M636C Apart from the dynamic brakes, the carbodies above the frame should be exactly the same on a standard GP40-2 and SD40-2. The dynamic brakes are larger on the SD40-2 because they are braking six motors rather than four. This is nothing to do with extended range dynamic braking which would apply to both four and six motor units. For a model, just replacing the single dynamic brake fan with two of the same type would probably do. It would be best to use a set of plans to size the new frame.... M636C
Apart from the dynamic brakes, the carbodies above the frame should be exactly the same on a standard GP40-2 and SD40-2.
The dynamic brakes are larger on the SD40-2 because they are braking six motors rather than four. This is nothing to do with extended range dynamic braking which would apply to both four and six motor units.
For a model, just replacing the single dynamic brake fan with two of the same type would probably do.
It would be best to use a set of plans to size the new frame....
M636C
The carbody above the frame is longer on the SD - note the extra length between the cab and the engine compartment. As mentioned, the double fans are to cool off 6 traction motors of BEMF.
Jim
Modeling BNSF and Milwaukee Road in SW Wisconsin
Thanks!
Beyond the obvious chassis and truck differences, how do the carbodies compare between the two? Looks like the dynamic brake blister for the SD is longer with a second fan, which I presume is extended range dynamics. Since the blister is longer, I suppose that means the SD carbody is longer as well. Any help you could provide woudl be appreciated.
I got a large scale GP40-2 carbody that I'm contemplating upgrading to an SD40-2 as long as it doesn't require too much surgery.
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