NKP Berk's Exhaust Beat at Speed

[dabug]

I'm familiar through various video and audio recordings with the peculiar exhaust beat characteristic of Nickel Plate's 2-8-4's at speed: a sound reminiscent of a galloping horse.  However, I have never run across any written documentation explaining this phenomenon.  In my ignorance I assume it may have something to do with cutoff adjustments and/or valve settings as the speed climbs.  I'm sure there are some in this learned forum audience who can enlighten us on this subject.  Thanks!  

[timz]

dabug

I'm sure there are some in this learned forum audience who can enlighten us on this subject.

I doubt it.

 As far as we know the valvesetter's aim is to get the exhausts equal and evenly spaced; an irregularity peculiar to a certain class of engines on a certain RR is unlikely to be explainable by an analysis of any engine dimensions or features-- not now, anyway, and probably not then. Conceivably NKP's rules for valve setting somehow led to that result, and if you knew those rules you could hope to explain it, but even that sounds like a tall order.

[BigJim]

dabug,
Look here for your answer: http://ogaugerr.infopop.cc/eve/forums/a/tpc/f/46660482/m/68610976

[dabug]

Big Jim:

Thanks for the ogaugerr.inforpop.cc link; that helps some in explaining an NKP Berk's peculiar exhaust beat.  Guess one can say the primary "culprit" is the Baker valve gear.  Unfortunately, that prompts another question from my warped, inquiring-railfan mind: did C&O 2-8-4s and PM 2-8-4s - all close cousins to the NKP engines - display the same characteristic?  (I'm pretty sure they were also equipped with Baker value gear.)  Anyone in the audience want to take a crack at that one?  Thanks!

dabug  

[BigJim]

I wonder if there was a difference between the long and short versions of the Baker Valve Gear?

[The Commodore]

Dabug,

  I don't have any technical data but a friend of mine celebrated his 12th Birthday with a 125 mile run in the 765 wearing Southern's colors.  By the way, the railroads out west would have never been built without the "government" granting them the land and credit to build them. The 765 was one incredible engine and the sounds were distinctive.

All the best,

The Commodore

[dabug]

Thanks Big Jim, and to the others who have responded with insights into this complex subject.  I wouldn't know from Adam the differences between long and short versions of the Baker valve gear, or for that matter, that there ever was such a thing.  Even though some of us relics are old enough to remember steam in everyday service, I guess we're not too old to learn something new.     

[selector]

I don't know the answer to the question, and should probably defer to those who point to the peculiarities of the valve gear.....but....I believe the cadence, with the accented exhaust on the one stroke, is due to the fuller compression, and delayed release, of the exhaustable steam as the driver on the one side, whichever it is, has to complete a slightly further rotation to get the valve to open.  I think, therefore, that quartering may have something to do with it.  What else could explain a stronger "explosive" release, with its accompanying enhanced sound, except that there is more pressure to release on the one baring of the exhaust port?

[Idaho Narrow Gauge News]

 This is really fascinating stuff! I have always been a techie, tinkerer and dreamer of mechanical devices so the steam locomotive has alway fascinated me.

 Now: Can someone point us to some mp3s or videos online that highlight these differences in sound for us who were born after the steam age?

 

 {Photo of the Challenger at speed not showing up}

The Challenger was the first time I had ever seen any mainline steam at speed and what a sight! I was suprised though at all the 'clanking' of the rods and valve gear being most of it was equiped with roller bearings.

[BigJim]

I believe the cadence, with the accented exhaust on the one stroke, is due to the fuller compression, and delayed release, of the exhaustable steam as the driver on the one side, whichever it is, has to complete a slightly further rotation to get the valve to open.  I think, therefore, that quartering may have something to do with it.  What else could explain a stronger "explosive" release, with its accompanying enhanced sound, except that there is more pressure to release on the one baring of the exhaust port?

In simpler words, the valve is out of adjustment. Due to how tight the wheels are held on the axles, I've never heard of the drivers being out of quarter.

[Deggesty]

Hmm. I never really had an opportunity to pay attention to the exhaust of an N&W J (they also had Baker valve gear) at speed; I rode behind one from Radford to Bristol and from Bristol to Wytheville, but do not rembember hearing the exhaust. Did anyone who had an opportunity to hear the 611's exhaust at speed when the Southern/NS was running her in excursion service notice anything odd?

Johnny

[selector]

Big Jim, not out of quarter, but that they are quartered.  There would be, as you have pointed out, a possible variation such that one stroke is slightly long, allowing more steam into it(?) and we get the accented bark on the one evacuation.

Here is a youtube video of the J on a grade.  I can detect a slight emphasis on the one "beat".  My BLI K4s with a QSI decoder has a very distinct accented beat which I like a lot, and recall hearing on other live steamers in years past. 

Go ahead, boys, turn up the volume. 

http://www.youtube.com/watch?v=0XYubcZV0Uc

-Crandell

[dabug]

Johnny:

I've had the honor of riding behind 611 as well as chasing her on excursions during the 80s and 90s.  Audio recordings I made of her as well as 'professional' recordings I've heard fail to display an exhaust beat akin to an NKP 2-8-4.  Crandell mentioned 611's accented exhaust beat (one beat of four.)  If you have the opportunity to listen to recordings of different steamers, you can frequently detect that phenomenon with many different steam engines at low speeds.

To open another can of worms, I always considered 611 a disarmingly soft-spoken machine compared to other "noisier" excursion-era steamers such as RDG 2101, C&O 614, and even NKP 765.  Case in point: About 19 miles west of the Ohio state line in Indiana on I-70 is an interchange with Indiana SR1.  Turn north on SR1 and in four miles you'll come to a grade crossing, just east of the town of Hagerstown.  This is the ex-PRR main between Cincinnati and Chicago, now owned by NS, which used this line for their occasional Cincinnati-Muncie steam excursions.  When you look west toward Hagerstown at this single-track crossing, you note the track goes noticeably downgrade before bending left out of sight in the far distance.  Which means trains heading for Cincinnati are coming upgrade at this point.  The track is laid through a slight cut on both sides of the crossing, the road afforded wide shoulders for safe parking, and open viewing in a country setting.  Now, venture back with me to 8/25/84... NKP 765 is storming up this grade with 19 cars, returning to Cincinnati.  Consider this... even after the train had disappeared from view to the east, 765's characteristic "galloping horse" exhaust beat remained audible for several minutes, slowly fading in the distance.  Now fast-forward with me to 9/19/92... this day N&W 611 is stomping up this same grade with 18 cars.  Surprise - no sooner had the train disappeared from view than the exhaust sound of soft-spoken 611 was also gone.  One less car could not make such a dramatic difference in the length of time (or lack thereof) the exhaust sound lingered in the air.  I'm sure steam mechanics could offer leaned explanations on each machine's operating pressures, size and design of exhaust passages, etc. to explain why 611 seemed so "quiet" compared to other engines.  In my ignorance, I like to think 611 was simply so powerful, she didn't sound like she was working hard even when she was.

Dave                   

[Deggesty]

Crandell, thank you for the two videos. They were beautiful. I had never before heard a J working hard for so long. Getting the Pelican underway out of Bristol was absolutely nothing compared to this (and, I do not know how many times I stood at the head end, waiting for the highball so I could watch the departure, complete with cinders). I did detect a little off-beat, but, from what Dave (Dabug) comments, it is nothing when compared with the 765 (which I have never heard). I think that we can all agree that it is not the type of valve gear that causes the beat on the 765. I also do not recall hearing anything odd from the Southern's 4501, 630, and 722 (which I rode from Anniston to Birmingham in December of 1970), or the S&A's 750 when I was riding behind them. To a certain extent, I regret that I moved here before the Southern/NS began operating all the other engines out of Birmingham.

Johnny

[BigJim]

Surprise - no sooner had the train disappeared from view than the exhaust sound of soft-spoken 611 was also gone. 

Then you haven't heard the J on O. Winston Link's "Sounds of Steam Railroading - Vol.1" or on "The Fading Giant Vol.2".

On a quieter note, I have heard 611 start at 24th St. heading for the house and you absolutely couldn't hear it moving!

[dabug]

BigJim: 

BigJim

Then you haven't heard the J on O. Winston Link's "Sounds of Steam Railroading - Vol.1" or on "The Fading Giant Vol.2".

Well, as a matter of fact, I have both those record albums on hand.  And personally, I consider the recording of 603 at Rural Retreat VA on Christmas Eve night, 1957, to not only be a classic, but also the benchmark against which all other rail recordings should be judged.

Nonetheless, it's interesting that those chases involving 765 and 611 at that grade crossing in Indiana allowed the audible demonstration of how "quiet" 611 was as compared to 765 on trains of virtually the same length and tonnage on the same grade.  Kind of rankles the sensitivities a bit since most of us probably think a steam locomotive should not only be BIG and intimidating, but noisy too. 

Dave 

   

 

[BigJim]

I would tend to think that much of the difference will be found in the valve events. Maybe a closer comparison could be had between the 765 and 1218. Dad often mentioned that his favorite loco was the Class A because it would "crack" at the stack.

[dabug]

I've read and heard about an N&W Class A's ability to "crack" at the stack.  Only up close and personal experience I've had with an A was chasing several excursions pulled by 1218.  However, even with passenger consists in excess of 20 cars at times, the flatlands of Ohio didn't offer her much of a chance to "sound" off all that much.  (Was, however, interesting to hear the exhausts of her two engines go in and out of sync, especially at low speeds.)

To open another can of worms... If you readers had the chance to choose between 611 and 1218 in operation, which engine would you pick?  I'd pick 611.  Just can't wrap my mind around 1218 in excursion passenger service.  I know, I know, the A's were built to romp with either time freights or passenger trains when needed.  But 611's classic lines just scream out for a trailing passenger consist.  Besides, I never cared for the N&W hooter whistles used on the A and Y classes.  They may sound "right and proper" in the mountains and hollows of WV, but just never turned me on across the relative flatlands of the Midwest.  However, the haunting, mellow bass notes of the J and K class steamboat whistle sound "right" in any environment to my mind.

Dave 

        

[KCSfan]

BigJim

In simpler words, the valve is out of adjustment. Due to how tight the wheels are held on the axles, I've never heard of the drivers being out of quarter.

Big Jim,

I totally agree. Any steam locomotive whose valve gear was out of quarter would have an irregular exhaust cadence. Ideally there should be a power snd exhaust stroke of the cylinders every 90 degres of wheel rotation. If the valve gear is not precisely adjusted to obtain this you will get an exhaust that sounds like chuff, chuff, chuff-chuff. I doubt this was unique to the NKP Berks any more that to any other engine whether it had Baker, Walscherts or even slide valving.

Mark

[selector]

And yet, I'll disagree, Dave.  First, I am a big fan of articulated engines, so I am already biased in my choice between the two.  But I also like the hooter.  I could do without the seemingly incessant sounding that the engineer back in the 80's seemed to like to play it...it was often played too much for no apparent reason other than to please fans. 

Here is a video from youtube with plenty of the barking stack-talk that you like.  The first two and a bit minutes is runpast and later a bit disjointed, but near 2.5 minutes a sequence begins with 1218 stalled on Christiansburg Hill. It tries three times and fails to get underway.  All you can hear is the stack barking and the engines slipping because the train is behind a rock outcropping on the grade at a curve.  When it gets underway finally, it is a sight to behold as it rounds the corner.

You won't be disappointed.

http://www.youtube.com/watch?v=so7-Fu2psjc

[feltonhill]

 This is a very interesting video, particularly the C-burg hill start.  The first three attempts which failed sounded much different than the last, sucessful start.  It sounds as if the engineer (Bob Claytor??) used too much throttle too soon, which produced the typical loud cracking sound an A was famous for, but was too much for the poor rail condiions.  Plus, joint control of two individual engine sets probably  produces a whole new set of challenges for the engineer  The fourth attempt produced a much softer initial exhaust sound due to less throttle. The engineer seemed to let 1218 walk away with the train for awhile before getting into it as 1218 passed the recording location.  Talking to others about this seems to confirm the notion that starting an A under adverse rail conditions was best done with the minimum amount of throttle necessary to get the train moving.  After the entire train was in motion at about 5 mph or so, it was OK to widen out.

 Great way to start my Sunday morning.  Nothing sounded like an A, especially in the first runby.   Thanks for the link.

[KCSfan]

feltonhill

 This is a very interesting video, particularly the C-burg hill start.  The first three attempts which failed sounded much different than the last, sucessful start.  It sounds as if the engineer (Bob Claytor??) used too much throttle too soon, which produced the typical loud cracking sound an A was famous for, but was too much for the poor rail condiions.  Plus, joint control of two individual engine sets probably  produces a whole new set of challenges for the engineer  The fourth attempt produced a much softer initial exhaust sound due to less throttle. The engineer seemed to let 1218 walk away with the train for awhile before getting into it as 1218 passed the recording location.  Talking to others about this seems to confirm the notion that starting an A under adverse rail conditions was best done with the minimum amount of throttle necessary to get the train moving.  After the entire train was in motion at about 5 mph or so, it was OK to widen out.

 Great way to start my Sunday morning.  Nothing sounded like an A, especially in the first runby.   Thanks for the link.

I believe the A's had two sets of sanders and would almost guess one was not working or maybe out of sand. I would expect an A could walk away with no trouble at all with just a few passenger cars even on a grade with wet rail.

Mark

[feltonhill]

 Couple of things to keep in mind.  The train was 21 cars plus an A-tank, probably in the neighborhood of 1,500 tons, not too shabby.  The start was made near Arthur, where the curvature is almost constant at 5 to 6 degrees, and the grade is 1.32%.  1218 was starting on a curve, which means that the front engine was off-center (in this case to the left).  This will upset the weight distribution somewhat compared to starting on tangent track.  So there were several less-than-ideal factors to consider.  The first start clearly shows that 1218 could have walked away with the train because for about 2-3 seconds acceleration was very noticeable.  It sounds to me as if one engine lost its footing but with only one throttle, you have to shut the whole works off until the one set recovers.  The fourth successful start showed much less acceleration initially, but both engines held the rail. The engineer was using enough throttle to get the train under way, but not overdoing it.  You can hear how the two engines move in and out of step until they finally get in step and stay there as 1218 passes the camera.

[Deggesty]

selector

And yet, I'll disagree, Dave.  First, I am a big fan of articulated engines, so I am already biased in my choice between the two.  But I also like the hooter.  I could do without the seemingly incessant sounding that the engineer back in the 80's seemed to like to play it...it was often played too much for no apparent reason other than to please fans. 

Here is a video from youtube with plenty of the barking stack-talk that you like.  The first two and a bit minutes is runpast and later a bit disjointed, but near 2.5 minutes a sequence begins with 1218 stalled on Christiansburg Hill. It tries three times and fails to get underway.  All you can hear is the stack barking and the engines slipping because the train is behind a rock outcropping on the grade at a curve.  When it gets underway finally, it is a sight to behold as it rounds the corner.

You won't be disappointed.

http://www.youtube.com/watch?v=so7-Fu2psjc

selector

I am not disappointed. I never had an opportunity to se, much less hear, an A, and I was glad to see and hear this example of one in service. I forwarded the link, and the link to the J performance to my wife, and she was glad to see and hear both locomotives in operation.

The first time I heard the A's whistle, it seemed raucous to me, but I did become somewhat accustomed to it. I do prefer the sound of the J's whistle (and the 4501's whistle, also).  The A's whistle is not as bad as the horns on the Georgia's diesels I heard, all too often, when I lived in Decatur, Ga.

A question: how is that the two engines of a simple articulated locomotive work their way back into synchronization when they start out of sync?

Johnny

Johnny

And yet, I'll disagree, Dave.  First, I am a big fan of articulated engines, so I am already biased in my choice between the two.  But I also like the hooter.  I could do without the seemingly incessant sounding that the engineer back in the 80's seemed to like to play it...it was often played too much for no apparent reason other than to please fans. 

Here is a video from youtube with plenty of the barking stack-talk that you like.  The first two and a bit minutes is runpast and later a bit disjointed, but near 2.5 minutes a sequence begins with 1218 stalled on Christiansburg Hill. It tries three times and fails to get underway.  All you can hear is the stack barking and the engines slipping because the train is behind a rock outcropping on the grade at a curve.  When it gets underway finally, it is a sight to behold as it rounds the corner.

You won't be disappointed.

http://www.youtube.com/watch?v=so7-Fu2psjc

[selector]

Johnny, here you have me treading water and unable to touch the bottom.  I have no idea except to guess that it has something to do with timing and pulse synchronization that is a natural physical phenomenon, a gentle locking mechanism that doesn't necessarily retain the engines in synch when the adhesion under one of them is insufficient to allow it...that engine will begin to creep out of synch with each steam admittance to the cylinder and subsequent expansion.  I think the machines are sufficiently complex that no one factor is sufficient to cause the effects we see except the cases that are gross in nature and very obvious.

I am pleased that you enjoyed the videos.  They are a good substitute on a cold winter's night when the engine's themselves haven't run in many years.   Just like a good stiff tonic.

-Crandell