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Steam & Excursion > What was the most powerful 4-8-4?


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Date: 02/18/21 20:55
What was the most powerful 4-8-4?
Author: steam290

I’ve heard it was the J, but I also recently read it was the Niagara. What was the most powerful 4-8-4 in terms of reactive effort?



Edited 1 time(s). Last edit at 02/18/21 21:00 by steam290.



Date: 02/18/21 21:17
Re: What was the most powerful 4-8-4?
Author: Dreamer




Date: 02/18/21 21:29
Re: What was the most powerful 4-8-4?
Author: MacBeau

From Steam's Finest Hour, Kalmbach 1959.

N&W J
73,000 lbs. TE

AT&SF 2900 class
66,000 lbs. TE

NYC S-1a Niagara
62,500 lbs. TE

DL&W Q-3 Pocono
71,600 lbs. TE

—Mac



Date: 02/18/21 21:49
Re: What was the most powerful 4-8-4?
Author: weather

I realize that is starting T.E.  but the #4449 with a booster i believe is 78,000 T.E. Wes or Jack can chime in here and correct of comment.



Date: 02/18/21 21:57
Re: What was the most powerful 4-8-4?
Author: tehachapi-dave

Based on tractive effort, I believe the N&W J Class wins out with 80,000 lbs of TE for 4-8-4 locomotives as built.  Although I'm not sure how much some of the ATSF engines made after they went through rebuilds post-war, it may be higher.

Tehachapi-TJ Over & Out



Edited 1 time(s). Last edit at 02/18/21 21:59 by tehachapi-dave.



Date: 02/19/21 03:27
Re: What was the most powerful 4-8-4?
Author: wcamp1472

Powerful?

'Powerful' refers to the rate at which "work" is performed.
It is a time-based parameter.  Tractive force is strictly pulling effort at a stalled, 
stationary state. Tractive effort is a fictional calculation, based on piston diameters.

From the wwweb:
"Horsepower refers to the power an engine produces. It's calculated
through the power needed to move 550 pounds one foot in one second
or by the power needs to move 33,000 pounds one foot in one minute."
( " move" means LIFTING, James Watt's definition).

When starting, what are the relative positions of the driver cranks?
In the numbers used in the calculations, is one piston at a dead-center?  
( if so, that piston's rotative force is ZERO)
Or, are all contributing to the rotative force?

How about engines with more than two cylinders

My guess that the most powerful candidates were the ATSF 2900s , and a close 
follow-up would be the NYC 6000s.

Starting Tractive effort is only a mathematical calculation based on standardized assumptions,
and hypothetical equations.
Primary among those published assumptions is steel wheels, on dry, steel rail.
What happens in real-life when starting on dry, sanded rail, all drive wheels 'on sand'?
What's that Tractive Effort number?

I've seen real-life situations where sand added to the rail made ALL the difference when under 
a heavy starting strain....between spinning wildly ( "steel wheels on steel rail " scenario)
and actually climbing the grade, with all safeties lifted....

I'd estimated a 12% to 15% increase in shear pulling capacity over the publishd ratings,
of steel wheels on dry, steel rail.

W.

( Add: WM class J-1,  4-8-4 , 70, 591 TE)



Edited 9 time(s). Last edit at 02/19/21 04:10 by wcamp1472.



Date: 02/19/21 05:48
Re: What was the most powerful 4-8-4?
Author: choodude

At what speed?

Brian



Date: 02/19/21 06:05
Re: What was the most powerful 4-8-4?
Author: randgust

At some point in the distant past TRAINS ran an article called "Was there ever a super 4-8-4?" - I think it was Robert Massena? (doing this from memory) and literally walked through everything including valves, fuel consumption, horsepower, TE.

It won't put debates like this to rest, but it really cuts to the heart about the myriad of features that could be applied, and were.

Everybody will stand up for their own favorite, I'm just feeling privileged that I got to ride behind 611 when Claytor was at the throttle (pre-Dismal Swamp) and the ability of the loco to accelerate an 18 car train from a 25mph slow order back up to 70 and push you back in the seat while doing it was not to be forgotten.   Amazing machine.



Date: 02/19/21 06:31
Re: What was the most powerful 4-8-4?
Author: Arved

MacBeau Wrote:
-------------------------------------------------------
> From Steam's Finest Hour, Kalmbach 1959.
>
> N&W J
> 73,000 lbs. TE
>
> AT&SF 2900 class
> 66,000 lbs. TE
>
> NYC S-1a Niagara
> 62,500 lbs. TE
>
> DL&W Q-3 Pocono
> 71,600 lbs. TE
>
> —Mac

According to this article (link), tractive effort of the AT&SF 3751 class is 79,968 lbs, but as stated above, let's not confuse power with grunt.

Wikipedia lists the Southern Pacific GS-4 as having 64,800 lbs. tractive effort without booster, and 78,650 with.

Respectfully submtted,
- Arved

Arved Grass
Fleming Island, FL
Arved Grass



Date: 02/19/21 06:31
Re: What was the most powerful 4-8-4?
Author: holiwood

I wonder if we will ever hear about the data collected on 611 a few years ago.   



Date: 02/19/21 06:40
Re: What was the most powerful 4-8-4?
Author: Frisco1522

Including booster, Frisco 4500 4-8-4s @8MPH was listed at 80,800.



Date: 02/19/21 07:01
Re: What was the most powerful 4-8-4?
Author: wabash2800

This is a fun comparison but looking at the tables, it made me realize how big of a monster that Santa Fe 2900 under restoration in New Mexico is, both in size and tractive effort. Holy Moly! Looking at the length and height of that loco, including the large drivers alone is inspiring.

A little off topic: I once had a conversation with a railfan that thinks he knows a lot about steam. He referred to the NKP Berks as baby 4-8-2s backwards. I'm sure many would disagree with that being a fair comparison. LOL He also has run-ins with real railroaders, when he tells them they are wrong about every historical fact, even their own jobs they retired from.

Victor A. Baird
http://www.erstwhilepublications.com



Edited 3 time(s). Last edit at 02/19/21 07:14 by wabash2800.



Date: 02/19/21 07:17
Re: What was the most powerful 4-8-4?
Author: wcamp1472

Which 4-8-2s had near 100 sq.ft. grate areas?
Baby 4-8-2s?
 I don't think so!

W.



Date: 02/19/21 08:05
Re: most powerful 4-8-4?
Author: timz

If calculated TE is the criterion, then the
300-psi J is it.

FWIW, calculated TE of IC's 4-8-2 was higher.



Date: 02/19/21 09:39
Re: most powerful 4-8-4?
Author: Bob3985

Lionel solved this situation with "Magnatraction."

Bob Krieger
Cheyenne, WY



Date: 02/19/21 09:43
Re: most powerful 4-8-4?
Author: Trainhand

Where did ACL 1800's fit in with these?



Date: 02/19/21 10:20
Re: What was the most powerful 4-8-4?
Author: Wolfman

Hope that monster in New Mexico moves this year !



Date: 02/19/21 10:30
Re: most powerful 4-8-4?
Author: raytc1944

Bob Krieger,

  loved your reply.  I nearly fell off my seat!



Date: 02/19/21 11:14
Re: most powerful 4-8-4?
Author: MaryMcPherson

timz Wrote:
-------------------------------------------------------
> FWIW, calculated TE of IC's 4-8-2 was higher.

My fellow IC folks might disown me for this, but IC used a slightly different figure for calculating its locomotive's tractive effort.  This inflated the figures compared to other railroad's figures.  Calculating these 4-8-4's using the IC method might result in the IC's engines not looking quite as impressive.

For the life of me I can't remember exactly what the jiggery pokery was in the I.C. figures, but it was in assumed power loss in delivering steam from the boiler to the piston (i.e. calculating 10% rather than 15% or something along those lines).

Mary McPherson
Dongola, IL
Diverging Clear Productions



Date: 02/19/21 11:24
Re: most powerful 4-8-4?
Author: patd3985

Bob3985 Wrote:
-------------------------------------------------------
> Lionel solved this situation with "Magnatraction."

Good one Bob! But let's not forget that American Flyer had the "Mor Pul" system



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