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 Post subject: Re: Was Superpower Oversold?
PostPosted: Mon Jun 27, 2022 5:10 pm 

Joined: Sun Aug 22, 2004 11:54 pm
Posts: 2367
Steamguy73 wrote:
Adding onto the point about the I-2’s, notice how there’s no data past 40 mph for 1111, or the 2-8-0, which isn’t the case for either the Potomac or the challenger (strong point in favor of super power).. Also, this data was in 1947, meaning the Potomacs at this point weren’t even a year old, so their data might not be as accurate as any of the other 3 classes.



I'll have to go back and reread the report, because I don't remember if there was some mention of why the curves for the older engines aren't continued beyond 40mph. Did they not attempt it or where those engines timetable/test limited to 40 or did they just plot what was necessary to show the obvious?

As I look at those curses with HP (P) as a function of speed; P=f(x), it's clear that the power output is more bent back toward a vertical drop the more you are going past the peak; i.e the second derivative is negative. The faster you go, the less power you have to accelerate; so maybe the trains they ran simply made operation above 40 impossible.


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 Post subject: Re: Was Superpower Oversold?
PostPosted: Mon Jun 27, 2022 11:22 pm 

Joined: Fri Dec 22, 2017 6:47 pm
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Location: Philadelphia, PA
I'm not sure anybody wanted to ride one of those 2-10-0's above 40 mph.

RDG and WM pooled between Hagerstown and Rutherford and there are letters from RDG to WM complaining of the track damage caused by the 2-10-0's, There was also a number of letters from WM to RDG complaining of the track damage caused by the RDG 2-10-2's (the world's heaviest). RDG abated their half of the problem during WWII by boxpox cross-counterbalanced center drivers and tapered main rods for the 2-10-2's.

Phil Mulligan


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 Post subject: Re: Was Superpower Oversold?
PostPosted: Tue Jun 28, 2022 7:50 pm 

Joined: Thu May 24, 2012 1:37 pm
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Quote:
"... the faster you go, the less power you have to accelerate; so maybe the trains they ran simply made operation above 40 impossible.
"


Perhaps a better term might be 'made operation above 40 uneconomical' -- but that presumes operation by the time you reach 40 is still economical. Augment is not the only problem; valve limitations even with reduced cutoff and exceeding effective grate limit may also be involved.

There are historical records that demonstrate what may be a profound loss of effective horsepower both in an absolute and relative sense. One very famous one noted that a NYC Hudson had greater horsepower than an N&W Y-class above a certain not-very-high speed.

One very notable, if not often remarked-on, issue is just how quickly a locomotive that is valve-limited can run out of speed. Perhaps the poster child was the C&NW E4b that AAR tested in 1938: it made a great show of bouncing drivers on film, and couldn't get the test train above 100mph, despite being a near sister to a Milwaukee F7 Hudson. Meanwhile, the ATSF 3460 class could relatively easily reach 100mph, but would hard put to get to 105 and would only see 110 with gravity assist... off a high bridge. This despite their being touted as "120mph locomotives".

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 Post subject: Re: Was Superpower Oversold?
PostPosted: Thu Jun 30, 2022 3:42 am 

Joined: Fri Mar 05, 2010 3:41 am
Posts: 3911
Location: Inwood, W.Va.
SD70dude wrote:
A high top speed and power at speed count for a lot less if you have to take water every 40 or 50 miles.......


This comment reminds me of some recollections by a former Chesapeake & Ohio engineer in Stuart Luethner's "The Railroaders."

I don't have the book in front of me, so I'm going from memory, but as I recall, the C&O had a manifest train out of Russell, Ky. that was supposed to run all the way to Cincinnati, with no stops. Power was normally one of C&O's AMC-designed K-4 2-8-4s, which had tenders rated for 30 tons of coal and 21,000 gallons of water. Train length was typically about 100 cars on this river grade line. Mileage today from Russell to Queensgate Yard is 137 miles, but at this time the terminal was actually short of the big Ohio city at Stevens Yard, at Silver Grove, Ky. a still impressive 124 miles.

According to the engineer who was interviewed, a lot of times the engines would arrive in Silver Grove with very low water levels in the tender, and on occasion even with no water in the tender! What did matter was a full glass on the boiler; that was enough to get the locomotive to the engine terminal.

The same engineer also recounted how one man managed to make the run with 106 cars, and he was bragging about it. What he didn't talk about was that his tender was dry and the boiler level was low, too! He had to take on water just to get into the yard--which was a source of ribbing to deflate his boasting.

In any case, it sounds like the margins of safety regarding the water supply were on the low side.

Another story, regarding the N&W, was how auxiliary tenders allowed the road to boost tonnages and speed up operations at the same time. Seems the ability to run without stopping for water meant trains didn't have to restart in some places where that was more difficult than just running straight through.

https://www.steamlocomotive.com/locobas ... road=co#55


Last edited by J3a-614 on Sun Jul 03, 2022 2:23 pm, edited 2 times in total.

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 Post subject: Re: Was Superpower Oversold?
PostPosted: Thu Jun 30, 2022 8:16 pm 

Joined: Thu May 24, 2012 1:37 pm
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Ed King has the detail of the auxiliary-tender plan on N&W -- as so often with N&W, it was masterfully planned and competently executed (See 'The A - N&W's Mercedes of Steam'

The other half of that was that the locomotives sometimes arrived with almost all the fuel in the tender consumed. Even slight unanticipated delays or greater train resistance might get either fuel or water unexpectedly tight...

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 Post subject: Re: Was Superpower Oversold?
PostPosted: Fri Jul 01, 2022 4:22 am 

Joined: Thu Apr 14, 2005 9:34 pm
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Location: Copenhagen, Denmark
Think of it another way, with steam technology, water consumption increases exponentially with speed. The time saving at high speed is lost if you have to make an additional stop to take water.

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