Help reading dimensions on loco erecting drawing

[mmagliaro]

In the drawing below, look at the "9" x 12""  on the end of the driver axle.



Is 9" the diameter of the actual axle?  (i.e. .056", which is darn close to 1.5mm in N Scale)
Is 12" the outside diameter of the bearing?  (i.e. .075" in N Scale)

So when one looks at the outside face of the driver, does that 12" translate to the large flat circular
area we see on the outside of the wheel (marked here by the red line) ?

[wcfn100]

That's not the journal box? If so, I think that means diameter (9") and length (12").

Jason

[Sokramiketes]

That's not the journal box? If so, I think that means diameter (9") and length (12").

Jason

9x12 is a standard journal size, so I'm going to go with Jason's description as well.

[mmagliaro]

Based on other dimensions marked on the drawing, and scaling off those in a drawing tool,
the diameter of that circle in the center, which looks like the axle, is 9".   And this isn't a "sketch"; this is
an actual to-scale loco drawing.  The journal box looks like it's much wider.

Here's another version from blueprint.

The axle (circle) diameter isn't indicated on this one, but from the other nearby dimensions, it was easy
to measure and confirm that that circle is 9" in diameter.

[mmagliaro]

I looked on another plan book I have, and does state that this engine had 9x12 journals.
Now I am confused.  What is that circle on the drawing?  Isn't that the axle?

[victor miranda]

need more drawing...

looks like a Stephenson valve system.

I suspect the circle described inside the axle is the arc or
where the center of the eccentric travels.

it is a virtual point.  and the valve rods are drawn and then made based on that.

so the valve link arc has to be generated from that circle....

.... calculated dimensions and then some machinist has to find a way to make the parts.

victor

[Cajonpassfan]

I looked on another plan book I have, and does state that this engine had 9x12 journals.
Now I am confused.  What is that circle on the drawing?  Isn't that the axle?

Max, I believe the dimensions refer to nominal sizes of the axle opening and the inside width of the journal/bearing block.The circle in the first drawing represents both the axle and the opening (which of course are not exactly the same, the axle being just a tad smaller to allow for lubrication). The block moves up and down and the dashed circles in the second drawing represent extreme positions.
You're going to model this in N scale?
Otto

[Sokramiketes]

Max, you need a drawing of the wheel casting to know the dimension you are after. The bearing is a measurement of the bearing surface (inside dimensions) and you can determine the axle diameter from there (the 9"), but nothing about what is a flat surface on the driver itself.

[mmagliaro]

Thanks, Mike.  I was kind of afraid of that.  Well, here's to eyeballing and scaling it off a lot of photos!   

[Cajonpassfan]

Now I am confused...what flat surface on the driver?
12" is the nominal dimension of the frame opening in which the journal box floats vertically.
9" is the size of the axle/opening.

This is as clear an illustration as anything I've ever seen, very similar to your loco.
Otto K.

[Cajonpassfan]

Oh, now I see what you mean by the flat area on the driver...
I'm pretty certain it's both the axle and the wheel hub casting, it's just showing as one piece in the fuzzy photo.
Typically, they were constructed like this:
Otto