Steam & Excursion > Steam Files PRR #14

PRR 6200
Class S2 6-8-6

Recently TO member dcoursey sent me the attached photo of PRR 6200 and asked me to include it in the PRR steam files series. So today we will look at the PRR S2 class.
This is another one of a kind on the roster and once again a prototype built during WWII and another one that was not successful. Leave it to the PRR !

PRR was focused on the development of new high speed, high horsepower coal fired steam power that would emulate system-wide the efficiency's and operations of the electrified lines in the east, what we refer to basically today as the Northeast Corridor, a term not yet coined in those days. Baldwin and Westinghouse-Electric teamed up in the mid-1940's to produce a steam turbine locomotive they felt would be able to compete with the new diesels in the coming post-war years. The result was PRR 6200 which was designated as Class S2. The original S class locomotive had been the pre-war duplex-drive 6-4-4-6 "Big Engine", another unsuccessful prototype.

The locomotive was completed in September 1944 and delivered to the PRR (probably after Baldwin and W-E testing) on November 28, 1944. Reportedly due to WWII issues, the locomotive did not go into service until March 26, 1945. WWII materials shortages and restrictions also came into play as the original design had to be modified as lighter weight materials were not available so instead of a 4-8-4 wheel arrangement it became a 6-8-6.  PRR dubbed it "the simplest locomotive of any kind in the U.S." There were no cylinders, no pistons and no valve gear, simply two turbines connected to the center drivers via a double reduction (18:5:1) gears which in turn were connected to the outer drivers via side rods. The forward turbine was rated at 6900 hp and the reverse turbine was rated at 1500 hp. Control was through an ingenus patented fluid power controller (see image #2). 

The coal burning S2 was touted as being able to do the work of a 6,000 hp set of diesels, with no dynamic augment issues and at less acquisition cost than the diesels. Baldwin figured this may have appeal to the overall railroad industry in the steam vs. diesel debates then on-going. The steam builders in those days still saw a need, desire and future of steam, even in the new diesel era. Sadly that was a poor outlook. EMD certainly had other visions. After release, the locomotive tested on the 283 mile Fort Wayne Division between Crestline, OH and Chicago. On March 30, 1945, hauling a 17 car train under charge of Engineer F. Cartwright and Fireman M.E. Brown it attained a a speed of 110 mph which it held for 29 miles according to dynamometer car test records. Later the locomotive was put on the Altoona Test Plant where it was recorded as developing 7245 turbine HP at 66mph. The previous year, PRR had announced it was going to further up the ante in this line of new steam technology and build at Altoona a monster 9000 HP tri-plex locomotive designed by Baldwin / W-E).  Nothing else was really heard about this project and it was soon forgotten. PRR may have been having second thoughts about such things as by December 1944 they were testing N&W Clas J  #610 on the Fort Wayne Division where the 4-8-4 performed well at speeds into three digits. Impressed as they were, they still seemed focused on the Q2's, T1's and by now looking at diesels and trying to figure out what the new S2 was going to be all about for sure.

Strangley the S2 was everthing the diesels were not:

Coal burning
Inefficient at speeds below 40 mph (high fuel and water consumption / unit of power)
One big 6000 HP building block of power that could not be split up into smaller units
Low Availability
Poor Reliability
High Maintenance Costs
Not conducive to off the shelf simple component parts changeouts
Complex, technical and one of a kind.

In 1948, the 6200 was exhibited at the Chicago Rail Fair, most likely where the attached photo from dcoursey was taken.

Due to turbine blade damage, the locomotive was set aside in June 1949 and then scrapped in 1952 after only accruing 103,000 miles. Meanwhile the now ancient K4s's and M1's soldiered on, now increasingly in the company of diesels. 

Specs:

68 inch drivers
310 psi Belpaire fire tube boiler
Forward Turbine; 6900 HP, Rear Turbine;1500 HP
Tractive Effort; 65,000 lbs. (note the low T.E. vs. a set of three E7's or four F7's.



Edited 5 time(s). Last edit at 07/07/25 15:29 by train1275.

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And how many of us had the Lionel version as kids?
https://postwarlionel.com/671-lionel-lines-or-pennsylvania/

mike woodruff
north platte ne

Thanks for posting this - It's truly fascinating.
Bob

" ... on the Altoona Test Plant where it was recorded
as developing 7245 turbine HP at 66mph."

The plant could measure the output of the turbine itself?
While the engine was doing 66 mph on the rollers?
They must have measured the wheelrim horsepower
as well -- wonder how much less it was.

Double reduction gears -- so the turbine and the wheels
turned the same direction? The left-side pipe in the pic
is the exhaust from the reverse turbine, and the right-side
pipe that most pics show is the exhaust from the forward
turbine?

swaool Wrote:
-------------------------------------------------------
> And how many of us had the Lionel version as
> kids?
> https://postwarlionel.com/671-lionel-lines-or-penn
> sylvania/
>
> mike woodruff
> north platte ne

Still have mine! I got lots of enjoyment out of it as a young lad! 

Locoinsp Wrote:
-------------------------------------------------------
> swaool Wrote:
> --------------------------------------------------
> -----
> > And how many of us had the Lionel version as
> > kids?
> >
> https://postwarlionel.com/671-lionel-lines-or-penn
>
> > sylvania/
> >
> > mike woodruff
> > north platte ne
>
> Still have mine! I got lots of enjoyment out of it
> as a young lad! 

Geez, and look where that lead you!!

Posted from Android

train1275 Wrote:
-------------------------------------------------------
> Locoinsp Wrote:
> --------------------------------------------------
> -----
> > swaool Wrote:
> >
> --------------------------------------------------
>
> > -----
> > > And how many of us had the Lionel version as
> > > kids?
> > >
> >
> https://postwarlionel.com/671-lionel-lines-or-penn
>
> >
> > > sylvania/
> > >
> > > mike woodruff
> > > north platte ne
> >
> > Still have mine! I got lots of enjoyment out of
> it
> > as a young lad! 
>
> Geez, and look where that lead you!!
>
> Posted from Android

Hmmm, never thought of it like that! Now you're gonna make me rethink my misspent youth and then that fateful decision to go railroading!!!! All because of playing with a Lionel steam turbine model! Yikes!



Edited 1 time(s). Last edit at 07/07/25 17:01 by Locoinsp.

I figured with some of the escapades you and I went through you would have rethought that youth and your situation at the time!! I sure have!! But what a colorful cast of characters we met and unexplainable situations we found ourselves in.

Posted from Android

Some of the analog mechanical control systems that were built back in the day were pretty amazing.  

I have a copy of the scrappers report somewhere around here that I'll find and scan. It was scrapped at Crestline, Ohio.

Scrappers had to report? Report what?

timz Wrote:
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> Scrappers had to report? Report what?

I believe that the ICC had reporting requirements related to the final disposition of the boiler under pressure vessel regs. So the scrapping of the boiler would be a reportable.
Boilers were thoroughly documented from birth to death. This would have supplemented the required "Locomotive Historical Record Card"  and boiler record cards which usually would document the sale of the locomotive either to the scrapper or to another railroad or ownership.

Maybe someone can elaborate further as to verify this understanding  ..... or not.

Any thoughts on why they didn't use a shaft and gearing arrangement to connect the drivers, instead of side rods?  No room between the drivers and boiler?  Metallurgy of the time not up to the task?  Familiar with side rods, not with gears?  Other?

They could have had perfectly balanced drivers at all speeds.

sf1010 Wrote:
-------------------------------------------------------
> Any thoughts on why they didn't use a shaft and
> gearing arrangement to connect the drivers,
> instead of side rods?  No room between the
> drivers and boiler?  Metallurgy of the time not
> up to the task?  Familiar with side rods, not
> with gears?  Other?
>
> They could have had perfectly balanced drivers at
> all speeds.

I don't think there would have been near enough room for a gear box and connecting shafts in the space available without significantly extending the wheel base.
Also, I can't imagine trying to work on it or service it if it could be devised and then between that and the turbine steam inlet to drivers 2 & 3, the nightmare of trying to drop and install wheelsets. Not even sure how that would be done for things like tire changeouts. Maybe some special drop table tooling to rotate or hold the gearbox and shaft in line. Maybe someone else has another take or angle on it. It is enough for me to just shake my head over such a creation to begin with. Lots can be said for simple rods and a little counterbalancing. Somehow "perfect" in the overall scheme of locomotives has never existed. At least in my world. You get one thing but pay for it with another.

And another thought, looking at that air reservoir ..... well what could possibly go wrong ?!



Edited 1 time(s). Last edit at 07/10/25 10:01 by train1275.

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> They could have had perfectly balanced drivers at all speeds.

No doubt the S-2's drivers were balanced perfectly
good enough, with no reciprocating mass to worry about.

The crankpins still had to be quartered -- most likely
the drivers were cross-balanced?

timz Wrote:
-------------------------------------------------------
> > They could have had perfectly balanced drivers
> at all speeds.
>
> No doubt the S-2's drivers were balanced
> perfectly
> good enough, with no reciprocating mass to worry
> about.
>
> The crankpins still had to be quartered -- most
> likely
> the drivers were cross-balanced?

The side rods would still be reciprocating mass.  There are clearly balance weights on the drivers.

The counterweights balance the rotating siderods. Nothing is reciprocating.