Pennsy S1

[superturbine]

 




Jason Smith
Tomball Locomotive Works

[Philip H]

Ok Jason, TIME OUT!

First, that is a seriously cool engine.  So cool it ALMOST makes me want to switch to Pennsy Steam.  ALMOST.

Second, if you don't stop tackling all these projects, you and Ritchie (what with all hi UP steam work) will end up shaming us into taking up knitting.

But if t his is the start of another build thread of yours, I'm all eyes!

[CodyO]

HOLY SH*%
I`m awaiting the shell

[chicken45]

You're killing me dude. That, or you're just one huge troll.

[jdcolombo]

So why was there a six-wheel lead truck?  The six-wheel trailing truck I sort of understand - its function is to support the weight of the firebox, which probably was huge on the S1.  The C&O Allegheny had a six-wheel trailing truck to support the huge firebox, too (though the Big Boy only needed 4).  But in general, the lead truck's function is to "lead" the loco into a curve; was the wheelbase so long that the lead truck needed six wheels to properly get the engine to negotiate curves?  Even the Allegheny, Big Boy and Challenger only had 4-wheel lead trucks despite their size.  Why six?  Was it speed-related?  Or just for symmetry?

John C.

[chicken45]

Ugh. What's the min radius for this sucker?

[superturbine]

Thanks Phillip,

Chicken-
I am not exactly sure what the minume radius is for my T1, which would be the same as the S1 (at least with how I want to build mine) think of it as a  extended GS4.  If a GS4 has a problem articulating on a layout this engine would for sure.  However, there is a possibility of slightly articulating the front engine for those of you with tight raduis layouts who never dreamed of running this engine......... That would be a benefit of a tender powered mech.  The front and trailing truck can be made to articulate very well and as long as they are done correctly and will have no bearing on min raduis.

[pjm20]

So why was there a six-wheel lead truck?  The six-wheel trailing truck I sort of understand - its function is to support the weight of the firebox, which probably was huge on the S1.  The C&O Allegheny had a six-wheel trailing truck to support the huge firebox, too (though the Big Boy only needed 4).  But in general, the lead truck's function is to "lead" the loco into a curve; was the wheelbase so long that the lead truck needed six wheels to properly get the engine to negotiate curves?  Even the Allegheny, Big Boy and Challenger only had 4-wheel lead trucks despite their size.  Why six?  Was it speed-related?  Or just for symmetry?

John C.

The S1 was designed built just before WWII, so there was limitations on what metal could be used. The leading truck was supossed to be 4 axles, but the quality of the metal forced the design to 6.

[Lemosteam]

The front and trailing truck can be made to articulate very well and as long as they are done correctly and will have no bearing on min raduis.

Yes, not only will the lead ant trailing trucks need to pivot they will need to be allowed to slide side-to-side (clearance issues?).  The boiler will have to be balanced fore and aft of the four driver axles, otherwise the boiler will be front of aft heavy and a spring over the lead or trailing truck will be required.

Looks like a fun build.  I'm in for a shell set assuming you are offeering one.  Yes. Jason yoiu will have to cast the lead and trailing truck sideframes for me, again...  Can you please cast in the sheetmetal defomation as shown in the picture too?

[mmagliaro]

I have the brass Oriental Limited version of this engine.   The 2 engine trucks are completely rigid.
(Unlike the Key Imports T1, which allows some pivot in the trucks).

The trailing truck is on a rigid arm that swings left and right (like most steam trailing trucks).
The pilot truck is on an arm AND pivots.  In other words, the arm pivots on the frame and the truck
can pivot on its end of the arm.  But  this is a pretty common design.  Even the Trix K4 pilot and trailing trucks
work like this.  Sometimes, a steam loco has a trailing truck mounted on a wide slot so
the truck can not only swing left/right, but also slide back and forth.  The S1 trailing truck is not like that.
It's just a simple pivot.

Anyway, the brass one can go around 18" curves with no trouble.

As for why I have this rare bird....

Somebody gave it to me.  I was a lucky guy that day.
It has some damage to the paint finish and would have to be stripped and repainted
to really look good again.  it is also missing one valve gear linkage piece and a rivet, but it is
temporarily kludged back together with a piece of wire so that it runs.  It was one of my "someday" projects.

[chicken45]

[mmagliaro]

Oh brother.... Nope.  The S1 is for Jason to build.

[chicken45]

You can check out any time you want, but you can never leave.

I'm excited for this! Does anyone have a preliminary assembly plan?
I'll probably hope to pursue tender drive as it sounds like it will allow for 12" radii.

[Cajonpassfan]

The S1 was designed built just before WWII, so there was limitations on what metal could be used. The leading truck was supossed to be 4 axles, but the quality of the metal forced the design to 6.

Sorry, but that doesn't sound quite right; the WWII materials restrictions didn't kick in until the war and this engine was completed in 1939. IMHO, the answer is weight and a lot of it. When you design something this big and heavy and have only four driving axles to spread its weight over, you need to support the rest of the loco over additional axles, otherwise axle load limits are exceeded. Other super-sized locos, Aleghenies, Challengers, Big Boys etc. had more weight on the driving wheels account they had more of them and thus didn't need six additional axles to spread the weight. As a result, the S1 had less than half its weight on drivers, which turned out to be a part of its slippery undoing. What a beast though!!!
Jason, I'm sure you'll do this engine proud, I'm amazed at your work! Can't wait to see pictures...
Regards, Otto K.

[towl1996]

Ok, so you've covered one end of the alphabet, now let's go to the other end and cover the I's, the M's, and the H's. 
That S1 shell should be "easy" for the master. I'm in if your selling.