Steam & Excursion > top speed for 4449

This engine will do an honest 105 and a wee bit more. After that we get into Dynamic Augment. Better to slip down to
3 coupled or 2 coupled engine to really curl your toes!
Those Penny atlantics could really burn the rail, but I know of one even faster. (128+)!!

ValvePilot Wrote:
-------------------------------------------------------
> This engine will do an honest 105 and a wee bit
> more. After that we get into Dynamic Augment.
> Better to slip down to
> 3 coupled or 2 coupled engine to really curl your
> toes!
> Those Penny atlantics could really burn the rail,
> but I know of one even faster. (128+)!!

I don't understand your point. Have ever been over 80 MPH on a GS-4, let alone 4449?

Jack, I remember seeing you guys had her at 75 from Fleta-Rosamond back in 84!

Back when Railroad Magazine ran its annual speed tables, the eastbound San Joaquin Daylight was always in there from Fleta to Rosamond. SP had one of their orange speed signs just outside Mojave eastbound that read "70" - the orange ones were just for 52, the eastbound Daylight! This was in the 40s and 50s when they ran GS-4s and MTs double-headed from LA to Bakersfield.
At the same time the Santa Fe's diesel-powered Golden Gates would run over 100 between Bakersfield and Hanford...

Bill Deaver
Tehachapi, CA

I agree with Hotwater.

By your logic, ValvePilot,  the N&W 611 will get into trouble at "wee bit moe than" the popularized 110per.

I have often postulated that any 80" engine will go as fast as any 70" drivered engine, have an easier time of it, and will then go on to reach the same, scary driver RPMs , and thus will be traveling WAY faster, than the top speed of the low drivered engine.
The driver RPMs for the smaller wheels, if matched by the 80" drivered loco, would easily be covering way LESS distance,  ALL at the SAME rotative speed.

So, yes there is a point where the counterweights do begin to lift the drivers..... But, that would easily be over the earlier guess: about 105-per.

Akso, it is WAY easier to properly balance a larger diameter driver than the 70" drivers of the J.  However, the craftsmen at Roanoke certainly knew their stuff.   That whole redesign of the TIMKEN 'Tandem" side rods ( between axles 2&3 ) reveals the the engineering prowess of Roanoke.  The designers at Roanoke KNEW that they HAD to reduce all that extra Timken-weight side rods, bearings, etc...

Timken's Tandem rods added a LOT more reciprocating mass ---- THAT necessitated relatively more massive counterweights.
The whirling counterweights DO actually have the capacity to lift the drivers, as the weights travel the top arc of the drivers.
What's worse is the same terrific forces acting on the rails, as the weights swing through the bottom of the arc.

What Roanoke geniuses DID, was design a simpler approach to reducing the mass needed in the counterweights ( to offset the corresponding larger masses of all those 'extra rods' ,  bushings, races, cages and rollers.  Also, they reduced the length of the crank pins.  The main rod could be physically moved closer to the driver hubs, and the reduced length of the crankpins --- all totaled to reduced reciprocating masses.....thus,  the counterweights could be less massive than those required for the TIMKEN design.

The 'science' of proper amount of counterweighting the drive chassis is almost ALL guess work and experience borne of a vast reservoir of what DIDN'T work.   Trying to make all that whirling mass of 3-D rotating and reciprocating 'scrap iron' a true modern ---mechanical system--- a member of the Seven Wonders of the Steam Loco World, at the middle of the 20th Century.

SO, Lima Loco had a much EASIER task at achieving a good, near perfect counterbalanced regime.
The use of plain bearing siderod components which meant a much lower mass at the crankpins.
You only have 3 components: the Gun-iron bushing pressed into the rod 'eye', the crank 'brass', itself and the bare crankpin (plus the outer retainer and the nut) ----- that''s IT.

• The Daylight's rods are closer to the driver hub, than Timken"s Tandem Rod configuration, AND the lighter weight, clevised, outer side rods are all in the same lateral plane--- connecting drivers number 1 & 4
• Timken's design has all the side rods with only two holes, thus, at the crankpins you have  double the mass of the two rod's bearings hung on the same crank pin.
• The added weights of Timken's design led to the advertising campaign of so-called light weight drive rods.  The added masses of ALL those roller bearing assemblies, NECESSITATED the use of higher strength siderod steels.
• The added reduction of Timken's reciprocating masses was largely brought about by reducing the masses of the crossheads, the use of hollow piston rods( with solid ends) and the use of truly well engineered, light-weight pistons ---ALL lowered the masses to be counter-balanced at the piston 'reverse points' ( at front dead-center and back dead-center).
• Roanoke's guys DID trade axle shifting flexibility, with their revised drive rod scheme --- which made the Js in freight service ( at the end steam----) very RIGID, AND DID NOT TAKE POOR-TRACK, WELL--- when somebody thought it might be good to put the Js on freight trains ----which  led to RASH of many Js spreading the rails and settling the tires neatly onto the cross- ties...of the poorer maintained yard tracks and side tracks, sidings, etc.

So, Lima's Daylights, and all similarly equipped, large diameter engines, which have larger diameter drivers, thus are a  more easily counter-balanced, and using lighter counterweights, possessing less mass., the simpler plain-bearing equipped side, and Main rods, all favor the Daylight being able to EASILY scream into the 120-mph ranges, all the while whirling at lower driver-RPMs., than other low-drivered engines.

 BUT , high-speed passenger engines were soon made obsolete by propeller driven passenger conveyances, government subsidies which built all land facilities, and the traveling public which chose to be herded, like cattle, around passenger pens, while being charged exorbitant prices for today's abuses forcing herd-like passenger cramming....oh well, that's 
"progress"....

So,  like I I've told Ross, you can take any engine as good as the J-class, run her as FAST as you dare, and, in on a parallel track, the Daylight, at the SAME axle RPMs , will EASILY 'stroke on by' the tiny, whirling drivers of the 611.

IMHO...
Wes C.

 



Edited 8 time(s). Last edit at 02/06/16 08:43 by wcamp1472.

Wes, you continually amaze me with all your knowledge.

Not trying to stoke any fires here, but just some simple numbers.   A 70' wheel covers 18.333 feet per revolution, therefore at 110 MPH, a 70" wheel is doing 528 revolutions per minute, or 8.8 revolutions per SECOND.
  
That is a real balancing act, considering all of the reciprocating weights and their different relative motions.

Carrying that one step further, an 80 inch wheel covers 20.95 feet per revolution, which at 528 rpm allows it a speed of 125.7 mph.  

I don't know if 528 is a magic number or not, but a that RPM, you can simply multiply the driver circumference in feet by 60 to get the top speed of the engine.  

Thus the 84" drivers of the Milwaukee and Santa Fe 4-6-4's theoretically could have been good for 134 mph at 528 rpm. 

Finally the rumored speeds of 140 mph for 80" drivered engines would mean that the drivers were actually running at 588 RPM or 9.8 revolutions per second.  

Just some things to think about ......
 

 

Yah but that's not the longevity issue, sure that's a bunch of mass and yes dynamic augmentation
and all that can set in BUT have you ever seen a valve spool big enough to feed say 26" cylinders
out on a table? Consider that mass moving left then instantly moving back right the number of times
required to reach 100 mph? The stresses in the valve gear in handling these loads is pretty incredible.
The pistons at least have some cushion based on the back pressure on a pretty substantial area, the
spools don't. Big steam at speed is pretty amazing when you get down to the nuts and bolts.

Out

There is a potentially apocryphal story about an SP road foreman who was detouring a 4400 over the Santa Fe which had much higher speed limits than the SP and he decided to see how fast his 4400 would go.  As the story goes he went VERY fast, the ATSF dispatchers noticed, and  a letter was sent to SP complaining.

JBWX 

On the other end of the subject, there were small 0-4-0 and 0-6-0'a That rarely ever ran more that ten or 15 mph in the yards. They were all counter balanced too, but at what speed, or RPM was it really necessary for the job they did ?

Posted from Android

Re: Swithchers..

Similarly, the huge N&W's later 'Yx' class engines had drivers comparable to 0-X-0 Swithchers.
With such small diameter drivers, there is very limited room for counter balancing.
For the actual weighting, the steel driver center castings have pockets cast into the voids of the semi-circular shapes that make up the visible 'counter weights.  The mass of the weights is molten lead pored into the voids.  The voids' pockets were then covered with steel plates and securely welded closed.  This gave the designer the flexibility they needed to custom 'adjust' the amount of counterbalance they were striving for.

[ At scrap yards, when the drive wheels were cut-up, the lead counterweight material , in those cavities,
was LEAD POWDER....pounded to dust by the whirling drivers and the constant battering that occurred.].

For such small drivers, Some Y-classes were anecdotally reported as moving along, very well, at over 50-per...

The BEST WERE THE   "A"classes with 3-coupled axles & 100%Timken roller bearings ----
I admire them the greatest... 1238(?) to 1242(?).

I took slides of the 1240, at Shaffer's Crossing Roundhouse, July 1959.  
SO BIG. The only shot I could get was of her front, from outside the stall window.  
Also, back inside, some slides of the 611, cold  & dead,--- a couple of stalls over, and also some Ys, simmering softly in the quite of the roundhouse...as well as a couple of 0-8-0s, under steam, too...

The 'A's.......?
They all got cut up, save for 1218.  
DEEP "Thank yous"  are due to F. Nelson Blount, Bob Claytor, C. Bruce Sterzing, Ross and Edgar Mead, of Steamtown.....for arranging to save the LAST of the "A"s.....

But, again, most of the credit for getting 1218 operational, after leaving Steamtown,  goes to ....drum roll..... SCOTT LINDSAY, Boy Wonder of Big Steam...
( at least he'll always be a 'boy' to me,------ from the HICO days...)

Wes C.



Edited 2 time(s). Last edit at 02/06/16 12:16 by wcamp1472.

Re: elueck, above..

Thanks for the geometry of the Real-Life numbers work....when you actually pace-off the the numbers of the distances, and the revs per second, and four admission and exhaust cycles per second.......
it's astounding the amount of difference is, for the ground speeds were talking.

Thanks for the slide-rule work...

Wes C.

There's a wonderful John Briggs recording of a PRR K4, racing northbound from Matawan, NJ towards South Amboy -( 1955? 56?)----

The roar at the stack goes from sharp blasts , to very fast beats, to a steady ROAR, LIKE A SCREAMING JET, ON A TEST STAND,,,
With the K4,  and its 80" drivers at better than 80-per.... [ 27" inch Pistons, and 200PSI boiler pressure..1918 style...]
That will pin your ears BACK!!!

W.

 

Wes,  
Those are part of the things that most people don't think about when they see a steam locomotive in operation.  So many parts moving in multiple directions, all at the same time, multiple times per second, and all powered by a pressure cooker that basically is a rolling bomb should something go wrong.  Finally all held on a pair of rails by some flanges that are only 1" tall.  
Having said that, I guess that we are very fortunate that any of them operate, anywhere in today's society.  Again, we are very fortunate that we have people who are willing to take the time, and make the effort so that these wonderful machines are maintained the the proper condition to do what they were built to do, especially when the youngest USA made machines are now over 65 years old.

 

Great info,  elueck...

There is also the physics of HOW that train ACTUALLY gets propelled/pulled ---- what is actually taking place, as far as the imaginary 'lever' of the Arm, the Lever and the Weight ----- where the Fulcrum is at the dry rail, the Weight is applied at the axle (driving box) and the Force is applied, to the crank, at the crankpin.  

I haven't figured out how to illustrate the forces, but an imaginary concept/metaphor could be useful.
Imagine that there is an open crack in the frame, just above the subject axle:  at one portion of the stroke (180 deg) the train, dragging on the drawbar, and the piston acting on the frame ---- causes the crack to open-up.

On the other portion of the stroke ( the OTHER 180 deg), the same forces cause the crack to close-up.

So that, when on the 'bottom quarter' (engineer's side) the wheel stays PLANTED, the train is moved by the steam expanding and is pushing the front cylinder head AWAY from the piston ---- naturally, the front cylinder head is dragging the WHOLE train ahead!

Similarly, on the other portion of drive wheel rotation, the wheel-rim stays PLANTED,  and the driver crankpin is pulled by the piston, closing the imaginary 'gap'.  Now, the piston is pulling the train. 

Again, at the top half of the wheel, With  respect to the ground, the piston and crankpin are traveling at virtually double the engine's speed --- across the top half of the crank-circle.

Maybe you can describe in simple terms how the combination of the drivers and the frame contrive to pull the train down the tracks.

I was astounded by the part about about the cylinder head having to pull the whole train..... Now I see why they use SO MANY. cylinder head studs...

My brain got twisted and cramped-up.

Wes C.




 



Edited 1 time(s). Last edit at 02/06/16 12:51 by wcamp1472.

jbwest ----
Please --- just how fast DID that 4400 go?   My curiosity
is killing me!  Thanx for the story!

Wes ---
Thank you very very much for the fascinating info with all
those neat details about how our beloved steam locomotives
actually work.  And thank you very much for pointing out how
incredibly amazing it is that all those heavy and very differently-
shaped parts actually manage to work well together, and rarely
ever fly apaert. 

I have sometimes wondered what a photomicrograph of the
crystalline structures in mvarious moving parts of a steam
locomotive (rods, valve gear, pistons, steam-chest spools, etc.)
would look like at high speed.  That would probably scare the
bejeebers outta most everyone; the  huge stresses and changes
in the structure of the metal would amaze us all.

Yes, how DOES all that mass (rods and pistons and valve gear
manage to reverse direction almost instantly?? The more I learn,
the more amazed and stunned I become that any steam locomotive
can run!  The gigantic amount of energy required to do that successfully,
day i and day out, iis astounding.

Yes, the mind boggles.....  I think I just sprainted my brain!! 



Edited 1 time(s). Last edit at 02/07/16 22:28 by Margaret_SP_fan.

Margaret,

Take a look at the pictures of the new pilot truck wheel sets going under the J #611.

iIt'll put a BIG smile on your face, what those guys have accomplished...

Wes C.

In his book, Life and Times of a Locomotive Engineer, Charles Steffes talks about sneaking the one and only, 4449 up to 100 MPH somewhere between Lancaster and Dennis one night back in the 50s. He said it was stable as a rock.
Remember, ATSF had Automaitc Train Stop (ATS) so they could go over 79 MPH. SP did not.
Scott

MojaveBill Wrote:
-------------------------------------------------------
> Back when Railroad Magazine ran its annual speed
> tables, the eastbound San Joaquin Daylight was
> always in there from Fleta to Rosamond. SP had one
> of their orange speed signs just outside Mojave
> eastbound that read "70" - the orange ones were
> just for 52, the eastbound Daylight! This was in
> the 40s and 50s when they ran GS-4s and MTs
> double-headed from LA to Bakersfield.
> At the same time the Santa Fe's diesel-powered
> Golden Gates would run over 100 between
> Bakersfield and Hanford...

Scott Schifer
Torrance, CA
TinyTrains Website