Q: Identify this appliance on steam loco please (for the 0-6-0 project)

[mmagliaro]

Hey there bright young ladies and gentlemen, can you tell me what this "thing" is, circled in red in the photo below?
Yes, I know it looks like some sort of air tank.  But also note what appears to be a linkage coming out the front connected to a lever (identified by the arrow).  So is this some sort of piston?  A power reverse?

Thank you for your insightful comments.

[wcfn100]

Brake cylinder?

Jason

[Chris333]

Defiantly power reverse since it's connected to the reversing linkage. Kato FEF might have one like that.

[wazzou]

Power reverse.

[wcfn100]

So what type of valve gear is that then?

Jason

[wazzou]

Blasphemy.     See below.

[mmagliaro]

I don't think this is Walschaerts valve gear.   Here's more of the side showing the valve gear.  There's no eccentric crank, or the union or expansion links.  I've been wondering just what the heck this valve gear actually is, now that you mention it.
EDIT:  So, I guessed it must be Stephenson owing to the lack of any of the standard Baker or Walschaert's linkages, and
apparently Stephenson is correct.  That's what the Shrenk & Frey book says ("Northern Pacific Classic Steam Era").

[wazzou]

Well, I think it might be Stephenson because it matches the Valve gear of most of the NP's Q Class 4-6-2's and they had Stephenson Valve gear.

I'll ask my Uncle.


Edited after thought and picture review but no conversation with Uncle, yet.

[wcfn100]

I'm not doubting that it's a power reverse, but Chris, it doesn't look connected to the piston rod to me, at least not at that angle in the photo.  Unless I don't know what I'm looking at which is very likely.

Jason

[narrowminded]

It looks to me like a positioner control device for the power cylinder below.  I used such things on industrial hydraulic and pneumatic cylinders in industrial applications.  It will position and hold a balanced position on a cylinder based on a signal pressure... If that's what it is.

[mmagliaro]

It is Stephenson valve gear.    Notice the little rod above the valve slider that goes into the valve box above the piston.
The back of that little rod connects through a linkage to cams on the inside on a driver axle.  That's how the valve is timed to the drivers.
I wasn't completely certain because I'm no expert at this, but the Shrenk & Frey book is a very trustworthy source and they confirm it.

[Chris333]

All the valve gear is between the frame rails hidden from view.

This video shows it, even the reverse lever.

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http://media.finedictionary.com/pictures/9/47/12041.jpg

They are just using steam assist to move the "lever", like power steering.

[peteski]

I would think that since the eccentrics are hidden, this would be Stephenson Valve Gear (or something similar).

https://en.wikipedia.org/wiki/Stephenson_valve_gear

[wazzou]

whoops...yeah I edited my post.  I'm not sure why I said Walschaerts when that is clearly the easiest to identify.

[Chris333]

If you look at NP 0-6-0 1070 it has a reverse power reverse.
http://vignette1.wikia.nocookie.net/locomotive/images/6/62/Northern_Pacific_1070.jpg/revision/latest?cb=20140112212719
This one too:
http://transport.castlegraphics.com/albums/railroad/steam/np/switcher/np_1081_0-6-0_tacoma_wa_may15_1936.jpg