I remember looking at this in the Complete Collection - I'll look a bit later and see if I can find it again.
If there is reduced or zero overbalance, something has to counteract the nosing tendency caused both by piston thrust and inertial load. In the article in question, it was noted that stiff lateral compliance was provided for both the leading and trailing truck, resisting (with the longest possible moment arm) the tendency for the chassis to yaw about the axis of the main driver.
Naturally this force is applied at the pivot pin of the lead truck, and at the rear of the two-axle trailer, giving a longer effective 'wheelbase' and, more directly, greater resistance in curves or lateral track displacements. Ideally the drive would be separated from the guiding, with the drivers given a bit more flange clearance and the steering being done mainly with the leading and trailing trucks (and the lead driver axle given a bit of controlled lateral motion to absorb shock of any insufficiently-spiraled curve or turnout, but probably not as much as on a more 'conventional' locomotive.
The drawback to this approach is that the effective wheelbase being longer, the locomotive is also stiffer and more prone to derail -- including if it encounters any small lateral displacement in the track which a diesel would easily and quietly accommodate. If I remember correctly 611 was notorious for finding these and 'announcing their presence'.
I don't. As far as I know the N&W Class J is perfection itself. :)
The difficulty is there are multiple masses to balance, The wheels, the main rods, and the connecting rods. Forward and aft as well as up and down resultants. Seem to remember an article in Trains a long time ago discussing the N&W's J's which have relatively small drivers and their design efforts in controlling the various forces. The trailing truck had issues in countering the forces from the power stroke wanting to twist the locomotive and putting side thrust against the rails. The J was "stiff" according to the article and had some issues with curves. Anyone remember this article?
Serious question for Chris- Have you ever considered making railroad themed greeting cards out of some of your photos? There is a photographer here in town that does that with photos of old buildings, bridges, landmarks and such. I think there would be a good market for railroad greeting cards that don't involve a 3/4 wedge shot of an SD70.
Thanks to Chris / CopCarSS for my avatar.
Deggesty Semper Vaporo Deggesty Yes, Mr. Weston was faster and stronger than Chris! What did he do with the rods after he caught them? Concerning counterweights, is there still some pounding even with the best practice of counterweighting? Yes, there would still be pounding. The counterweights are not in the same plane as the drive rods and so the wheel has a "wobble" in the plane of rotation. Some wheels had counterweights on the back side of the wheel near the drive pin (which also had to be counterbalanced) to try to even out the wobble. Some even had weights on the wheels on the opposite side of the engine trying to counterbalance the weights on the first side to even out the wobbles. That is one reason for the larger weight near one edge between the drive pin and the main counterbalance weight. There is also pressure applied from the drive rods/side rods in making the wheels rotate, and that pressure is uneven during the rotation; alternately pushing on the bottom of the wheel and pulling on the top of the wheel (in forward motion, the opposite in reverse) and it is not 'continuous' either, but relatively sinusoidal, that cannot be counterbalanced and produces additional pounding. Thanks, Steam Forever, I had long had the understanding that it is not possible to perfectly counterbalance the wheels so that the weight on the (very small) area of contact with the rail is always the same. I had not thought of the wobble in the rotation plane, but it follows that such would exist unless the boxes were so tight as to prevent it--and then would possibly be so tight as to prevent rotation of the axle. Perhaps I should ask my daughter to find my copy of The Locomotive Up To Date, and bring it down to me?
Semper Vaporo Deggesty Yes, Mr. Weston was faster and stronger than Chris! What did he do with the rods after he caught them? Concerning counterweights, is there still some pounding even with the best practice of counterweighting? Yes, there would still be pounding. The counterweights are not in the same plane as the drive rods and so the wheel has a "wobble" in the plane of rotation. Some wheels had counterweights on the back side of the wheel near the drive pin (which also had to be counterbalanced) to try to even out the wobble. Some even had weights on the wheels on the opposite side of the engine trying to counterbalance the weights on the first side to even out the wobbles. That is one reason for the larger weight near one edge between the drive pin and the main counterbalance weight. There is also pressure applied from the drive rods/side rods in making the wheels rotate, and that pressure is uneven during the rotation; alternately pushing on the bottom of the wheel and pulling on the top of the wheel (in forward motion, the opposite in reverse) and it is not 'continuous' either, but relatively sinusoidal, that cannot be counterbalanced and produces additional pounding.
Deggesty Yes, Mr. Weston was faster and stronger than Chris! What did he do with the rods after he caught them? Concerning counterweights, is there still some pounding even with the best practice of counterweighting?
Concerning counterweights, is there still some pounding even with the best practice of counterweighting?
Yes, there would still be pounding. The counterweights are not in the same plane as the drive rods and so the wheel has a "wobble" in the plane of rotation.
Some wheels had counterweights on the back side of the wheel near the drive pin (which also had to be counterbalanced) to try to even out the wobble. Some even had weights on the wheels on the opposite side of the engine trying to counterbalance the weights on the first side to even out the wobbles. That is one reason for the larger weight near one edge between the drive pin and the main counterbalance weight.
There is also pressure applied from the drive rods/side rods in making the wheels rotate, and that pressure is uneven during the rotation; alternately pushing on the bottom of the wheel and pulling on the top of the wheel (in forward motion, the opposite in reverse) and it is not 'continuous' either, but relatively sinusoidal, that cannot be counterbalanced and produces additional pounding.
Thanks, Steam Forever, I had long had the understanding that it is not possible to perfectly counterbalance the wheels so that the weight on the (very small) area of contact with the rail is always the same. I had not thought of the wobble in the rotation plane, but it follows that such would exist unless the boxes were so tight as to prevent it--and then would possibly be so tight as to prevent rotation of the axle. Perhaps I should ask my daughter to find my copy of The Locomotive Up To Date, and bring it down to me?
I do not remember if it was on this thread or another one, but I recall a mention of the possibility that a wheel may slip on its axle, and thus no longer be quartered. I understand that drivers are keyed to the axle, and thus should not be able to slip; am I correct? (The book also describes the process for locating keyways in both axles and wheels.)
Johnny
BaltACD Rocket J. Squirrel for President
Rocket J. Squirrel for President
Not a bad choice, considering what's out there.
My God, are they the BEST we can do?
Sorry, off topic, WAY off topic. Last I'll say about it.
And my compliments to CopCarSS on that stunning photograph! No, film ain't dead yet, but how long it has to live is open to conjecture. I've had to retire most of my camera collection 'cause there's nothing to feed 'em anymore.
Never too old to have a happy childhood!
Firelock76Don't worry, "My Little Pony" is produced in Canada. Actually not a bad show for kids at all, lots of good little life lessons in it.
And like most good cartoons, has a ton of references and jokes that are aimed at those a bit older than the targeted demographic.
But to get back on point - look at Chris' other Flickr shots. All good* stuff.
*-understatement. His stuff is simply amazing.
It's been fun. But it isn't much fun anymore. Signing off for now.
The opinions expressed here represent my own and not those of my employer, any other railroad, company, or person.t fun any
Murphy Siding zugmann Wizlish No, the only surprise is that anyone would consider associating 'Rainbow Dash' and any percentage of 'cool' in the same context...Wink Who do you think said the 20% quote? Sometimes I'm worried that I'm not up to date on American culture. Other times I'm just worried about American culture.
zugmann Wizlish No, the only surprise is that anyone would consider associating 'Rainbow Dash' and any percentage of 'cool' in the same context...Wink Who do you think said the 20% quote?
Wizlish No, the only surprise is that anyone would consider associating 'Rainbow Dash' and any percentage of 'cool' in the same context...Wink
Who do you think said the 20% quote?
Sometimes I'm worried that I'm not up to date on American culture. Other times I'm just worried about American culture.
Don't worry, "My Little Pony" is produced in Canada.
Actually not a bad show for kids at all, lots of good little life lessons in it.
DeggestyConcerning counterweights, is there still some pounding even with the best practice of counterweighting?
There is an analogue, although it is less a 'pound' than a cyclic reversing force on the wheel concerned, and in part this is because a reciprocating locomotive isn't like an IC engine where the crank supports can be rigid and longitudinal motion minimized via thrust bearings).
Theoretically with zero overbalance and proper wedges all the effective rotating mass can be compensated. There is still (considerable) inertial force fore and aft, which would cause pounding if there were any slack in the axlebox 'fit' or in the rod bearings, but we assume for the moment there is not.
What then remains is the resultant in the cross-plane, what used to be the source of 'hammer blow', where the 'perfection' of balance in rotation now results in rocking imbalance because some components of the 'balance' are further outboard than others (cf. the center of mass of the counterweight in the main vs. the center of mass of the eccentric crank). Because there has to be suspension to handle cross-level adhesion (and ideally this would involve equalization too) this implies there is some force that raises or drops one side relative to the 'fulcrum' on the other side, and this manifests as a cyclic vertical force.
Interestingly, although Woodard did not call upon this as a reason to keep rods as far inboard as possible (as in the unitary machinery support) the principle remains valid for high-speed design.
Some additional reduction of mass in the wheelrims can be addressed via the method used in the older Burlington 10-coupled engines: putting some of the rotating balance 'inboard' on the axle between the bearings, or even centered. (This works very well if the Langer gear balancer is also expected to be used.) This will reduce the mass arm of the balance out in the wheelrim as fulcrumed at the opposite wheeltread, and while the rod force still remains unbalanced (in fact, increased as the rotational-balance weight moves further apart from the rod centerline) the net amount of force for hammer-blow reduces. One price for this is that greater care has to be taken against the driver 'slipping quarter' relative to the axle.
Of course for most service this sort of thing is overkill. Where it becomes significant is when relatively high horsepower is to be developed at corresponding high speed from a workable locomotive ... particularly an unconjugated duplex (or a Withuhn duplex that has practical chassis and bearing implementation for that speed and power!). Adhesion at the limit in a duplex may be greatly compromised by the residual 'rocking' unloading of one wheel vs. the other.
As noted elsewhere, while very high speeds could be achieved with modern balanced engines on the 'slip track', this may not translate into balance when full thrust is on the engine. The vertical component of piston thrust can't of course be balanced with any static method, and while 'dynamic' methods to compensate do exist, they tend to be tricky and somewhat expensive to implement ... and their failure might likely produce catastrophic results faster than any agency could compensate. This is not "that" great on an engine with sensible rod angularity, but it can certainly be measured, and to me it makes sense to set the engine default balance, as Voyce Glaze did, to provide 'perfect' balance at the combination of speed and vertical thrust corresponding to the maximum design train at maximum design speed (under the average conditions that would apply when actually operating a train at that speed). Of course all that compensation goes in the main, as that's where the vertical thrust manifests, and you put it as far inboard as you can to minimize the cross-level effects (trusting to your main-pin and pin-seat designs to handle the offset forces).
WizlishNo, the only surprise is that anyone would consider associating 'Rainbow Dash' and any percentage of 'cool' in the same context...Wink
zugmannYes, that's Dash. Considering all the cartoon/anime/video game avatars I've had on here the past 10+ years, I doubt anyone would be surprised
No, the only surprise is that anyone would consider associating 'Rainbow Dash' and any percentage of 'cool' in the same context...
Firelock76Hey Zugmann, when did you turn "Brony?" Your avatar's "Rainbow Dash!" How do I know these things? My informants are everywhere.
Yes, that's Dash. Considering all the cartoon/anime/video game avatars I've had on here the past 10+ years, I doubt anyone would be surprised. Informants, eh? Heh. No comment on that one!
zugmann Murphy Siding Yeah, yeah, yeah. But can you prove you're now 20% cooler? Of course I am. It says right there.
Murphy Siding Yeah, yeah, yeah. But can you prove you're now 20% cooler?
Of course I am. It says right there.
Hey Zugmann, when did you turn "Brony?" Your avatar's "Rainbow Dash!"
How do I know these things? My informants are everywhere.
Changing a tire should have negligible net effect. The distribution of new mass is even around the center of rotation, but the off-centre mass is the same. Yes, the ratio might change a bit, but your average driver set weighs about 8 tons per axle. New tires might add another 150 pounds tops per axle, or about 1%. At the rates of revolution we see in steamers compared to the high rates for much smaller automobile tires, that 1% is essentially forgettable. Mind you, the final say goes to ye olde steam locomotive.
CopCarSSOne question regarding balancing. How was balancing adjusted when the steel tires were changed?
Murphy SidingYeah, yeah, yeah. But can you prove you're now 20% cooler?
Chris- When you take the next step and make a railroad themed calendar, sign me up for one.
zugmann Murphy Siding I'll agree with the amazing part. Chris did my avatar for me. Otherwise I would have had to have one of my kids do it for me and I'd probably end up with an avatar of Homer Simpson saying "doh". Well, if you want...
Murphy Siding I'll agree with the amazing part. Chris did my avatar for me. Otherwise I would have had to have one of my kids do it for me and I'd probably end up with an avatar of Homer Simpson saying "doh".
Well, if you want...
The counterweights balance out the forces generated off-axis as the driving wheels spins. Of course, it gets much worse at speed. Think of a spinning tub in your washing machine where all the heavy wet jeans end up on one side of the drum....disaster. The machine ends up through the wall, the floor, on its side, broken into pieces. The crank and attached rods make the spinning driver want to hop up and down in concert, much like an auto tire that is out of balance. Casting, or bolting on, a counterweight on the opposite side to the crank and bearing/rods comes close to zeroing out those unwanted effects. Close...not completely.
That's a very fetching image up at the top. Would be great on a wall. Here's my HO scale version taken a few years back.
Mookie Chuck - I do like clocks and the more art deco the better. I see Chris has a couple of regulator clocks. I sold a couple of those, old school clocks and mantel clocks (and crank phones) at an antique show I worked years ago. Brings back fond memories. Chris has an amazing variety of great pictures. Always fun to look thru his albums.
Chuck - I do like clocks and the more art deco the better. I see Chris has a couple of regulator clocks. I sold a couple of those, old school clocks and mantel clocks (and crank phones) at an antique show I worked years ago. Brings back fond memories.
Chris has an amazing variety of great pictures. Always fun to look thru his albums.
She who has no signature! cinscocom-tmw
I dont think the balancing was to the degree that changing the steel tire made any difference... the steel would be very uniform in thickness and width (unlike changing an automobile rubber tire where the rubber might very considerably in wall thickness or have "blobs" of enough weight to cause problems at high speeds.)
Semper Vaporo
Pkgs.
Mookie I usually like the time and not how the clock works but on this one - I have watched video of the Big Boys at top speed and it always thrills me to see how fast those side rods move and how efficient the whole engine looks. That's a lot of clock going down a track.
I usually like the time and not how the clock works but on this one - I have watched video of the Big Boys at top speed and it always thrills me to see how fast those side rods move and how efficient the whole engine looks. That's a lot of clock going down a track.
If you like clocks, click Chris' picture to get to his Flikr page and click the right arrow to get to a couple of interesting clock shots. That is not to mention some other great non-railroad subject matter. Chris has been pretty busy the past six months or so, much to the enjoyment of anybody who slides through his Flikr contents.
-ChrisWest Chicago, ILChristopher May Fine Art Photography"In wisdom gathered over time I have found that every experience is a form of exploration." ~Ansel Adams
Wizlish Here is a shot of the 4-4-0 in question (when it was still classified C80) Interestingly enough, when these were renumbered into class 12, in 1924, they were given the Z classification (meaning obsolete and likely soon to be retired). Their subsequent life certainly did not bear that out!
Here is a shot of the 4-4-0 in question (when it was still classified C80)
Interestingly enough, when these were renumbered into class 12, in 1924, they were given the Z classification (meaning obsolete and likely soon to be retired). Their subsequent life certainly did not bear that out!
You have started talking about one of my favourite subjects...
I think the classification of NSWGR locomotives is not clearly represented in the usual references. In this case, I think the letter C replaced the number (at first 79, later 80 after 79 was converted to a 4-4-2 tank locomotive, making 80 the lowest number in the class), rather than being appended to it.
The letter classes were awarded in order of the number of locomotives in stock in 1889: 77 "A" class 0-6-0s, 70 "B" class 2-6-0s and so on the C being the most common passenger locomotive. For those interested, the smallest class ("U") consisted of two Baldwin 4-4-0s built 1877 and 1879.
When the letter classes were introduced, a list was published showing the old and new classes together, and that seems to have become"stuck" historically.
The photo is probably more interesting.
The engineer who adopted the alphabetic classification, William Thow, started on a program to rebuild the fleet, and had "builder's photos" of the resulting rebuilds taken.
In the case of 144, a new boiler with a deeper Belpaire firebox and pitched higher was fitted. The upper cab side, which had just been open, gained the side sheets with the circular opening which were a Thow "trademark". The Belpaire firebox was not applied to the earliest rebuilds of A class 0-6-0s, so this photo would date to the early years of last century, after 1901.
1210 looks pretty much like that today, although it has an electric headlight.
Peter
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