Re: New Broadway Limited UP 4-12-2


MDelvec952
 


The 4-12-2s used a Gresley motion to move the valves in the middle cylinder, and a Walschearts motion on the outside cylinders, which were quartered. Gresley connected the piston valves on the outside with a horizontal rod that was fixed about a third of the way across. On the other third was attached a rod that moved the piston-valve on the middle cylinder. As the outside valves were hooked up at speed, that reduction in stroke was automatically transferred to the middle cylinder. Your drawings that show the drivers were quartered makes sense as the recordings I've heard don't suggest and even exhaust beat. The best imitation of the sound from the old timers I've met from that era said that the sound was similar to: "a-washin'-a-sewin'-a-washin'-a-sewin'-a-washin'-a-sewin'-a-washin'-a-sewin'-a-washin'-a-sewin," and universally the ear-witnesses recalled that three-cylinder engines sounded like they were going faster than they were. That cadence agrees with your middle-cylinder fatter exhaust finding. There was an era when designers added the third cylinder as a way to increase tractive effort and horsepower on a given weight-on-drivers, which reduced the need to add locomotives and crews for a given-tonnage train.

 In the United States, the three-cylinder era was for the most part short lived, and many railroads removed the middle cylinder. UP's 4-12-2s were an exception, as were Alton & Southern three-cylinder 0-8-0s.

As for running prototypes, there are three-cylinder Gresley engines alive and well in England, and the brand new A4 4-6-2 locomotive the Brits built from drawings is a three-cylinder Gresley engine. In the 1970s one of the Gesley 4-6-2s, The Flying Scotsman, toured the U.S. fitted with an American Janney coupler and other devices to meet the FRA requirements. These fantripping 4-6-2s won't put on a freight-hauling performance for the purpose of recording, but they do give a sense of the personality of a Gresley motion.

Of the three-cylinder survivors in the U.S., the Franklin Institute in Philadelphia has Baldwin 60,000, a three-cylinder 4-10-2 that uses a double-walschearts, and that locomotive rolls back and forth within the museum. What's unfortunate is that the side with the two cranks is against the wall so it can't be easily seen by the public.

Those UP 4-12-2s were ponderous machines, and in the talks I've had with some of the veteran steam shooters in the East, they all regreted driving past the UP 9000s on trips west to catch the narrow gauge and short line steam that was about to end any day. They all lamented that the narrow gauge they were trying to preserve on film survived, and the main line stuff they ignored is what disappeared first. I've asked them all why did they didn't shoot more freight cars in the steam era.

I can't wait to hear the models.

                 ....Mike Del Vecchio



-----Original Message-----
From: orthsj@... [STMFC]
To: Classic UP
Cc: STMFC
Sent: Sat, Jan 17, 2015 2:38 am
Subject: Re: [Classic_UP] RE: [STMFC] New Broadway Limited UP 4-12-2

 
Gents....

This will be argued far beyond any of our lifetimes, and no matter what sound was picked, *someone* will complain and say its not correct.  There are no running prototypes, so we all have to go on what someone said, what we can analyze from drawings, or analyze from existing recordings.  There is no winning this debate.

The outside cylinder main rods are quartered 90 degrees apart.  I have the drawing for the main drivers, 954CA28251, and the axle keyways are 90 degrees apart.  The center cylinder is aligned with the axle keyway, making it 45 degrees off one of the outside main rods (not sure if it was right or left).  I have the #2 axle and crank drawing, and the #2 driver drawing, which I just looked at again to make sure.  In "The Union Pacific Type, Vol 1", Kratville & Bush, an Alco graph is presented in the first chapter showing evenly spaced power pulses to the drivers, which points to Alco designing the locomotives to have 6 evenly spaced power pulses per revolution.  Between the unevenly spaced crank pins, tilted up center cylinder, shorter stroke, larger bore, and Gresley valve gear they somehow made that happen.  The evenly spaced power pulses was one of Alco's big selling points, which are quoted in Kratville & Bush.  When the valve gear and crank pins and rods got worn, the timing suffered badly.  That is also discussed in the book noted above.  Anyway....

I recommended that the chuffs be timed evenly on the model.  This was based on an time-amplitude analysis that I did on all of the recordings we could get.  The Fogg, Ragsdale and Whyte recordings have been digitized, so doing an analysis was as simple as installing a spectrum analyzer on my computer and analyzing the files.  When I looked at the time-amplitude of the sound, the chuffs were very clearly evenly spaced.  I analyzed multiple 10 second segments (limit of the analysis program) on multiple recordings with the locomotives running at different speeds.

What I did find was that every 3rd chuff had its energy spread across a wider time period.  Probably 1.5 times as wide as the other two chuffs.  Its peak amplitude was also higher.  I suspect that is what makes that chuff sound "out of time", ie, it starts sooner and ends later.  But, it is very clear that the center of the sound is evenly spaced with the other two chuffs.

I, along with several other people (John Bush, Sandy, and others) suspect the difference in sound is due to the differing exhaust path lengths between the cylinders.  The left cylinder has a normal, straight shot to the nozzle.  The center cylinder has a very short path to the nozzle.  The right cylinder exhaust path has to go up and over the center cylinder's valve, so its path is longer and curved.

The BLI sound developer made every 3rd chuff longer and louder, with all chuffs evenly spaced, like the digitized recordings.  Those recordings are the best evidence available, and they are what was used for a reference.

The whistle came from the ex-UP 2-8-0 running in Alamosa, CO.  That whistle is a Star Brass Co 5-chime from a UP 2-10-2, which is what was used on the 4-12-2.  The bell was kind of taken from the Fogg recording, but if you listen to the recording, there's a ton of warble due to the tape recorder having some tape speed issues.  So, it was just a basis for the bell.

So, if you don't like the sound, blame me.  I expected to get plenty of criticism on this.  But, please be aware that BLI wanted to get it right.  They were very genuine in their desire to have it correct.

Steve Orth





Hi Ben,
 
               BLI had their 4-12-2 on display at Prototype Rails in Cocoa Beach, FL.  Since I have been eagerly awaiting these (I have 3 on order), I was very pleased to see it.
 
               The model looked excellent to my eyes (and without any handy photos, etc. to compare it against).
 
               Unfortunately, BLI did not have a test track.  However, the next table to their left was Intermountain Railway Company, and on their right was Atlas, both of whom had tracks.  I decided NOT to ask IMRC if we could use their test track, since IMRC also makes steam engines in HO.  The Atlas rep was happy to allow us to use theirs.  I threatened to post a photo of the 4-12-2 on the Atlas display, so as to start a rumor…
 
               In any case, the engine sounded very good.  It definitely has an off-beat chuff.  My ears are not calibrated, but for my little demo, we also had Steve Orth (who did much of the research for this model), Sandy McCullough, Mike Brock, Marty Magregian, Terry Kolenc, and Frank Peacock.  These esteemed UP experts deemed the sound “very good” and that’s sufficient endorsement for me!  At slow speed, the sound was very well synchronized to the driver rotation.   I also grabbed ahold of the engine, and it seems to have some pulling power.
 
               As I mentioned, I’ve been waiting quite a while for this model to be released.  BLI said that the “soldering was finished” [it’s a brass boiler], and they expect to have them in the spring of 2015.
 
Regards,
 
-Jeff
 
 
 
 
From: STMFC@... [mailto:STMFC@...]
Sent: Friday, January 16, 2015 4:18 PM
To: STMFC@...
Subject: [STMFC] New Broadway Limited UP 4-12-2
 
 
I just saw Broadway's video showing their new UP 4-12-2 model.  It looks beautiful and I hope they sell a lot of them.  They also say they have it set up for three cylinder sound.  The video does show the locomotive in slow enough motion that you can count 6 exhaust beats per revolution.

However, and there is always a however, the six chuffs per revolution in the part where you can count them are equally spaced as if the drivers and the center cylinder are equally "hexed"  when all of the UP 4-10-2's and 4-12-2's and the SP 4-10-2's were actually quartered like their 2 cylinder cousins with the third cylinder timed at an angle in between two quartered power strokes.  Check a copy of "Three Barrels of Steam" for drawings indicating the proper angle. 

Old timers that operated these engines said they sounded like they were stuttering as they went down the track and the ride took a little getting used to because the power strokes were not at an even pace.

I hope I'm wrong about this, but getting the chuffs synced correctly is very important to me.  I hope someone can view these models in persons and report back about this, especially if I am wrong.

Ben Heinley
Denver, Colorado



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