Steam & Excursion > This Railroad Put More Than The Average Work Into This Engine!

Steam locomotive maintenance called for enormous amounts of labor and materials back in the day.  However there were times that the shop forces were given even more daunting tasks when it came to these steam beasts.

Beginning in 1906 the Northern Pacific Railroad started ordering a small fleet of 2-6-2's in the hope that they would be more economical than the larger 2-8-2 that they already had in service.  These Prairies were given the designation as the "T" Class on the NP.  Unfortunately they were met with mixed revues from both the operating department and management due to their limited power and still excessive fuel usage.

In 1918 when NP was faced with a delay in the completion of the latest order of W-3 2-8-2's they decided to implement a plan they had hatched back in 1914 to convert a number of the T-Class 2-6-2's in to 2-8-2's and designate them the W-4 Class.

The Brainard shops of NP were tasked with this huge and complicated conversion of 6 of these Prairies.  The process included replacing the 21 x 28 inch cylinders with larger 24 x 28 inch ones.  Also the front course of the boilers were lengthened as was the combustion chamber.  The boilers were all superheated in the process giving the engines 35% more heating surface than before the conversion.  New frames were ordered for the new longer running gear.  The boiler pressure was increased to 200#s in the process.  This was quite a process!

In this fine photo taken at Glendive, Montana in September 1934 we see NP #2502, one of these 6 converted 2-6-2's in her new W-4 form.  These 6 converted engines were quite successful and well received by all who operated them..They were very fuel efficient and had 62% more pulling power than in the original 2-6-2 form.  However the $15,000.00 cost per conversion brought a halt to the process.

The W-Class 2-8-2's finished their operating career on NP's Yellowstone Division.  They served well there until finally being bumped by diesels in the late 1950's.  Thus ended one of the most ambitious assignments ever given to a railroad's steam backshop.

Martin



Edited 5 time(s). Last edit at 08/27/16 04:39 by LoggerHogger.

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Very interesting, Imagine what that would cost today!

Guess that explains why they have the switcher-style NP headlight

pt199 Wrote:
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> Very interesting, Imagine what that would cost
> today!

Roughly $270,000

Posted from Android

I get around $240K but we are definitely in the same ballpark!

But in reality, to do it today you'd need to add at least another zero behind the dollars - $2-1/2 million might be just enough.  Lovely photo though.
 

One wonders what just adding superheaters alone might have done.  My understanding of the thermodynamics is it would increase horsepower and save fuel.  Though it wouldn't help start a train from a standstill, nor make the wheels less slippery under load.
- Kit (former aerospace thermodynamicist).

Kit Courter
Menefee, CA
LunarLight Photography

CimaScrambler Wrote:
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> One wonders what just adding superheaters alone
> might have done.  My understanding of the
> thermodynamics is it would increase horsepower and
> save fuel.  Though it wouldn't help start a train
> from a standstill, nor make the wheels less
> slippery under load.
> - Kit (former aerospace thermodynamicist).

The Milwaukees experience showed limited success with adding superheaters to its prairie type engines.  Superheating does not increase tractive effort.  I'm not sure if it increases horsepower, or not.

When they built the Pacific extension they decided that the praire, not the mikado, would be their engine of choice and in 1907-1909 obtained 195 of 'em from Brooks and their own shops in Milwaukee.  These engines were near duplicates of the NP's.

These engines were found to be unable to do what was expected of them - double- and triple-headers were common on freight, and in passenger service they were limited to 45 mph. 

Milwaukee superheated 70 of them, then gave up on that program, and all but 55 prairies were scrapped by 1937.

Slipperyness wasn't a problem as their factor of adhesion was a whopping 4.7 when built, and 4.5 when boiler pressure was increased from 180 to 200 psi., which did increase tractive effort from 31,433 to 33,200 lbs.

Starting in 1909 they started buying/building 2-8-2's, and eventually wound up with 500 of 'em.

-John

Santa Fe had a ton of Praries, seemed to do very well with them, sure a bunch of them left around.

Out

LarryDoyle Wrote:
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> CimaScrambler Wrote:
> --------------------------------------------------
> -----
> > One wonders what just adding superheaters alone
> > might have done.  My understanding of the
> > thermodynamics is it would increase horsepower
> and
> > save fuel.  Though it wouldn't help start a
> train
> > from a standstill, nor make the wheels less
> > slippery under load.
> > - Kit (former aerospace thermodynamicist).
>
> The Milwaukees experience showed limited success
> with adding superheaters to its prairie type
> engines.  Superheating does not increase tractive
> effort.  I'm not sure if it increases horsepower,
> or not.
>
I would say it absolutely does increase the available horsepower, all things considered. OR, as it was usually advertised, it cuts fuel and water usage considerably for the same amount of work performed. But usually this translates to more available capacity at a given speed. Like you said, it does not increase the starting tractive effort.

Normally when superheated there is at least some available BP increase which would effect TE but
certainly not at the same pressure. This could be also accomplished by turning the blow down nozzle
90 degrees (to the rear) and blowing down on start up, has had a hell of an effect on Fuel Funny Cars!

Out