Test fitting the small black fans (Red Caboose GP-9 detail parts) to the long hood. I can’t see the larger fans fitting. 🙁

Coupler Pad

I have no idea of the proper name for this but ‘coupler pad’ is good enough for now. The couplers are slid through the coupler pocket on the shell and under the pad. A screw then is used from the bottom of the coupler through the pad. This effectively secures the shell/body to the mechanism.

Pad and SD40-2 shell

Here we can see the couple pad in relation to the coupler pocket in the SD40-2 shell. Note that the bottom of the pad is even with the top of the coupler pocket/opening – the red line enhances that.

Pad and Test Print

At some point I aligned the pad with the wrong surface. Here in the test print the pad is aligned with the bottom of the couple pocket/opening – the red rectangle is the pad. I need to align the bottom of the pad to the top of the opening (orange rectangle). Basically the entire coupler opening needs to be moved down the height of the opening.

Sectional View

A sectional view of the mechanism, frame, BB section and cab (call this ver 11 .. just a number so I can keep track). Pay particular attention to the 6.917mm dimension. This represents the distance from the face of the pilot to the center of what I am calling the coupler pad. The hole is threaded for the coupler screw. That dimension is most likely wrong .. this is simply the measurement off of the CAD drawing. I need to assemble the mechanism back into the original Athearn shell and get the exact dimension and do the same with my printed frame and adjust as needed.

The point though is that this needs to be the same as the Athearn dimension. This in turn tells us where the pilot ends. Knowing that gives us where the end of the hood needs to be depending on the width of the walk in front (I use 30″). Everything is related.


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