is how Alfred Bruce terms them, somewhat tellingly) use a separate bushing across a forked main-rod end. The end of the following intermediate rod is the blade in the center of the fork, and so the rods are in line, but the salient point is that the thrust of the main to the intermediate crankpin passes only through the bushing, not the main-driver crankpin. This "about halving the direct load on the conventional main crankpin" (p.215) So while I am not certain whether 'tandem' refers to the doubled pin area, or to the distribution of the thrust across multiple crankpins, that is the area of the arrangement to which 'tandem' refers.
Notably, N&W does not refer to the double-intermediate-rod setup as "tandem rod" -- they call it 'dual' in all the drawing references. Chapelon does not hesitate in using 'tandem' to refer to this setup on the J class, but he mentions clearly what the tandem arrangement does elsewhere (LLAV, p.59) and has a good illustration (fig 8, p.60). Alfred Bruce of Alco pointedly avoids using 'tandem' when he describes the dual-rod arrangement as on the J and the Niagara (fig 37, #9), but his illustration of the tandem arrangement (fig. 37, #8) shows just about what Chapelon's does. [Note that just the inverse of this, with the blade being the main-rod big end and the fork being on the forward intermediate-rod end, is what I was kinda expecting for the N&W J "single rod" configuration...]
Note that this setup is quite different from the 'articulated' rods used by Woodard et al. in the Twenties (see Bruce, pp.218-219), which are sometimes seen referred to as tandem rods. In these, the side rods are all kept in a line by putting an extension on the rear of one rod, with a knuckle pin, and a fork on the engaging end of the following rod. These knuckle pins were notorious for causing problems, and no one appears to have been sorry to see them superseded. Bruce has an interesting reference to the 'updated' version of this used on the UP 800s (his fig. 29, #3) which you will note contains the same idea of intermediate bushings (but free-floating this time, and with no knuckles; Chapelon has a good picture of this from the side (fig. 29, p.91), and of one of the bushings with all the lubrication holes drilled in it (fig. 31, p.92)
Overmod this setup is quite different from the 'articulated' rods used by Woodard et al. in the Twenties (see Bruce, pp.218-219), which are sometimes seen referred to as tandem rods.
OvermodIn these, the side rods are all kept in a line...
timzWoodard called the A-1's rods "tandem", didn't he?
I don't have a direct reference, but articulated rods predate the Berkshire design. In any case, dual rods would be much less useful on a locomotive driving on the third coupled axle (as the doubled rod would go forward, not back). I'm pretty sure that when Woodard said 'tandem' it had to do with sharing thrust load over multiple crankpins...
See US patent 1,803,987 for Woodard himself on this subject (admittedly as late as 1928, with the patent issuing in mid-1931).
Overmod,
I don't set the priorities on the scanner/printer at the archives Sales orders come first, everything else is second. I did pull some of these drawings two weeks ago and they appear in good condition. We'll see what happens next month.
Well now, if I place an order in the next couple of days, how quickly will it get done? I hadn't considered that the 'scanned' drawings were the ones for which orders had been received ... but now that you mention it, that would make sense... anyone else out there care to 'sponsor' scanning one of the drawings, and contribute to a good organization at the same time?
The archives work sessions are three days a month. Next one is Oct 10-13. The price of D and E drawings is not expensive. If you order the drawing through the Commissary (which I would highly recommend) , it will go into the queue with the other sales orders. The guys that run the scanner will probably get it completed within the work session (they're good, and they also work between sessions on their own).
friend611But we do have the comfort that most of 1218's parts were retained, and there may be a chance that 1218 might run again.
Lois, we need that to happen! How hard would this be, assuming all money was available?
Linked here is a prior post with a picture of J1 606.
friend611 the only A known to make any run on this division.
Lois, That is incorrect as it has been noted years ago on the N&WHS mailing list that 1205 was indeed in Shenandoah. It was also related to me by an engineer that the Class A's would on occasion make a trip up the Valley. But, it was a rare occurrence and being without cab signals they had to run under signature of the Div. Supt.
.
Lois,The real question should have been...How did the 606 get to Shenandoah to begin with? Perhaps Mason has the train sheets that would tell, maybe not. Keep in mind that an "Extra" can be anything. A lite engine, a freight, a passenger, work train, etc. With no more to go on than "Extra 606", everything at this point is supposition. No one knows. My guess is that there could have been a reason that the normal engine assignment for a northbound passenger train fell down in Roanoke and 606 just happened to be the only thing available at the time to take its place. Once in Shenandoah it was taken off, turned and sent back to Roanoke by first available means, whatever that may have been.
Regarding the Class A, something told me to go back through my files and it took me a while to find it, but, #1205 was the A that was seen in Shenandoah. This was during WWII. Again, if I was to take a guess, it would be troop train related. Sorry for any confusion.
Poking the hornet's nest again because I can't remember if this issue was ever settled:
N&W revised the Class J rods to do away with the tandem rod setup on four locomotives, but according to this discussion, there was no obvious reason.
friend611Waiting for an announcement on a certain matter regarding N&W Y6a 2-8-8-2 2156...lois
Is this the one in Saint Louis? They can't possibly be talking about bringing that one back to life, can they?
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