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Date: 05/24/23 11:06
4-8-4's and High Speed Running
Author: ApproachCircuit

Of course they were very good at that. Overall the best power for heavier trains. But there is a limit to huge large steam engines. At a certain point , very high
speeds with Northerns reached a practical limit. Dynamic Augment comes into play. At  a certain point things start working against you. All that repicrocating mass
starts fighting back. Thats why 4 and 6 coupled steamers had a slight speed advantage. I think most Northern's had a limit of maybe 115 mph. The SP GS-4s from
Lima had a service speed of 105 mph. Any they were very fine motive power with a stout 5500 HP at the  drawbar. If you want to ride in the cab of a 4-8-4 in the
vicinity of 115 mph be my guest!  Now a Pennsy atlantic E-6 would be a thrill as with a few others; some 4-6-4's too.



Date: 05/24/23 11:22
Re: 4-8-4's and High Speed Running
Author: Txhighballer

ApproachCircuit Wrote:
-------------------------------------------------------
> Of course they were very good at that. Overall the
> best power for heavier trains. But there is a
> limit to huge large steam engines. At a certain
> point , very high
> speeds with Northerns reached a practical limit.
> Dynamic Augment comes into play. At  a certain
> point things start working against you. All that
> repicrocating mass
> starts fighting back. Thats why 4 and 6 coupled
> steamers had a slight speed advantage. I think
> most Northern's had a limit of maybe 115 mph. The
> SP GS-4s from
> Lima had a service speed of 105 mph. Any they were
> very fine motive power with a stout 5500 HP at the
>  drawbar. If you want to ride in the cab of a
> 4-8-4 in the
> vicinity of 115 mph be my guest!  Now a Pennsy
> atlantic E-6 would be a thrill as with a few
> others; some 4-6-4's too.

My great uncle, who fired 2900s' saw over 120 on the speedometer more than once.



Date: 05/24/23 17:18
Re: 4-8-4's and High Speed Running
Author: coach

A STSF 2900 roaring by at over 120 mph---just imagine that!  I wish I could see that in person.



Date: 05/24/23 18:28
Re: 4-8-4's and High Speed Running
Author: callum_out

Considering the size of the train it was dragging at that speed, the horsepower number could be truly considerable.

Out 



Date: 05/25/23 05:50
Re: 4-8-4's and High Speed Running
Author: gbmott

> ApproachCircuit Wrote:
>
> My great uncle, who fired 2900s' saw over 120 on
> the speedometer more than once.

I heard similar stories about 2900's from a retired hogger who ran Amarillo/Clovis.  He liked nothing better than a 2900 with a reefer block.
Gordon



Edited 1 time(s). Last edit at 05/25/23 05:52 by gbmott.



Date: 05/25/23 07:02
Re: 4-8-4's and High Speed Running
Author: jdw3460

I read a book once, written by a Franklin mechanical engineer who had designed,installed, and tested a Franklin rotary cam poppet valve system on Santa Fe's 3752, one of the pre-war northerns that was being overhauled.  Santa Fe was testing the system for possible application to other steam engines.. Of course, by the time it was all done, diesels were lurking in the wings.  The book had the story of 3752 being tested with the Santa Fe's dynomometer car on the "Fast mail and express" No. 7 from Kansas City to La Junta.  That was a very heavy weight train with only two stops on this run.  The account of the test indicated that somewhere in the vicinity of Syracuse, KS the train was hitting 106 mph and the performance was a considerable improvement over their standard 4-8-4's.  I don't remember the horsepower numbers,etc. but the speed was indicated as the highest achieved by a Santa Fe 4-8-4.  The 2900's built by Baldwin during the war were all heavier due to the unavailability of lighter weight steel.  Otherwise, I think they were the same.............roller bearings, etc. The book also mentioned that the day after this test run, the Santa Fe rulebook changed, requiring all locomotives without ATS (automatic train stop) installed were limited to 90 mph.  So 3752 didn't set any speed records after that.  I think it spent most of its days in freight service.  The Santa Fe 3460 class Hudsons were faster but handled less tonnage.  One hogger I knew mentioned running an E-4 diesel double headed behind a 3460 class Hudson on a troop train between Newton and Emporia, KS and reaching 110 mph.  He said he was sweating a little because the E-4 had a governor on it that cut it out at 112.  And he was laughing at the fact that the Hudson's water tank lid had flown open and the diesel was getting its windshield washed.  Those were the days.



Edited 1 time(s). Last edit at 05/25/23 07:43 by jdw3460.




Date: 05/25/23 11:13
Re: 4-8-4's and High Speed Running
Author: SGillings

Just curious, where does the 5500 drawbar horsepower for a GS-4 come from?  I found online that someone said that the Santa Fe 2900s had drawbar horsepower of 4450 (04/05/05 TO).  I thought that the 2900s were more powerful than a GS-4.  Also, NYC Niagara 6023 was tested and the maximum drawbar horsepower was 5070 (site - steamlocomotive.com) and I thought that they were the most powerful 4-8-4s.

Steve



Date: 05/25/23 12:06
Re: 4-8-4's and High Speed Running
Author: callum_out

4450 for a 2900 would seem to be low, their boiler wasn't much different than the 5020 class and they were over 5000 hp.

Out 



Date: 05/25/23 13:22
Re: 4-8-4's and High Speed Running
Author: PHall

GS4's had a trailing truck booster, the 2900's didn't.



Date: 05/25/23 13:38
Re: 4-8-4's and High Speed Running
Author: timz

> Just curious, where does the 5500 drawbar
> horsepower for a GS-4 come from?

It doesn't.



Date: 05/26/23 03:56
Re: 4-8-4's and High Speed Running
Author: feltonhill

I believe you'll find that the 5500 "horsepower" figure for the GS4 is Indicated HP, not DrawbarHP.  Also, the boiler on the later series of ATSF 2-10-4s (5011 clas??) was larger than the 2900 class 4-8-4s.  Something else to consider is that the 3776 class 4-8-4's had a problem in the steam circuit which restricted their DBHP output at high steam flow rates.  This was noted in a test report by the railroad.  If the 2900 class designers didn't correct that problem. they would also be limited to a rather low 4500 DBHP, considering the size of the locomotives.



Date: 05/26/23 07:07
Re: 4-8-4's and High Speed Running
Author: ApproachCircuit

A lot of BS came from the "Old Timers too! Just like today!
BS gets amplified over the years and some people want to believe what they hear!



Date: 05/26/23 09:48
Re: High Speed Running
Author: timz

Very true.



Date: 05/26/23 15:58
Re: High Speed Running
Author: Oldtyme

Most powerful Northerns were the NYC Niagaras built by Alco. 



Date: 05/26/23 16:04
Re: High Speed Running
Author: HotWater

Oldtyme Wrote:
-------------------------------------------------------
> Most powerful Northerns were the NYC Niagaras
> built by Alco. 

Is that just your opinion, or do you have technical facts to back that statement up?



Date: 05/26/23 20:29
Re: 4-8-4's and High Speed Running
Author: Anachronism24

Hello, I'm a long time lurker on the site. I remember reading that all 3 of Santa Fe super power engines built in 1938 (the 3460s,3765s,5001s) all suffered from excessive pressure drops at speed. Lloyd Stagner said that the 1944 built 5011s never had that issue due to being built with larger pipes leading to the cyclinders and larger diameter dry steam pipes. I believe the 3776s and the 2900s both had this issue corrected but I've never officially read that anywhere. I assume they did, because they shared every other improvement the 5011s had over the 5001s and Santa Fe built all 3 of the super power engines to have interchangeable parts. For what's it's worth the 2900s we're tested at around 4600dbhp compared to the 4550 of the 3675s. Not to mention the 3776s and 2900s were generally assigned to the heavier and faster passenger trains while all 11 3765s were placed in freight service in 1946. The Santa Fe further improved the 3776s, 2900s and 5011s by given them 105sqft of security circulators in the firebox and giving the 4-8-4 classes lightweight roller bearing rods and a stack extension that may have further increased horsepower.



Date: 05/27/23 08:50
Re: High Speed Running
Author: Oldtyme

HotWater Wrote:
-------------------------------------------------------
> Oldtyme Wrote:
> --------------------------------------------------
> -----
> > Most powerful Northerns were the NYC Niagaras
> > built by Alco. 
>
> Is that just your opinion, or do you have
> technical facts to back that statement up?

I have the technical facts...do you?



Date: 05/27/23 09:13
Re: High Speed Running
Author: HotWater

Oldtyme Wrote:
-------------------------------------------------------
> HotWater Wrote:
> --------------------------------------------------
> -----
> > Oldtyme Wrote:
> >
> --------------------------------------------------
>
> > -----
> > > Most powerful Northerns were the NYC Niagaras
> > > built by Alco. 
> >
> > Is that just your opinion, or do you have
> > technical facts to back that statement up?
>
> I have the technical facts...do you?

No! So why don't you post them, so that we can all see that the NYC 6000 class locomotives were more powerful than the N&W J Class and/or the Santa Fe 2900 Class Northerns.



Date: 05/27/23 10:30
Re: 4-8-4's and High Speed Running
Author: superheat

I think I read a few years back that a certain UP engineer who was retiring decided to have his way with the 844 and "open the throttle".  Was this a true story and, if so, what was its top speed?



Date: 05/27/23 10:57
Re: High Speed Running
Author: Auburnrail

Going back to the original issue of "dynamic augment," can
anyone give me a simple explanation of why internal combustion
engines with counter weighted crankshafts do not seem to be limited
by this, regardless of displacement?
A genuine question, please no flaming.

George Andrassy 



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