Thanks for your feedback about the (now deleted) comment and the apparent cynicism behind it, Juniatha. You are quite right to expect to be welcomed in this forum as your sex is irrelevant, and so is your age. I happen to have enjoyed your participation, being able to speak only for myself, and I am grateful you continue to post here, some of the unpleasantness notwithstanding.
I ask you to continue to be courageous and determined if only so that I can continue to benefit from those qualities as they allow you to provide your insights about steam locomotives.
Crandell
Juniatha Ok, everybody First of all, thank you John for applying some good common sense to this non-railway topic. For all who might have wondered: ok, I'm not so young anymore, my 35th is coming up in these weeks, yet I might be considered born too late for steam in respect of American RRs. However, I have made no bones about my having lived in Germany for most of my life and since re-unification in 1990 there have been a few last chances to see 'live steam' on East German DR and in Poland, and some other countries, besides steam events which were quite frequent in Germany and in Britain during the 1990s. Yet, all that would not have triggered anything if it had not been for my dad's influence, I think I have allowed that to be felt in some remarks. I want to ask in reverse: to go posting in what is known to be a 99.9 % men's forum - why on earth should someone take on a female gender and expose oneself to some abusive remarks like this if it wasn't so? [...] This is self-fullfilling closed circle argumentation that doesn't relate to reality and doesn't want to.
Ok, everybody
First of all, thank you John for applying some good common sense to this non-railway topic.
For all who might have wondered: ok, I'm not so young anymore, my 35th is coming up in these weeks, yet I might be considered born too late for steam in respect of American RRs. However, I have made no bones about my having lived in Germany for most of my life and since re-unification in 1990 there have been a few last chances to see 'live steam' on East German DR and in Poland, and some other countries, besides steam events which were quite frequent in Germany and in Britain during the 1990s. Yet, all that would not have triggered anything if it had not been for my dad's influence, I think I have allowed that to be felt in some remarks.
I want to ask in reverse: to go posting in what is known to be a 99.9 % men's forum - why on earth should someone take on a female gender and expose oneself to some abusive remarks like this if it wasn't so? [...] This is self-fullfilling closed circle argumentation that doesn't relate to reality and doesn't want to.
Um.... you might want to reconsider your appeal to logic... look where it got these guys...
CROWD: A witch! A witch! A witch! We've got a witch! A witch!VILLAGER #1: We have found a witch, might we burn her?CROWD: Burn her! Burn!BEDEMIR: How do you know she is a witch?VILLAGER #2: She looks like one.BEDEMIR: Bring her forward.WITCH: I'm not a witch. I'm not a witch.BEDEMIR: But you are dressed as one.WITCH: They dressed me up like this.CROWD: No, we didn't... no.WITCH: And this isn't my nose, it's a false one.BEDEMIR: Well?VILLAGER #1: Well, we did do the nose.BEDEMIR: The nose?VILLAGER #1: And the hat -- but she is a witch!CROWD: Burn her! Witch! Witch! Burn her!BEDEMIR: Did you dress her up like this?CROWD: No, no... no ... yes. Yes, yes, a bit, a bit.VILLAGER #1: She has got a wart.BEDEMIR: What makes you think she is a witch?VILLAGER #3: Well, she turned me into a newt.BEDEMIR: A newt?VILLAGER #3: I got better.VILLAGER #2: Burn her anyway!CROWD: Burn! Burn her!BEDEMIR: Quiet, quiet. Quiet! There are ways of telling whether she is a witch.CROWD: Are there? What are they?BEDEMIR: Tell me, what do you do with witches?VILLAGER #2: Burn!CROWD: Burn, burn them up!BEDEMIR: And what do you burn apart from witches?VILLAGER #1: More witches!VILLAGER #2: Wood!BEDEMIR: So, why do witches burn? [pause]VILLAGER #3: B--... 'cause they're made of wood...?BEDEMIR: Good!CROWD: Oh yeah, yeah...BEDEMIR: So, how do we tell whether she is made of wood?VILLAGER #1: Build a bridge out of her.BEDEMIR: Aah, but can you not also build bridges out of stone?VILLAGER #2: Oh, yeah.BEDEMIR: Does wood sink in water?VILLAGER #1: No, no.VILLAGER #2: It floats! It floats!VILLAGER #1: Throw her into the pond!CROWD: The pond!BEDEMIR: What also floats in water?VILLAGER #1: Bread!VILLAGER #2: Apples!VILLAGER #3: Very small rocks!VILLAGER #1: Cider!VILLAGER #2: Great gravy!VILLAGER #1: Cherries!VILLAGER #2: Mud!VILLAGER #3: Churches -- churches!VILLAGER #2: Lead -- lead!ARTHUR: A duck.CROWD: Oooh.BEDEMIR: Exactly! So, logically...,VILLAGER #1: If... she.. weighs the same as a duck, she's made of wood.BEDEMIR: And therefore--?VILLAGER #1: A witch!CROWD: A witch!BEDEMIR: We shall use my larger scales!
John
Well, well Mr. Tmidget. I promised myself I would NEVER hide behind the anonymity that this site provides, viewing it as a priviledge not to be abused, but I feel like abusing it RIGHT NOW! As a former Marine I posess a quite blistering vocabulary (think R. Lee Ermey in "Full Metal Jacket") I'd like to turn on you, but I'd get myself banned for life from the site, and at any rate the only thing that would come through is ******* or ********* or other asterisk laden substitutes. I suppose TMidget refers to your intelligence, and not your size. Do us all a favor and grow up a bit before you enter this site again. There, you just recieved a .75 caliber round ball from the Firelock. Don't make me fix the bayonet next time. If you can't accept the fact a woman has the grasp of engineering that Juniatha has that's YOUR problem. Wise up and join the 21st Century!
http://www.youtube.com/watch?v=zrzMhU_4m-g
jwhitten Um.... you might want to reconsider your appeal to logic... look where it got these guys... CROWD: A witch! A witch! A witch! We've got a witch! A witch!VILLAGER #1: We have found a witch, might we burn her?CROWD: Burn her! Burn!BEDEMIR: How do you know she is a witch?VILLAGER #2: She looks like one.BEDEMIR: Bring her forward.WITCH: I'm not a witch. I'm not a witch.BEDEMIR: But you are dressed as one.WITCH: They dressed me up like this.CROWD: No, we didn't... no.WITCH: And this isn't my nose, it's a false one.BEDEMIR: Well?VILLAGER #1: Well, we did do the nose.BEDEMIR: The nose?VILLAGER #1: And the hat -- but she is a witch!CROWD: Burn her! Witch! Witch! Burn her!BEDEMIR: Did you dress her up like this?CROWD: No, no... no ... yes. Yes, yes, a bit, a bit.VILLAGER #1: She has got a wart.BEDEMIR: What makes you think she is a witch?VILLAGER #3: Well, she turned me into a newt.BEDEMIR: A newt?VILLAGER #3: I got better.VILLAGER #2: Burn her anyway!CROWD: Burn! Burn her!BEDEMIR: Quiet, quiet. Quiet! There are ways of telling whether she is a witch.CROWD: Are there? What are they?BEDEMIR: Tell me, what do you do with witches?VILLAGER #2: Burn!CROWD: Burn, burn them up!BEDEMIR: And what do you burn apart from witches?VILLAGER #1: More witches!VILLAGER #2: Wood!BEDEMIR: So, why do witches burn? [pause]VILLAGER #3: B--... 'cause they're made of wood...?BEDEMIR: Good!CROWD: Oh yeah, yeah...BEDEMIR: So, how do we tell whether she is made of wood?VILLAGER #1: Build a bridge out of her.BEDEMIR: Aah, but can you not also build bridges out of stone?VILLAGER #2: Oh, yeah.BEDEMIR: Does wood sink in water?VILLAGER #1: No, no.VILLAGER #2: It floats! It floats!VILLAGER #1: Throw her into the pond!CROWD: The pond!BEDEMIR: What also floats in water?VILLAGER #1: Bread!VILLAGER #2: Apples!VILLAGER #3: Very small rocks!VILLAGER #1: Cider!VILLAGER #2: Great gravy!VILLAGER #1: Cherries!VILLAGER #2: Mud!VILLAGER #3: Churches -- churches!VILLAGER #2: Lead -- lead!ARTHUR: A duck.CROWD: Oooh.BEDEMIR: Exactly! So, logically...,VILLAGER #1: If... she.. weighs the same as a duck, she's made of wood.BEDEMIR: And therefore--?VILLAGER #1: A witch!CROWD: A witch!BEDEMIR: We shall use my larger scales! John
Never too old to have a happy childhood!
And Juniatha, you keep on posting young lady! Don't let some troglodite scare you off! I and many others enjoy everything you have to say, you bring a fresh perspective to the site, and every time you post we all learn something, whether some want to admit it or not. Rally 'round, gentlemen! Support our local Steam Queen!
Firelock76 And Juniatha, you keep on posting young lady! Don't let some troglodite scare you off! I and many others enjoy everything you have to say, you bring a fresh perspective to the site, and every time you post we all learn something, whether some want to admit it or not. Rally 'round, gentlemen! Support our local Steam Queen!
In the next forty years (when you will have reached my current age) you will have, I expect, have given much pleasure to the afficionados of steam locomotives as they learn from you.
Johnny
I'm going to say one last thing about "Mental Midgets" insult to Juniatha, that'll be the end of it and hopefully we can get this thread back to where it's supposed to be, such as who built the best looking and why, and other things.
The thing I love (and I don't use the word loosely) about the Forum is the chance to interact and learn from other railfans from across the country and across the "Pond", and maybe from other parts of the world. People I'd never get to meet and converse with under other circumstances. It's a wonderful thing, and thanks to "Trains" magazine to make it possible. I've learned here, I've made friends here, maybe even saved a life here. I've had laughs here too. And I'm sure there's some lonely ones out there who think of the Forum as a lifeline to others who share the same passions.
That being said, there is no, and there should be no room on this site for the angry little gnomes who hide behind a computer screen and cybernet anonymity to be cruel, insulting and otherwise disgusting. We want no cyberbullies here. I'll have no bullies here as much as it's in my power to prevent it. If you want to bully or insult be man enough to put your own name on it, but as a bully is a coward at heart that's not likely to happen.
So, Mr. Tdmidget, I never want to see you here again. And may God forgive you for that vile insult you threw at Juniatha, because I never will.
Y6bs evergreen in my mind
Juniatha;
I post on several forums and belong to a few organizations but I have to say that the railfan community in general seems to have the largest problem of one member having more knowlege on a subject than somebody else. On most forums if someone is presented with new knowlege on a subject dear to them they will acknowlege it and move on.
For some reason when an "expert" in the railfan community is proven to be not as informed as he thought, many times venality and name calling are the result. As was said before, don't let the rantings of the few uninformed influence your decision on posting here. Having said that................
Yeah, I have to agree the Pennsy T1s looked elegant and the Q freighters were hard to beat for that industrial "muscle" look. Many of you might find this interesting: A member of the live steam community built a 1/8 scale Q2 but found that it wouldn't pull a train half the weight that his friends little 2-6-0 would pull. No matter what he did concerning valve timing and throttle application the Q2 would simply spin it's wheels at start up.
When the two engine sets were in time, all was well but as soon as they got out of time massive slipping occurred. His solution was to rebuild the locomotive with the second and third axles cranked and an inside connecting rod between them to keep the engine sets in time. After this modification the Q2 would pull as much as a scale Big Boy or Alleghany.
I read this in an issue of Live Steam about ten years ago and have been wondering if the Ts and Qs were only a connecting rod away from being truly great machines instead of a sad side note to dieselization. Oh well, coulda woulda shoulda.......................................
Pat.
Yardmaster01 When the two engine sets were in time, all was well but as soon as they got out of time massive slipping occurred. His solution was to rebuild the locomotive with the second and third axles cranked and an inside connecting rod between them to keep the engine sets in time. After this modification the Q2 would pull as much as a scale Big Boy or Alleghany.
I have wondered for awhile if, on the duplex drive locos (or articulateds, for that matter), it would have been wise to have only one set of valve gear driving both front and rear piston valves. It would appear impossible for the two engines ever to get significantly out of time, though perhaps the secondary engine would have problems. Or perhaps not. I don't recall anyone's trying this as an experiment.
Ed
Hello Folks
Thank you all for your kind encouragements !
Well , as Firelock wrote – let’s get back to topics steam …
Pat mentioning slipping problem of Duplex cured by inner coupling with drive sets in phase
Doña de la tempestad ! I had thought this to be so !
No kidding , see :
http://railroad.net/forums/viewtopic.php?f=13&t=42536&sid=2a7e2b07633f0a21f71829b129393050
posting of Mon Aug 20 2007; point 4a/b and posting of Mon Sept 03 2007 ; answer to typewriter Q-2 performance , answer to timz - why not 180 °
However , I think crank axles inner coupling only works that well on a model engine since all forces and loads are very much reduced in comparison to surface areas or cross sections since mass is reduced by cube of scale while cross sections only come down by square of scale – i e with a 1:10 model fully true to scale , axle cross sections or bearing surfaces are 1/100 of real engine while mass is but 1/1000 - that is why live steam models can be worked on much lower pressures . Again , I wonder characteristics had become that prominent in a model . In real engines the size and mass of a T-1 inner coupling by crank axles would likely cause a number of problems that in my view would clearly outweigh any advantages of such a disposition as compared to a classic arrangement four cylinder engine with but one instead of two crank axles .
One of the original points promoted by Baldwin with the Duplex concept was reduction of hammer blow and while most of the reduction was to result from partition of cylinder forces , it was also hoped for a lower factor of reciprocating mass balancing necessary when the two drive set would not work in phase . As one author recently wrote , B&O 5600 was supposed to have been equipped with 1 inch difference in wheel diameter between sets in order to prevent the sets to run in phase so to avoid reciprocating masses to add up . I have never read about that anywhere else and if so this would have had sets running in and out of phase in regular intervals and this would not have solved anything . Could anyone shed a light on this odd proposition (if it wasn’t just a tall story by that author) ? Add .: Clearly different driver diameter have in fact been tried on the early Santa Fe 4-4-6-2 articulated boiler engine(s) . This appears to have been an effort to 'balance' the differing configurations in front and rear engine . It can be said in hindsight that the engine(s) were , well , pretty far from succeeding (no matter what driver diameter , yet although it didn't matter much , it didn't help either) .
Even without this strange feature, sets would tend to change relative phases during a start / during a run . This had been noticed by André Chapelon when he had a ride with #5600 during his 1938 visit to the United States (report on journey in Revue Generale) , in short he noted that drive sets of 5600 – and also those of simple expansion Mallet locomotives where the beats of each the sets could be heard – would turn at any relative phasing they happened to have acquired as long as tractive effort was not high , such as during zigzagging through switches to back up to a train . However , when tractive effort was high as in starting a heavy train then the sets would tend to settle to nearly in phase running . To me this seemed curious , at first inexplicable : how could one set ‘know’ what the other was doing ? Trying to visualize in mind mechanical action of piston forces on pins , wheels and axles it came to me that axle torsion was a vital factor in two cylinder engines .
That explained a peculiar behaviour I had noted on (worn out , thus having plenty of play in drives) Decapod engines : when starting , they went into a proper frequency at a certain medium low speed (around 25 mph in this case) where they started nosing ; as speed rose this faded out and the engines gained their habitual straight forward running , with vivid longitudinal oscillation due to low balancing factor of reciprocating masses but laterally stable , without twisting or hunting . If tractive effort of one set of drivers would tend to react on frames so as to alternatingly twist longitudinal axis off line with track axis , then two drive sets could interfere with each other if their piston forces would cause contradicting reactions of frames as it was if the sets would be at or near 180 ° phase relative to each other . This would result in easier slipping as each of the sets could not fully apply adhesion mass without micro slip of one side of wheels – which tends to destroy adhesion (in design of modern high performance electrics great care is being taken to avoid uneven wheel pull per side at any rate) . If the two sets were in phase , however they would work pretty much like one combined set , thus detrimental effect on adhesion would be minimized . I figured , this behaviour should have been markedly more prominent with an engine having two drive sets in one rigid frame than in an articulated engine because with separate , although hinged , frames the drive sets have more freedom individually to inscribe in track in reaction to their piston forces . Still , in some videos of Challenger 3985 running drive sets can be seen to join in phase when running fast or at high output .
What I didn’t have were any reports about how severe this characteristic did make itself noticed in practice . As I interpreted literature on T-1 slippage issue , it was not so much a matter of these engines showing a definite and permanent reduction of adhesion as compared to engines with one drive set and comparable adhesion mass but rather a degree of unpredictability combining with a general trend of reduced adhesion . Positioning the two sets in phase would thus have been vital in any application of inner coupling – however , had the Pennsy attempted it I feel they would rather have chosen an opposed positioning in order to balance out reciprocating masses of each the sets since there was some criticism of the engines oscillating when drive sets were in phase due to low degree balancing of reciprocating masses – consequentially , the Pennsy might have found inner coupling would not help starting while adding more latent causes for damages .
A problem comparable to some extend afflicted three cylinder Pacifics with dual axle drive (inside cylinder worked on first driver) . Although it was generally believed three cylinder engines had a better starting characteristic because of more uniform torque (theoretically , if considered combined !) , this was obviously not so at least in some classes of such engines , such as the British SR Bulleid Pacifics or the 012 class of DB . These engines also suffered from micro slip acting on various axles and wheels alternatively during a turn of wheels thus destroying uniform adhesion of all wheels at all times .
Ed , I understand you suggest to drive valves for both drive sets by just valve gear from one set ?
That way , starting considerations with a locomotive rolling fresh from factory everything would be alright as long as sets remained perfectly in relative phase as set up – and I mean perfectly ! As soon as minor influences make themselves noticed such as differences in tracking , differences in micro slip – not even mentioning a real slip – then the cylinders receiving valve gear control from the other set would start to work at haphazard valve events , opening either too late or too early . Eventually these out of time valve events would probably stop that drive set of further deviation from intended phasing , however only as cylinder work becomes seriously hampered . Valve events would not have enough influence though to re-establish fully correct relative phasing and thus the cylinders controlled by derived motion would have to run at ill-timed valve events . This would affect power output as well as bear heavily on cylinder efficiency .
Flexing of derived motion valve gear was often noted when outside alve gear was used to run a four cylinder compound (one drive) with derived motion to inside cylinders . Valve errors were noticeable to varying degrees in such engines – to disadvantage of power and efficiency . With three cylinder engines , a basically comparable thing was done to avoid inner valve gear for middle cylinder . Again , imperfections and valve errors made themselves noticed in traffic , arguably calling the engine in for running repairs more often than with three independent valve gear sets .
My old saying applies to all these efforts at getting some advantage without paying for it :
Nothin’ gained for free
in design of machinery
And lest we forget about the aesthetic aspects – here’s a painting by Lodlow with colors rearranged by me : Loewy in a Study “Eet has to look like ze aeroplane” Commander pacing a T-1 . Now which color do you like best on the locomotive :
Black
Steely (bluish grey-metallic)
Green (if not exactly Brunswick)
Copper (at dawn – sorry Raymond some green got on your car)
So , what do you say ?
Kind regards
Juniatha
Edit:
Some missing words inserted, some changed for better fitting ones
This had been noticed by André Chapelon when he had a ride with #5600 during his 1938 visit to the United States (report on journey in Revue Generale) , in short he noted that drive sets of 5600 – and also those of simple expansion Mallet locomotives where the beats of each the sets could be heard – would turn at any relative phasing they happened to have acquired as long as tractive effort was not high , such as during zigzagging through switches to back up to a train . However , when tractive effort was high as in starting a heavy train then the sets would tend to settle to nearly in phase running .
Juniatha,I find your comments very interesting. This discussion has come up before with some saying that it didn't and couldn't happen. Listening to hours of tapes of N&W Class A locos pulling hard up the Blue Ridge grade proves the naysayers wrong and that it did happen regularly. Even more moderm videos of the 1218 taken in excursion service show that after starting it didn't take very many rotations for the front and rear engine to sync up.
Not having an engineering background, such as your own, my thought on the cause of this phenomenon was the steam scavenging through the exhaust nozzle or in other words the steam taking the path of least resistance setting up the front and rear engines to run "in sync".
.
The comment about differing driver diameters was intriguing. I remember reading that when PRR put out a Request For Proposal for the T-1, Lima suggested differing driver diameters for each set to prevent them from ever getting in phase.
The green on the T-1 looks best when compared to the other colors. If not a Studebaker Commander, a Greyhound Super Scenicruiser (also a Loewy design) would have looked good on the paralleling highway.
I'd like to suggest that part of this in-phase/out-of-phase discussion may have something to do with what's called "quarter-slip." This phenomenon is caused by the uneven 4-pulse torque curve of a steam locomotive over one revolution of the drivers. One of the peaks is higher than the rest, and if working near the limit of adhesion, the drivers on one engine may slip several degrees in response to this peak.
There are many recordings of the N&W Class A's (2-6-6-4) in both regular service (O WInston Link and Bud Swearer being the best known) and excursion service (1218, with many videos and recordings made). Frequently you hear 4 exhaust beats per revolution, indicating the the two engines are operating in-phase. Other times, the drivers are slightly out of phase and the peculiar and dramatic "double-licks" are heard.
During heavy work on a grade, in-phase working can be heard most easily, and an A can sustain an almost metronome-perfect beat for considerable lengths of time. However, if the quarter-slip phenomenon occurs, the exhaust will drift to an out-of-phase sound (syncopated). Sometimes the exhaust will stay that way, and sometime the two engines will get back in step.
This opinion only addresses whether the exhausts are in-step or out-of-step relative to each other, not that the crankpin locations of each engine are in exactly the same position.
Hi again Juniatha: Your discussion on the cause of articulated and duplex drives getting their drive units out of phase with the front unit tending to slip was most fascinating. I have a viedo tape of the UP Challenger trying to start its train on Altamont Pass while on the way to the Railfair at San Jose some years ago. As the engineer opened his throttle, the lead unit broke loose and slipped like mad for several seconds until it caught its grip and the train started to gain a little speed. I always thought it could be because there was more engine weight on the rear set of drivers . After all, the rear of the engine supports the firebox and many of the other appliances while the front end only supports the front of the boiler and the pilot and perhaps a few appliances. Strangely enough I operate a heavily built brass 2-8-8-4 Yellowstone ( HO Scale ) on my club layout and the same thing happens. The rear set of drivers simply has much more "dig" than the front set which sometimes slips and occasionally just drifts along letting the rear drivers pull the train. I know, I know! There's a world of difference between HO brass and full scale live steam. Still.......
Hi Big Jim and Feltonhill ,
Interesting to read the drive sets of A class simple expansion Mallets did synchronize to that extent . As for ramp work that should indicate the engines were run at high output rate , pretty hard up to adhesion limit – which would correspond with what is known of N&W steam traction . Pressure waves in the long intake and exhaust pipes may have had an influence , although I think frequency of valve openings were too slow in ramp work at adhesion limit , if there was an influence of proper frequency at some higher speed it would have affected output of the hind drive set more than the front one .
Synchronized exhaust beats would be heard at four relative phases front to rear unit – 0 ° – 90 ° – 180 ° – 270 ° of which to my theory 0 ° would be optimum , 180 ° would be worst with 90 ° and 270 ° in between . Since at each quarter there seems to be local optimum , synchronization by micro slip could get ‘trapped’ at 90 ° / 270 ° .
Quarter slip is a slow macro slip that developed at peak torque during wheel turn but was not powerful enough to develop into a full slip before torque entered next low during wheel turn and this was enough to stop that slip . To do that , the slip factor (travel on wheel rim to travel on rail) must remain below a level where adhesion starts to drop severely . Modern synchronous motors electrics use increase in adhesion or rather : friction between wheel tire and rail found under condition of controlled increased slip between micro and macro slip to maximize t.e. as motor rpm can be finely controlled and a very small increase of rpm , indicative of starting full slip , would result in sharp drop of motor turning moment , thus preventing slip to start .
As for steam , main rods worked at varying angles and had a definite length to piston stroke relation ; in consequence approaches to front and rear d.c. were not equivalent and mid-stoke position was not at 90 ° to d.c. That caused unequal distribution and values of peak torque points over wheel turn . Adding up on this were valve timing errors and unequal cut offs / release points . By quarter slip a synchronization ‘trapped’ at one quarter should have moved on to full synchronization , however if a slip started from that position it might more likely have developed into a full slip because there was no better relative position next quarter that could stop the slip .
Hi CSSHEGEWISCH
The idea of having 1 inch difference in diameter sounds intriguing , right . However , what was to be gained by it ? Necessarily the drive sets would periodically go though all relative phases from 0 ° to 360 ° – thus covering all advantageous and adverse relative positions over a relatively short stretch of track . This effectively would have limited safe power output to a rate transmissible in the most adverse relative phasing of the drive sets – or else there would have been periodically repeated wheel slips as that adverse relative phase was being approached . Excuse me , but I think the idea bespoke a lack of finer understanding of interactions between drive sets and was a 'shot in the dark' effort at evoking ‘average’ conditions lest there might be one or the other that were adverse . However , the idea does not answer its consequential effect of all possible relative positions being called up and among these also the worst – no matter which one it was .
As on the T-1 locomotives front unit was said to have slipped markedly more often , and lively so , than rear unit , the locomotives would likely have acquired unequal driving wheel diameters in front and rear unit after some time in traffic – with tread wear difference could well have surpassed 1 inch diameter difference . In fact , steam locos tended to wear tires unevenly -a- over circumference of wheel -b- on different axles in a set of coupled axles . If my theory is correct , such engines with unequal tire wear should have been more prone to slipping than those with freshly turned or new tires as mechanical inexactitudes forced micro slip even at low t.e. working or coasting . Among the last of Decapod steam on DR and PKP I had seen examples supporting this consideration : engines with worn down tires seemed to slip more easily , more frequently and more violently than engines with new or turned tires .
Hi Jim Valle ,
>> The rear set of drivers simply has much more "dig" than the front set which sometimes slips and occasionally just drifts along letting the rear drivers pull the train. <<
Now , that’s appalling ! I mean , it’s plain unsocial , drive sets should work together as partners , each taking it’s fair share of the load ! Guess you should have a serious talk to this slothful front set , maybe bring down the message you could as well consider rebuilding the locomotive into a Berkshire , getting rid of that vain front idler altogether if it doesn’t shape up swiftly now ! Or if that rather rude address doesn’t work , there was a book by – I believe her name if I recall correctly was – Dr. psych. esot. Indiramadra Chandrapendivanughanij and the book’s title was , let’s see .. oh : “Yoga for locomotives with dual drive sets – how to rebalance your flow of energy by realizing and resolving blockades built up in daily working routine” .. or so . It was more aimed at Beyer-Garratt types , though , but I guess a Yellowstone could also …
Well , you see , I have no explanation for this and couldn’t since I don’t know the model . Principally , most HO models tend to start up abruptly like your typical rabbit when it sees a fresh carrot – not like big steamers staging a pathetic crescendo of hissing steam and gathering power prior to gravely setting into sedated movement that more than underlines the gorgeous sublimity , grand royalty and bodacious magnificence that is in a steam locomotive (and besides all that grand theatre , mind you , it can do useful work by simply pulling a train , too – now if that isn’t one stupendous mechano-enigmatic wondermarvel then I don’t know what’s in it that intrigues me again and again) .
Seriously , now
Engine mass on front unit in Mallet type articulateds : yes , I was wondering myself how they could get enough mass on the front engine – until I saw some erecting shop pictures of the front unit frames assembly for UP Challenger : why , they had used something called a ‘back bone’ installed between frames proper . It reminded me of a coquille in size and shape or it looked not unlike a piece of lead inserted in a model locomotive to add up mass . That way , they indeed arrived at practically equal adhesion mass on front drive set as on back drive set . I guess many Mallets used some sort of ‘artificial’ mass augmentation on the front unit – as these were substantial pieces they presented no small increase of engine mass and certainly this was one reason why Mallet type articulateds were never competitive in power output productivity (kW per ton of engine service mass) to rigid frame engines . As for real locomotives , the front unit could still be more prone to slipping because in normal forward running it was this unit that hit a low adhesion spot first . As it started spinning , throttle was usually eased and this way the second unit seemingly never slipped on the same spot although it might have , had throttle and valve gear setting remained unaltered .
As for the T-1 , the class had both drive sets combined in one system of balanced springing while the front bogie was separately sprung – so there should have been no weight transfer from front to back unit by influence of starting t. e. .
Regards
Edit : Remark inserted different tire wear on T-1 having caused difference in actual wheel diameter
I have a question-- did the drivers tend to wear in non-circular patterns? Become slightly elongated or ellipsoid over time? And if so, was there a difference in the wear patterns between drivers in the same set versus drivers in multiple (coupled or tandem) sets? (What I know about any of this would easily fill a thimble-- with ample room to spare :-)
Hi,
I read this fine thread for weeks and Im hppay, that Juniatha is still with us.
Please let me give some remarks to the topic "slippery Duplex Engines".
First of all, as I recall the test reports of the C&O and N&W tests of PRR T1, the T1 was much less slippery than most publications tell. The N&W tests compared the T1 and the J with predictable results: The T1 superseeded the J at sppeds above 75 mph. Especially the N&W reports nothing on "slipping". They did report, that the engineer and tireman hat to learn to work the engine. However, it was a bit more complicated to handle than useal two-cylinder engines.
This is simply due to the task, the T1 was designed for: Haul fast passenger trains on level tracks.
An internal connecting of the due set of drivers could have been successfull. In France, the PLM bullt in 1932 10 engines of 2-4-6-2 wheel arrangement,. This were - of course - compound engines, the low pressure cylinders drove the first two drivers, the high pressure cylinders the second set of three drivers. These engines might have had - as some sources tell - internal rods between the two sets of drivers. The 151A of the SNCF are reported to be quite succesful. The engines lasted till the end of the 50s.
The B&O experimented on their Duplex 5600 with different driver diameters. One set was reduced by one inch, the impact on slipping was none.
However, I doubt if connecting rods on a simple Duplex would be really succesfull. The steam connection of o compound would make more sense.
Hope to read more on this,
McS
I guess many Mallets used some sort of ‘artificial’ mass augmentation on the front unit – as these were substantial pieces they presented no small increase of engine mass
The N&W poured lead into the front engine frames of the "Improved Y5/Y6 classes.
and certainly this was one reason why Mallet type articulateds were never competitive in power output productivity (kW per ton of engine service mass) to rigid frame engines .
With the exception being the above mentioned "Improved Y5/Y6 classes.
John,
Yes they did, at here in NSW they did. it was a phenomenom exhibited by our D-57, D-58 and AD-60 Class locomotives. From what I know, the drivers wore relatively evenly, with a slight worse wear on the main driving wheelset.
The 57s & 58s were three cylinder 4-8-2 heavy goods locomotives and the 60s were 4-8-4+4-8-4 Beyer Garratts, for heavy goods work too. These locomotives would develop what was called 'skidded tyres' which caused rough riding as well as further loss of adhesion.
Look here, http://www.australiansteam.com/nswgrframe.htm, to see what they look like. 5711, 6029, 6039, 6040 and 6042 are the survivors.
Spinner5711 John, Yes they did, at here in NSW they did. it was a phenomenom exhibited by our D-57, D-58 and AD-60 Class locomotives. From what I know, the drivers wore relatively evenly, with a slight worse wear on the main driving wheelset. The 57s & 58s were three cylinder 4-8-2 heavy goods locomotives and the 60s were 4-8-4+4-8-4 Beyer Garratts, for heavy goods work too. These locomotives would develop what was called 'skidded tyres' which caused rough riding as well as further loss of adhesion. Look here, http://www.australiansteam.com/nswgrframe.htm, to see what they look like. 5711, 6029, 6039, 6040 and 6042 are the survivors.
If I understand what you're saying, you're agreeing that the drivers did wear in ellipsoidal patterns..? So my follow-up question is if that's the case, wouldn't that have complicated the traction scenario a bit, not to mention adding additional destructive pounding to the rails? How long does it take for the wheels to wear enough to cause problems? How often were the tires changed out? (And was that enough, or was the damage / wear also to the actual wheel itself?)
BigJim and certainly this was one reason why Mallet type articulateds were never competitive in power output productivity (kW per ton of engine service mass) to rigid frame engines . With the exception being the above mentioned "Improved Y5/Y6 classes.
How?
The "improved" Y5/Y6 produced about the same maximum HP as a big 4-8-4, but the engine weight was close to 70 tons higher.
Well now, several things to talk about. On Juniatha's T-1 color schemes, I've got to go with the green. It's not Pennsy's Brunswick (three parts black, one part green) Green, more like Lionels version of Brunswick Green. Looks better than the real thing anyway. If this keeps up Ms. Juniatha's going to turn me into a T-1 fan. I call it the Pennsylvaniasaurus, after a painting someone did several years ago.
On articulated slippage and "synching", I suppose in the end it wasn't that much of a concern to the RR's that used them, or the type would have been discarded long before the end of the steam era. I remember reading an article in a 1989 issue of "Trains" written by Steve Lee about running the Union Pacific's 4-6-6-4 #3985. Ol' Steve said that "jackrabbit" starting an articulated would cause the water in the boiler to surge back towards the firebox, thus reducing the weight on the front engine and causing slippage. Slow and steady starts were the key.
GP40-2 How?
By being several percentage points higher in efficiency than your 4-8-4.
BigJim GP40-2: How? By being several percentage points higher in efficiency than your 4-8-4.
GP40-2: How?
Juniatha's statement was when comparing total engine weight, a big articulated did not produce as much HP per pound as a rigid frame steam locomotive. The minor increase in efficiency that a compound Y6 may or may not have produced has nothing to do with that statement. The fact is, a Y6's boiler was quite small for an articulated design, about the size of a large 4-8-4, and produced similar peak HP. The Allegheny and Yellowstone Class boilers were much larger and could produce much more steam per hour. The difference between the Y6 and a large 4-8-4 was the Y6 produced peak HP at 20 to 25 mph, while the typical Superpower 4-8-4 would produce peak HP around 60 mph. Peak HP was similar, but the Y6 weighed nearly 140,000 lbs more.
A similar comparison would be to a heavily ballasted 2000 HP SD38 and a relatively light 4200 HP P42DC. The P42DC is producing much more power per pound of locomotive weight compared to the SD38.
but the Y6 weighed nearly 140,000 lbs more.
Closer to 89,000 lbs. but who's counting. And we've seen how a Y6 could out perform an Allegheny and a Yellowstone. There are many ways to express HP ratings in steam locomotives depending on how one wants to spin the doctor.
Comparing other roads mallet locomotives to the rigid frame locos, I will concede Juniatha should be correct. It's just that the N&W Y6 wasn't just anyones old mallet type. Unlike other roads who chose not to develop their locos, the N&W developed the Y class until the very end and what a mallet it was!
And btw, I hever heard of a Y6 (or Class A / J) ever running out of steam so their boilers must be making more than enough steam.
Hi folks Yes, the wheel treads wore circumferentially uneven . That was a consequence of a steam locomotive’s curve inscription with powered axles rigidly in frame and it’s various disturbing motion while running , caused by reciprocating masses (and thus the more so , the less well balanced the engine unit was) . We’re speaking of 1/32 to 1/16 ins between high and low spot in a worn tire , though – nothing to prompt noticeable extra disturbance nor any consequence to track maintenance . For instance , on Decapod engines wheel flanges on the leading coupled axle wore decidedly faster than those of intermediate coupled axles and to a different lateral pattern , too , because first coupled axle was taking a share in guiding the engine in curve – DR Decapod classes were equipped with Krauss-Helmhotz-truck which combined leading Pony truck with lateral motion on first coupled axle so as to level and dampen peak flange forces while fifth coupled axle was laterally moving to run free of flange contact in wider curves or guide itself in sharp curves . Heavier wear on first coupled axle was because it could not inscribe properly in curve but run with flange contact on the outer rail at an angle to rail , thus tread wear was increased over second , fourth and fifth coupled axles . Because longitudinal oscillation , unbalanced reciprocating masses , all coupled wheels showed circumferentially uneven wear of treads as this action could not go without varying degrees of micro slip . As axle bearings and axle box sliding in pedestals developed play , main drive axle also suffered by rattling under the influence of these unbalanced masses , which was destructive not just to bearings wear but also to tire wear if you think of how that axle changed position 4 times per wheel turn , thereby adopting two counteracting positions not strictly at right angle to longitudinal center line , one forward and one backward stop position within the amount of play . Since the coupled axles all showed different patterns of motion on track with engine running at speed , overall wear of wheel tires differed and engines tended to get non-identical drive wheel diameters by accumulating mileage and this disturbed proper adhesion , additional to disturbing knocking action by play in bearings and axle boxes , all combining to make engine slip easier . The valiant Y-6 compound Mallet : I guess what Big Jim has in mind is grade climbing – there is no doubt Y-6 engines lived up to best standards in very heavy ramp work and did so at relatively economic coal consumption . Yet , as this heavy lugging operation necessarily went along at low speeds , equivalent power output was not as high as with running maximum power at speed , like with an A class 2-6-6-4 at 50 mph . To produce some 7000 – 8000 ihp at 20 mph would have called for multi-unit diesel tractive effort and by default that clearly was beyond limits of any 2 x 8 coupled Articulated – Mallet , Garratt or you name it . As some of the Mallet’s engine mass consisted of unproductive mass inserted just to augment adhesion mass , while tractive effort was improved and this improved heavy lugging capacity on grades , power to construction mass relation of such an engine could no longer compete with engines designed without such dead mass . I have compiled a data table of engine classes here concerned , based on data in literature (in case you might have more precise figures on items , you may want to let me know) . It’s meant to show relations of mass , tractive effort and power output . I’m afraid , you’ll have to click for full size as it’s essential to see it in 1:1 scale or else the font will not be displayed sharply defined ; I'm not sure if it works , if it doesn't I'll find another method (add.: you may press [ctrl] plus run the mouse wheel to enlarge display , not perfect but it helps). As can be seen in line 12 , boilers of Mallets were somewhat less large in relation to engine mass than in rigid frame engines . As boiler design trend went away from searching maximum heating surface by long tubes of small diameters , there is a general decrease of heating surface per ton of engine mass ; still evaporation capacity per ton of engine mass did go up as steaming rates were substantially increased with improved boiler and draughting design . On the other hand , Articulateds provided superior tractive effort – see line 13 – mainly by sheer number of powered wheels ; in the rare case of UP 9000 and Challenger with both engines having twelve coupled wheels , it was largely a matter of larger mass per axle permitted meanwhile and design having specified somewhat stronger cylinder t.e. while the 4-12-2 was said to have been more sure-footed . However , Mallet’s ihp power per ton of locomotive mass was not equivalent to rigid frame types , see line 14 (engine plus tender , since rarely has an engine been seen at work without one) . Line 15 – power to boiler size – would hint somewhat higher specific steam consumption in Mallets , which in fact is a consequence of long steam pipes , however I wouldn’t want to over-rate this item . Line 16 clearly shows power-oriented characteristics of single drive unit types against tractive effort oriented double drive unit types as design progressed . Oh, and while we’re at it – here are some links to you-tube vids to the topic : http://www.youtube.com/watch?v=9alWb5KI5Uo&NR=1 Red headed , erh cab , UP 3985 on road test pulling diesels dynamic braking
Hi folks
Yes, the wheel treads wore circumferentially uneven . That was a consequence of a steam locomotive’s curve inscription with powered axles rigidly in frame and it’s various disturbing motion while running , caused by reciprocating masses (and thus the more so , the less well balanced the engine unit was) . We’re speaking of 1/32 to 1/16 ins between high and low spot in a worn tire , though – nothing to prompt noticeable extra disturbance nor any consequence to track maintenance . For instance , on Decapod engines wheel flanges on the leading coupled axle wore decidedly faster than those of intermediate coupled axles and to a different lateral pattern , too , because first coupled axle was taking a share in guiding the engine in curve – DR Decapod classes were equipped with Krauss-Helmhotz-truck which combined leading Pony truck with lateral motion on first coupled axle so as to level and dampen peak flange forces while fifth coupled axle was laterally moving to run free of flange contact in wider curves or guide itself in sharp curves . Heavier wear on first coupled axle was because it could not inscribe properly in curve but run with flange contact on the outer rail at an angle to rail , thus tread wear was increased over second , fourth and fifth coupled axles .
Because longitudinal oscillation , unbalanced reciprocating masses , all coupled wheels showed circumferentially uneven wear of treads as this action could not go without varying degrees of micro slip . As axle bearings and axle box sliding in pedestals developed play , main drive axle also suffered by rattling under the influence of these unbalanced masses , which was destructive not just to bearings wear but also to tire wear if you think of how that axle changed position 4 times per wheel turn , thereby adopting two counteracting positions not strictly at right angle to longitudinal center line , one forward and one backward stop position within the amount of play .
Since the coupled axles all showed different patterns of motion on track with engine running at speed , overall wear of wheel tires differed and engines tended to get non-identical drive wheel diameters by accumulating mileage and this disturbed proper adhesion , additional to disturbing knocking action by play in bearings and axle boxes , all combining to make engine slip easier .
The valiant Y-6 compound Mallet :
I guess what Big Jim has in mind is grade climbing – there is no doubt Y-6 engines lived up to best standards in very heavy ramp work and did so at relatively economic coal consumption . Yet , as this heavy lugging operation necessarily went along at low speeds , equivalent power output was not as high as with running maximum power at speed , like with an A class 2-6-6-4 at 50 mph . To produce some 7000 – 8000 ihp at 20 mph would have called for multi-unit diesel tractive effort and by default that clearly was beyond limits of any 2 x 8 coupled Articulated – Mallet , Garratt or you name it . As some of the Mallet’s engine mass consisted of unproductive mass inserted just to augment adhesion mass , while tractive effort was improved and this improved heavy lugging capacity on grades , power to construction mass relation of such an engine could no longer compete with engines designed without such dead mass .
I have compiled a data table of engine classes here concerned , based on data in literature (in case you might have more precise figures on items , you may want to let me know) . It’s meant to show relations of mass , tractive effort and power output . I’m afraid , you’ll have to click for full size as it’s essential to see it in 1:1 scale or else the font will not be displayed sharply defined ; I'm not sure if it works , if it doesn't I'll find another method (add.: you may press [ctrl] plus run the mouse wheel to enlarge display , not perfect but it helps). As can be seen in line 12 , boilers of Mallets were somewhat less large in relation to engine mass than in rigid frame engines . As boiler design trend went away from searching maximum heating surface by long tubes of small diameters , there is a general decrease of heating surface per ton of engine mass ; still evaporation capacity per ton of engine mass did go up as steaming rates were substantially increased with improved boiler and draughting design . On the other hand , Articulateds provided superior tractive effort – see line 13 – mainly by sheer number of powered wheels ; in the rare case of UP 9000 and Challenger with both engines having twelve coupled wheels , it was largely a matter of larger mass per axle permitted meanwhile and design having specified somewhat stronger cylinder t.e. while the 4-12-2 was said to have been more sure-footed . However , Mallet’s ihp power per ton of locomotive mass was not equivalent to rigid frame types , see line 14 (engine plus tender , since rarely has an engine been seen at work without one) . Line 15 – power to boiler size – would hint somewhat higher specific steam consumption in Mallets , which in fact is a consequence of long steam pipes , however I wouldn’t want to over-rate this item . Line 16 clearly shows power-oriented characteristics of single drive unit types against tractive effort oriented double drive unit types as design progressed .
Oh, and while we’re at it – here are some links to you-tube vids to the topic :
http://www.youtube.com/watch?v=9alWb5KI5Uo&NR=1
Red headed , erh cab , UP 3985 on road test pulling diesels dynamic braking
from the video : 3985 pulling against dynamic braking with drive sets almost perfectly synchronized
http://www.youtube.com/watch?v=vCaZgOOjNKE&feature=related
UP 3985 after rebuilding , fitted with double Lempor- starting with diesel dyn braking ;
pacing at speed – just for the grand splendor of it / starting with drive sets at about 120 ° phases
from the video : starting with drive sets at some 120 °
Challenger 3985 ready to take the challenges again test run w DDA40X dyn brake diesel – pacing at speed : 1:48 the 4-6-6-4 riding like a Cadillac 3:00 I can see a difference in throw-out of gas/steam mixture 7:16 accelerating w drive sets at right angle – double show with double drive sets
Challenger 3985 ready to take the challenges again test run w DDA40X dyn brake diesel – pacing at speed :
1:48 the 4-6-6-4 riding like a Cadillac
3:00 I can see a difference in throw-out of gas/steam mixture
7:16 accelerating w drive sets at right angle – double show with double drive sets
from the video : starting with drive sets at right angle - four beats per revolution of wheels and a splendid sight
http://www.youtube.com/watch?v=9LsuNWjRaAo&feature=related
combine the sound of cars from this with accelerating Challenger
http://www.youtube.com/watch?v=x8f9VFlNyDQ&feature=related
Big Boy in regular traffic – 2:40 starting out w heavy freight , hear synchronized beats
http://www.youtube.com/watch?v=cl22e1yQ7ZQ&feature=related
amazing : double heading a coal train two little BigBoys have synchronized beats with each other – or so it sounds
http://www.youtube.com/watch?v=QhQMqKl38wU&feature=related
G-scale BigBoy with looong train – 4:00 “slowly accelerating the cars …”
slowly ?? considering the 152 cars train I guess that was a start like on Sunday at the drag strip , synchrocooperised or not !
Regards Juniatha
July 8th :
I deleted the table because the format is too large (1000 px x 1588 px) , automatically resized
to reduced scale the font gets blurred . If you want a clear 1:1 copy.jpg you may write a message to me .
= J =
I’m afraid , you’ll have to click for full size as it’s essential to see it in 1:1 scale or else the font will not be displayed sharply defined ; I'm not sure if it works , if it doesn't I'll find another method
Juniatha,Once again your sense of style is getting in the way of the ease of reading. This time the background of your data table is a big distraction interfering with the ability to read the fine print.
BigJim but the Y6 weighed nearly 140,000 lbs more. Closer to 89,000 lbs. but who's counting.
Closer to 89,000 lbs. but who's counting.
Y6b engine weight was 612,000 lbs. A NYC S1a engine weight was 471,000 lbs. That makes the Y6b 141,000 lbs heavier than the S1a, but both locomotives produced similar peak HP.
BigJim And we've seen how a Y6 could out perform an Allegheny and a Yellowstone.
And we've seen how a Y6 could out perform an Allegheny and a Yellowstone.
How do you define "out perform"? Initial starting tractive effort? Then perhaps you may have a case for the Y6b. Pulling tonnage at 45-55 mph? Then that is a different story. A Y6b would be running out of breath at those speeds, while an Allegheny or Yellowstone class would be right in the heart of their horsepower curves.
A Y6b may have been the most advanced slow service compound articulated ever made, but their boiler output wasn't even close to a Allegheny or Yellowstone. That really isn't a issue, because the N&W used the Y Class within its design parameters and didn't expect it to be something it wasn't.
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