A lot of those "not so great" jobs disappeared with the steam locomotives. As for pride in their work; the N&W men could truly say that those were their engines! Something which could not be said of the LaGrange and Schenectady products which replaced them.
CZ, you caught the Jawn Henry! (First photo). That is the first picture I have seen of the roof!
Both great shots.
Thanks,
NW
friend611I know about the tandem rods on 611 personally because she still had them after the January 1956 wreck. I will have to seek out how long she kept them after that.
You should be able to find that out in Louis Newton's "Rails Remembered' Vol.3. He goes into detail about the single rods.
.
NorthWest CZ, you caught the Jawn Henry! (First photo). That is the first picture I have seen of the roof! Both great shots. Thanks, NW
Thanks. It would have been very nice if we had a great camera at that time, but at least we had one. I was standing on the overpass and noticed it moving and the other steam power just added to the picture. We got to see it in helper service also east of town. The first week in August 56 was a great time to visit since there were no diesels.
CZ.
http://s197.photobucket.com/user/City_train_usa/slideshow/1950%20Era%20Steam?sort=6
This is the PRR which owned a portion of the N&W.
http://s197.photobucket.com/user/City_train_usa/slideshow/PRR%20Steam?sort=6
A few of the NKP which the N&W purchased
http://s197.photobucket.com/user/City_train_usa/slideshow/NKP%20Steam?sort=6
BigJim friend611I know about the tandem rods on 611 personally because she still had them after the January 1956 wreck. I will have to seek out how long she kept them after that. You should be able to find that out in Louis Newton's "Rails Remembered' Vol.3. He goes into detail about the single rods.
The 611 still had the tandem rods in August of 56 as you can see, but they were probably removed after the J's were pulled from passenger service. It is amazing to me they removed the tandem rods since they were balanced so well and this must have changed the balance at least a small amount at speed. I do remember seeing the J running in excursion service extremely fast a few times.
CZ
CZ,Several, but not all, of the J's were converted to the single rod configuration before they were taken out of passenger service. You need to read the book that I suggested.
BigJim CZ,Several, but not all, of the J's were converted to the single rod configuration before they were taken out of passenger service. You need to read the book that I suggested.
Thanks Jim. I will see if I can find that book.
Hi ..
Tandem rods taken off - that sounds like one of those ultimate simplifications applied to steam during the last of service which were not with a view of further maintenance perspectives but just for keeping rndown engines running for a few more miles or months , no matter how , or almost .
Does anyone have details what a rod they put on in replacement of the tandem rod ? You wouldn't mean to say they just took the outer one off and left the inner one on , don't you ?? ( O-M-G )
The main pin would have thanked for *that* and it would have upset the whole distribution of steam and inertia forces .
Looking forward to some interesting documents from some 60 years ago -
Regards
Juniatha
If you look at the Js that were converted, the hub on #3 axle is considerably larger on the single rod locos. It should be because the forces from #2 axle to #3 and #4 must now be handled by one set of bearings instead of two. In addition, the crankpin on #4 axle is much shorter on the single rod locos, which would reduce the bending moment on the #4 crankpin and also reduce the chance of fracture.. There was a good reason to get rid of the tandem rods. Perhaps this was one of them.
I'll try to see if any drawings exist at the NWHS archives regarding this change. I believe about four Js were changed: 611, 605 and two others IIRC.
Added 9/7 - After searching the NWHS archives database, there are more than 20 drawings that appear to address the Class J's single connecting rods. I'll be in Roanoke next weekend for the archives work session so I may be able to take a look at some of them.
feltonhill If you look at the Js that were converted, the hub on #3 axle is considerably larger on the single rod locos. It should be because the forces from #2 axle to #3 and #4 must now be handled by one set of bearings instead of two. In addition, the crankpin on #4 axle is much shorter on the single rod locos, which would reduce the bending moment on the #4 crankpin and also reduce the chance of fracture.. There was a good reason to get rid of the tandem rods. Perhaps this was one of them. I'll try to see if any drawings exist at the NWHS archives regarding this change. I believe about four Js were changed: 611, 605 and two others IIRC. Added 9/7 - After searching the NWHS archives database, there are more than 20 drawings that appear to address the Class J's single connecting rods. I'll be in Roanoke next weekend for the archives work session so I may be able to take a look at some of them.
Great information. Thanks for the update. If you can, see if you can find any reason for the updates to the J class so late in their service life. Did any failures or maybe cracks showing up on the rods of any J class locomotives cause this modification??
CAZEPHYR wrote Sep 7 2013
>> If you can, see if you can find any reason for the updates to the J class so late in their service life. Did any failures or maybe cracks showing up on the rods of any J class locomotives cause this modification?? <<
Me , too - and I will add another "?" to it in regards to all that high speed high revving records of this locomotive class , allegedly having reached better than the very 531 rpm which 'metric diameter speed' requires , 178 km/h for 1778 mm wheel diameter in this case .
Reduction of bending moment on #4 driven axle pin by having a much shorter pin with conventional rod arrangement should be the least of an argument since that pin in any case was the taking the least of steam ( piston thrust ) and mass forces in the drive ; shortening of main pin could not make up for it's relief of bending moment by 50 % with the tandem rod arrangement where con rod acts on pin *between* two coupling rods #2 to #3 drivers .
Juniatha Reduction of bending moment on #4 driven axle pin by having a much shorter pin with conventional rod arrangement should be the least of an argument since that pin in any case was the taking the least of steam ( piston thrust ) and mass forces in the drive;
Reduction of bending moment on #4 driven axle pin by having a much shorter pin with conventional rod arrangement should be the least of an argument since that pin in any case was the taking the least of steam ( piston thrust ) and mass forces in the drive;
This is very true, but it may help to consider the #4 pin in context; look here (sorry if you have to squint!):
I am still looking for an adequate online drawing of the single-rod arrangement; I'm sure Dave (feltonhill) can provide one, showing just how far inboard the single-rod arrangement would be.
shortening of main pin could not make up for it's relief of bending moment by 50 % with the tandem rod arrangement where con rod acts on pin *between* two coupling rods #2 to #3 drivers.
This may be a situation where the stiffer 'eye' fork in the forward end of a #2-#3 rod would make up for the equivalent in the tandems, while preserving a 'straight' thrustline from the main back to the #3 pin. Every little bit of mass reduction outboard in the rodwork helps!
I'm going to wait for the measured drawing and see what the moments work out to be...
Hi Overmod
1 . >> This is very true, but it may help to consider the #4 pin in context; look here (sorry if you have to squint!): <<
Squint ? why squint ? Well , ok : you know , I know the arrangement of tandem rods , I wrote my note because of that ; so what are you intending to convey with that drawing ?
2 . >> This may be a situation where the stiffer 'eye' fork in the forward end of a #2-#3 rod would make up for the equivalent in the tandems, while preserving a 'straight' thrust line from the main back to the #3 pin. Every little bit of mass reduction outboard in the rodwork helps! <<
I wrote it does not make up for a 50% relief - that's not a >> little bit << at all .
>> the stiffer 'eye' fork in the forward end of a #2-#3 rod would make up for the equivalent in the tandems <<
Actually not - no . ( Btw , 'using' a wide bearing to prevent bending of pin would ask for jamming of bearing - not very desirable an idea ; on the contrary , with roller bearings spherical bearings were used in European applications of roller rods ; I know earlier Timken applications used cylindrical bearings , not sure if they wouldn't have changed for - more demanding to fabricate - special bearings , too , had steam continued )
How should that have worked out when that rod end in any case is acting on the pin at just one side of the con rod , not on both ? It would have been different only if you really had a widely forked end to main or coupling rod in such a way it *comprises* each the other on the pin , really providing a straight-through connection of con and coupling rods . However , nobody has so far mentioned this was the case here ; talk was of *conventional* arrangement where as known coupling rod line up was towards wheel side of pin *all through* and con rod connection to main pin was outside main coupling rod end - in any w/a . The forked end would *still* submit the concerning rod to bending moment since the pin would give more on outer bearing surface ; if at all , I would therefore highly recommend to apply the widely forked end to the shorter , stiffer coupling rod . Any of these arrangements however would mean letting go the special occasion offered in a second axle drive of an eight coupled type such as 4-8-2 and 4-8-4 ( 4-8-0 too , yes-ok , well .. ) that is captured by the tandem arrangement of main coupling #2 to #3 drivers and btw having but one type of coupling rod for all-around the engine .
Are we supposed to be numbering the posts in this thread? I've lost count -- can someone go back and put them in if desired?
Juniatha 1 . >> This is very true, but it may help to consider the #4 pin in context; look here (sorry if you have to squint!): << Squint ? why squint ?
Squint ? why squint ?
Squint because it's an itty-bitty copy of a drawing with very fine lines, and it could be difficult to read as posted.
Well , ok : you know , I know the arrangement of tandem rods , I wrote my note because of that ; so what are you intending to convey with that drawing ?
The arrangement of the tandem rods on the N&W J class. For everyone reading this thread who is *not* familiar with the specific arrangement of tandem rods on those locomotives.
... Btw , 'using' a wide bearing to prevent bending of pin would ask for jamming of bearing - not very desirable an idea ;
Just to mention: so would lateral deflection of a thin-section rod, but I will leave that point until I have better historical information. Note that in most of the Timken roller-rod applications I'm familiar with, there is a spherical mounting between the roller-bearing assembly and the rod eye. I had always thought such provision to be highly desirable if not necessary for American thin-section roller-bearing rods.
In any case, I'n not sure I understand the point. There would be separate, opposite tapered roller bearings in each 'side' of the forked eye. Each one is thin (rather dramatically thin, for the applied load, in the N&W drawings I have seen). I am not sure how this is supposed to be prone to jamming merely because the fork is wide enough to accommodate a full main-rod bearing.
on the contrary , with roller bearings spherical bearings were used in European applications of roller rods; ...
Do you mean SKF? I believe their spherical roller bearings were used both for axleboxes and rods -- didn't Alfred Bruce discuss the differences in his book somewhere? They are certainly well-suited to the requirements of railway service...
I know earlier Timken applications used cylindrical bearings , not sure if they wouldn't have changed for - more demanding to fabricate - special bearings , too , had steam continued )
Give me a reference for this -- I don't remember any Timken bearing that was not tapered-roller in this service. (There were cylindrical rollers in part of some of the trailing-truck lateral-accommodation mechanism, including the truck on the Four Aces demonstration 4-8-4, but that doesn't really 'count' ;-}) In fact, one of the touted advantages of Timken bearings was that any wear could be accommodated merely by adjusting the outer race relative to the inner. These were certainly 'special' bearings -- very thin, very large ID, etc. -- but I doubt anything more "special" would have been required had steam continued.
How should that have worked out when that rod end in any case is acting on the pin at just one side of the con rod , not on both ? It would have been different only if you really had a widely forked end to main or coupling rod in such a way it *comprises* each the other on the pin , really providing a straight-through connection of con and coupling rods . However , nobody has so far mentioned this was the case here ;
That is more or less exactly what I thought I was mentioning (although no, I don't yet know that was the case here.). And yes, I would definitely prefer forking the 'receiving' end in the #2 - #3 rod, not the main.
... talk was of *conventional* arrangement where as known coupling rod line up was towards wheel side of pin *all through* and con rod connection to main pin was outside main coupling rod end - in any w/a . The forked end would *still* submit the concerning rod to bending moment since the pin would give more on outer bearing surface ; if at all , I would therefore highly recommend to apply the widely forked end to the shorter , stiffer coupling rod . Any of these arrangements however would mean letting go the special occasion offered in a second axle drive of an eight coupled type such as 4-8-2 and 4-8-4 ( 4-8-0 too , yes-ok , well .. ) that is captured by the tandem arrangement of main coupling #2 to #3 drivers and btw having but one type of coupling rod for all-around the engine. All good. Who has a link to a clear picture of the arrangement on a Niagara? That might be an interesting comparison to both N&W styles.
... talk was of *conventional* arrangement where as known coupling rod line up was towards wheel side of pin *all through* and con rod connection to main pin was outside main coupling rod end - in any w/a . The forked end would *still* submit the concerning rod to bending moment since the pin would give more on outer bearing surface ; if at all , I would therefore highly recommend to apply the widely forked end to the shorter , stiffer coupling rod . Any of these arrangements however would mean letting go the special occasion offered in a second axle drive of an eight coupled type such as 4-8-2 and 4-8-4 ( 4-8-0 too , yes-ok , well .. ) that is captured by the tandem arrangement of main coupling #2 to #3 drivers and btw having but one type of coupling rod for all-around the engine.
All good. Who has a link to a clear picture of the arrangement on a Niagara? That might be an interesting comparison to both N&W styles.
( edit some sentences on roller bearings suplemented to be more explanatory )
Just shortly - I'm in a hurry . No numbering in this thread although we could start it .
>> Just to mention: so would lateral deflection of a thin-section rod,<<
It did – yet with the proportions , shorter pin of large diameter , smaller lateral width of bearing , it simply didn’t cause a problem . On scrutinizing inspection , white metal bearing would have had to be found having worn tapered – and this again inevitably caused progressive wear since full area and uniform pressure load was no more realized in such a bearing , from then on causing inwards end to wear faster when working light , outward end when working hard , all in all working towards a convex wearing pattern that was conductive to premature squeezing out of oil ; with these bearing having had no protection against loss , actually this being part of the concept , oil consumption was increased , lubricating condition was worsened and overall wear increased . Geometrical inexactitudes by many causes was why most steam locomotives developed slack soon after shopping .
Spherical mounting in roller bearing rod end – that’s another way of taking account of these deflections from right angle .
>> I am not sure how this is supposed to be prone to jamming merely because the fork is wide enough to accommodate a full main-rod bearing. <<
Well , with roller bearings you don’t really cause jamming , you cause overload : because of pin deflection from strictly right angle – we are talking of minutes here , not degrees – the inwards end of the fork wide enough to embrace the con rod big end would run on the less deflecting , the outwards end on the more deflecting part of the pin ; this would cause a bending moment on the rod in question – again since we are talking of minutes : not such a force to bend the rod noticeably , yet it is a bending moment and as such undesirable .
>> I believe their spherical roller bearings were used both for axleboxes and rods <<
Maker notwithstanding , this is correct .
>> tapered-roller in this service <<
Ok , right , they used a lot of tapered bearings . The point is : tapered – with counter-tapering in second race – or cylindrical , no matter which , they all are non-self-adjusting against geometrical errorsas the spherical type does – that’s what counts !
>> arrangement on a Niagara <<
Principally same as in the N&W J class . The point always was to ease bending load on main pin ; with a tandem coupling rod arrangement , the above mentioned deflection of the main pin didn’t matter to load on each the bearings since the deflection was simply transmitted to the #3 pin , which again helped to contain deflection by its own rigidity . The silght remaining main pin bending - always well within elastic limits of course - was transmitted by non-spherical roller bearings to slightly bend high but thin tandem coupling rods without apparent drawbacks .
Got to leave , regards
OvermodI am still looking for an adequate online drawing of the single-rod arrangement
There is a good picture of the 'old' version of tandem rod (with forked main-rod end and heavy sections) in Chapelon's La Locomotive a Vapeur (in Carpenter's translation it is on p.60). The accompanying photo appears to have been taken from a Locomotive Cyclopedia. I don't have a source for a Web-enabled version of either picture to provide as an illustration here. Still looking forward to someone providing either a picture of or a direct Web reference to the N&W drawing(s) that show the detailed single-rod arrangement applied to the Js.
I suspect the N&W version, for reasons already well-discussed, would invert the general arrangement illustrated in Chapelon, with the fork on the forward end of the 2-3 rod (essentially duplicating the layout of the double rods as far as bearings and geometry on the main pin is concerned. I would be tempted to put a single bearing on the rear of the 2-3 rod and carry the 3-4 rod inboard of it, rather than forking the rear in imitation of the double-rod arrangement, which would greatly decrease the lateral offset required for the #4 pin. That would limit the amount of 'direct pass-through' of main-rod thrust to the #4 pin, but should give better balancing at high cyclic rpm...
BTW, there is a good technical drawing of the Schwartzkopff-Eckhardt bogie on pp.110-111 of the Carpenter Chapelon translation; it is Fig. 50.
Let your journey end.
Thank you , Big Jim , for posting this revealing picture !
Now , from what I see , this arrangement clearly is a simplification aimed at easing maintenance , no regards to keep up full rpm speed potential - probably it was realized what had been built into it was a bit above what was actually demanded by daily traffic or by traffic remaining stream hauled by then . This *should* have gone together with new , strengthened main pins of larger diameter , demanding reboring of wheel etc - however had that expense been invested by that time with steam on the way out ?
As promised, I went to Roanoke ths past weekend and looked up about 20 or so drawings of the single-rod version of the Class J's. Unfortunately, three days goes past very quickly, and although i looked at all the drawings, I didn't get a chance to compare them in detail. I was hoping to find an equivalent to the tandem rod drawing that Overmod posted earlier. Apparently, NWHS does not have a single rod version, or maybe it never existed. However, to address Juniatha's comments, it appears that a lot of time was spent on the #2, #3 and #4 crankpin and driver center design revisions, attendant revision to the rod and bearing detail drawings, as well as the eccentric crank lateral position and size (this was perhaps to reduce the angular displacement between the eccentric crank and the first link in the Baker valve gear frame. Beyond that, I can assure all that N&W had a lot of drawings related to this change and they appeared to think through the revision with their usual thoroughness. Overmod, when can you get to Roanoke and give these drawing a good going-over?? I'll be there if at all possible.
Hm-- what about the eccentric crank? When they removed the rod, did the eccentric crank get shifted closer to the engine's centerline? If so, did the Baker valve gear have to shift inward too? But it can't, if the valve stays where it was?
The eccentric crank got moved closer to the locomotive centerline. I don't recall if all of the sideways angular displacement was removed or not. The Baker frame and parts were not moved. I didn't phrase that well earlier.
Feltonhill
What you wrote about N&W taking care to re-design the arrangement is self-understood . This was no toy engine , the mass and steam forces evoked by this engine's drive mechanism were substantial .
What I meant was : did they care to redesign in such a way as to keep *the equivalent* of the tandem coupling rod 2nd to 3rd driver ? From that photo I clearly say : no , they didn't . Why can I say that when I wasn't there ( and you weren't neither , btw ) ? simply because the photo tells me this simplified arrangement was *not up* to the former tandem arrangement as concerns taking up mass forces and distributing them between 2nd and 3rd driver pins - beefed up 2nd driver pin notwithstanding ; a certain beefing up they *had* to do , or the pin without its support by the coupling rod *outboard* the vertical plane of action of the con rod would just have shorn off after some full application of full effort of the engine . In case deplorably you thought I would suggest they had used the *same* ( identical , unmodified ) main pin as before , sorry , then you have missed my point .
Since you can neither post drawings nor give a detailed description nor have any data on dimensions before and after the change no substantiated comparison can be made and there is little in just writing N&W took care as they usually did . Everyone will suggest nothing less , as they usually recognize N&W steam . However , it's one thing to design and build an engine with best design in mind for an intended top passenger service and later to keep it *just* running in a late hour of steam traction when there probably was no more need to keep up full speed potential . Also , mind , to keep up degree of mass balancing , this sort of revamping of rods arrangement would have asked for an according revamping of balancing masses in wheels and thus wheels counter weights should have been modified - how would you suggest this be done in a cast steel wheel without casting new wheels ? Yes , I know , you could always take *away* mass from balancing masses - yet to replace a tandem rod arrangement by this sort of a conventional rods arrangement would rather ask for *increasing* wheels counter balancing masses . Now you might reply : they could bore out and fill with lead - I tell you the British Railways had a lot of trouble with lead in counter balancing weights getting brittle , loose and leaving : how much more trouble would it have provided with higher rpm in a *much* heavier engine on jointed rails ?
addenda :
>> it appears that a lot of time was spent on the #2, #3 and #4 crankpin and driver center design revisions ..<<
Why then didn't they apply the much better ( for conventional rod system !) coupling rods arrangement with articulation joints on middle coupling rod to which the outer coupling rods reached ? This allowed for all coupling rods to be aligned in one common longtudinal center line , no offset , no full thrust taken up by intermediate pins and transmitted to next rod sideways of engaging rod . This would also have provided for main pin to be further shortened - or con rod big end to be wider .
I think they preferred to retain existing end coupling rods - to wich the former tandem middle rods could also be stored as possible replacements , since all of these were same . Carefully as it may have been carried out , this marks the change over as a budget revision - such as all too often was the case everywhere in the later days of steam with diesels ante portas .
As to the 'offset' : with a shorter main pin it was no problem to adjust seating and dimension of eccentric crank and bearings and center line of eccentric rod to keep valve gear unmodified from everything in the valve gear mounting onwards . A slight offset from strictly longitudinal plane was acceptable in a long enough eccentric rod - with the simplified coupling rods arrangement , it seems this was no longer needed . No problem at this point at all .
Also , mind , to keep up degree of mass balancing , this sort of revamping of rods arrangement would have asked for an according revamping of balancing masses in wheels and thus wheels counter weights should have been modified - how would you suggest this be done in a cast steel wheel without casting new wheels ?
Juniatha ... how would you suggest this be done in a cast steel wheel without casting new wheels ?
Ralph Johnson discusses this and so does Chapelon.
The cast pockets for counterbalance and cross-balance in the driver are oversize, usually divided into 'cells' or segments by cast-in partitions, and closed off with a welded cover plate -- my T1 drawings have some interesting notes on how the welding was to be done, indicating that tinkering with the weight was not an uncommon procedure!
The material used to cast the weights is specifically chosen so it would not shrink, or become friable. Once it was set in the pockets, it is not going to move. The alloy Chapelon cites is an alloy of lead and antimony, although he does not specify the exact percentages; it would be easy enough to determine. In a modern application you'd probably use 'crankshaft-weight' material (tungsten-based) or perhaps even, like the 747, depleted uranium (probably in this application as the oxide) embedded in layers of castable metal.
Yes , I know , you could always take *away* mass from balancing masses - yet to replace a tandem rod arrangement by this sort of a conventional rods arrangement would rather ask for *increasing* wheels counter balancing masses.
I would be tempted to expect the difference to be minimal, as determining the section and construction of a single rod possessing the same mass and mass distribution as the pair of tandem rods taken together is not a difficult exercise. While there may be some lateral difference in the bending stress in the pin, it would shift inboard, not outboard (the contribution of the 'inside' tandem rod in hammer blow being considerably less than the outer one) so I would expect removing mass would be the more common. It might be desirable to drill out and recast a portion of the 'advance' mass for cross-balance if that method is used, but that would be comparatively simple.
I would suspect that machining additional space in a cast wheel center would be relatively trivial, as would welding partitions into any opened core spaces or exposed fillets, etc. This without measurably impairing the functional strength of the wheel disc, or weakening the rim support of the tire.
I can think of ways to jig this so it could be done on assembled wheelsets, e.g. sets ready for adjustment in the quartering machine, or rigged for dynamic spin balancing. Extending or reshaping weight pockets is nowhere near as critical as main-pin alignment... even should actually placing or ensuring distribution of mass in the pockets at balance time prove to be.
Now you might reply : they could bore out and fill with lead - I tell you the British Railways had a lot of trouble with lead in counter balancing weights getting brittle , loose and leaving : how much more trouble would it have provided with higher rpm in a *much* heavier engine on jointed rails ?
See comment above about alloying. As a further note, even if the proper alloy were to be beaten loose, and even if it were to be beaten around rather than primarily held to the outside radius of the pocket by 'centrifugal force', how would you propose to get it out past the 360-degree-seal-welded cover plate?
If there should prove to be a problem with casting new alloy into recesses in old alloy, I would try preheating, perhaps with gas blanket or submerged-arc-style fluxing; getting effective homogeneity between old and new mass is just not a major metallurgical issue as far as I can see.
Ralph Johnson mentioned that American problems with 'disappearing lead' in balance masses were an issue -- in the Nineteenth Century -- and noted that issue was substantially addressed relatively early on in the Twentieth. It might be amusing to hear from our UK (ex-)brethren about why they seem to have continued to have problems -- that might wind up reminiscent of the arguments often made in some British circles, even today, about why equalization is a pointless expense for imaginary gain on locomotives (and especially between coupled and trailing axles!), or why Franklin adjustable wedges are a ridiculous waste of money when hardened liners alone do the job so well. ;-}
In the addenda: Is a slight offset in the eccentric rod permissible with Multirol needle bearings? I'd think you'd have to skew the eye alignment slightly to keep the bearings parallel-loaded -- and in any case at high speed your buckling moments might be exaggerated (the tendency toward lateral deflection was bad enough already at high speed, ne?) The catch with longer offset on the crank itself (assuming you keep most of the crank mass itself as far inboard as possible) is that the longer outboard portion will itself act as a longer 'cantilever' and deflect worse in high-inertia situations, if made for minimum impact (pun not intended) on hammer-blow momenta.
Overmod ,
I have written what I wanted to comment about this matter and have nothing to add to it . I wrote it *could be done* but it was *not the same* in technological level . The replacement was essentially a low-tech application and - sorry - what you post are some quite theoretical and some pretty optimistic scholarly views and expectations about how to do this – arguably aiming at my commenting these again and so on like a ping-pong game : why some propositions are not practical or why they don't offer what you expect of them and why I have not described in detail these or in fact any other theoretically possible solutions , suggestions or substitutions – last not least : why some of them are quite ill-founded . This has become burdening , especially since I feel you just want to involve me in some sort of hassle or controversy no matter what . So , I'm not going to enter this sort of discussion , especially not when about pondering if and how a low-tech solution *could* be executed , simply because with the concerning photograph it has already become blatantly plain and clear it *was* done , full stop .
Something else : you seem to develop a habit to put at question anything but anything I post . If you have different views on everything please feel free to retain your view , only : please don't expect me to defend , justify , explain or prove my comments thereupon - I simply don't have that much time to spend on these things . I'm awfully sorry yet it appears I finally need to put that clear . Objections like boring out and refill by casting an earlier cast structure and expecting this to form a solid unity ignores thermal expansion / shrinking and consequential thermal stresses . Same about the idea of welding a plate to the casting to cover up a 'hole' with lead filling . Ok , so the fill-up material might not get lost , yet when having become disintegrated by beats form rail joints , pieces of it are flung around , disintegrating more of the mass , while the engine goes through the paces accelerating until reaching a speed where centrifugal forces will have pieces rest in radial position ( while that still does *not* secure their position when rattling over rail joints while loose pieces may be at 0 , 90 , 180 , 270 degrees position relative to piston or any arbitrary position in between . Misinterpretations like , to quote >> While there may be some lateral difference in the bending stress in the pin, it would shift inboard, not outboard << Now , *I* *never* wrote it would be “shifted outwards” , this is an imputation ! and combined with an incorrect assumption of yours that taking away the outboard part of the tandem rod would cause but >> some difference in bending stress << but some ? dramatic underrating ! ( btw what do you mean by “lateral difference” ? the stress on pin by piston force or mass inertia already *is* a vector force and not laterally but longitudinally directed ! then : how could exactly *this* rod modification result in stress to be “shifted inwards” ? if that could have been done it would have been great for it would set just the very part of the pin in fact most submitted to those forces free of stress - especially since the simplified rods layout *did* substantially increase shearing forces ! ) More examples could be added yet
If Ralph Johnson still is your standard let me just ask : why then did Baldwin repeatedly have trouble with balancing of big engines like the Atlantic Coast Line 4-8-4 , why did they cast wheels with precaution extra counter weight blocks to be machined to suit only after manufacturing the wheel sets , why did the Pennsy have trouble with the Baldwin Duplexi and so on ...?
Overmod , look ; what Johnson had written , he did more than 1/2 a century ago - technology has long since moved on and with absolutely fantastic progress . So , in earnest , what do you want to prove by instigating controversies about trivial details of a low-tech simplification of a once well composed rods system ?
Let’s agree to drop that .
Hello , Prof Overmod ,
Sorry if this may not live up to your expectations – yet it appears this has to be addressed :
I have written what I wanted to comment about this matter and have nothing to add to it . I wrote it *could be done* but it was *not the same* in technological level . The replacement was essentially a low-tech application and - sorry - what you post are some quite theoretical and some pretty optimistic scholarly views and expectations about how to do this – arguably aiming at my commenting these again and so on like a ping-pong game : why some propositions are not practical or why they don't offer what you expect of them and why I have not described in detail these or in fact any other theoretically possible solutions , suggestions or substitutions – last not least : why some of them are quite ill-founded . I’m sorry , this has become burdening , especially since I feel you just want to involve me in some sort of hassle or controversy no matter what . So , I'm not going to enter this sort of discussion , especially not when about pondering if and how a low-tech solution *could* be executed , simply because with the concerning photograph it has already become blatantly plain and clear it *was* done , full stop .
It seems to me you have developed a habit to put at question anything but anything I post . If you have different views on everything please feel free to retain your view , only : please don't expect me to defend , justify , explain or prove my comments thereupon - I simply don't have that much time to spend on these things . I'm awfully sorry yet it appears I finally need to put that clear . Objections like boring out and refill by casting an earlier cast structure and expecting this to form a solid unity ignores thermal expansion / shrinking and consequential thermal stresses . Same about the idea of welding a plate to the casting to cover up a 'hole' with lead filling . Ok , so the fill-up material might not get lost , yet when having become disintegrated by beats transmitted to wheels from rail joints , pieces of it are flung around , disintegrating more of the mass , while the engine goes through the paces accelerating until reaching a speed where centrifugal forces will have pieces rest in radial position ( while that still does *not* secure their position when rattling over rail joints with loose pieces may be at 0 , 90 , 180 , 270 degrees position relative to piston or any arbitrary position in between . Misinterpretations are not helpful , like , to quote >> While there may be some lateral difference in the bending stress in the pin, it would shift inboard, not outboard << Now , *I* *never* wrote it would be “shifted outwards” , this is an imputation ! and combined with an incorrect assumption of yours that taking away the outboard part of the tandem rod would cause but >> some difference in bending stress << but some ? dramatic underrating ! ( btw what do you mean by “lateral difference” ? the stress on pin by piston force or mass inertia already *is* a vector force and not laterally but longitudinally directed ! then : how could exactly *this* rod modification result in stress to be “shifted inwards” ? if that could have been done it would have been great for it would have set free of stress just the very part of the pin in fact most submitted to those forces - especially since the simplified rods layout *did* substantially increase shearing forces ! ) More examples could be added ..
If Ralph Johnson still is your standard let me just ask : why then did Baldwin repeatedly have trouble with balancing of big engines like the Atlantic Coast Line 4-8-4 , why did they cast wheels with precaution extra counter weight blocks to be machined to suit only after manufacturing and assembling the wheel sets ( obviously to take care of not-too-small tolerances in wheel castings ?) , why did the Pennsy have trouble with the Baldwin Duplexi and so on ...?
No insult intended - only , could we agree to drop that .
With regards
Overmod Juniatha ... how would you suggest this be done in a cast steel wheel without casting new wheels ? Ralph Johnson discusses this and so does Chapelon. The cast pockets for counterbalance and cross-balance in the driver are oversize, usually divided into 'cells' or segments by cast-in partitions, and closed off with a welded cover plate -- my T1 drawings have some interesting notes on how the welding was to be done, indicating that tinkering with the weight was not an uncommon procedure! The material used to cast the weights is specifically chosen so it would not shrink, or become friable. Once it was set in the pockets, it is not going to move.
The material used to cast the weights is specifically chosen so it would not shrink, or become friable. Once it was set in the pockets, it is not going to move.
Juniatha,I wonder why you have a "bee in your bonnet" (x 2?)? Your question was properly answered and you get mad about it? What's up with that?
Our community is FREE to join. To participate you must either login or register for an account.