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BLI Rolling Thunder concept: compatiblity with RailPro?

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jimw:
Tim:  That last bit about SD7 history is tantalizing.  I had understood the rationale for 6 axle power was to decrease per-axle track load and increase tractive force.  Somehow that seems a little too obvious, so I'll bite:  what's the secret?

Jim W

jimw:
Joe:  Thanks for your thoughts.  Looks like iPhone 4 speakers are the ticket.  I know Bill sells them, so I'll send him an order.  Thankfully my hearing loss has been limited to the high-pitch (read: female) end of the spectrum!  (Boy,  I hope my wife doesn't read this!)

Jim   

G8B4Life:
Jim,

Your rationale is 100% correct but as you say that's the obvious part, the "secret", seeing it doesn't seem that well known is this (I'll try to keep it short, it is a good but lengthy history the whole story):

The very first EMD C-C bogie (truck) that was the genesis of the SD7, which in itself was the genesis of the whole SD line, was not destined for the US market. It was designed by EMD (after much protest from EMD apparently) at the request of the then Victorian Railways here for our first mainline DE locomotive, the ML-2.

However, as it turns out we did not end up with it. Back in those days the mantra here was still very much "buy British" so the US dollar allocation from the Government ended up not being enough for all the parts from EMD for all the locos; A decision was made that the bogies could be made here and to get from EMD those things that couldn't be made locally, such as the engine and traction motors etc.

This left EMD with a pair of very good very usable C-C bogies that had cost time and money to develop doing nothing so as history would have it they streched a GP7 and made the very first model in the SD line, the SD7.

So the part that was genesis of the SD7 and the SD line in general, the three axle three motor bogie was an export item designed at the request from, and for a railway in Australia.
 
- Tim

Alan:
Fascinating.

I assume they had to flip them over for use in northern latitudes. Or is it the wheels spin the opposite direction?  :P

jimw:
Tim:

A photo (but not the interesting embryology) of SP1518 (currently at the Illinois Railway Museum) is on Wikipedia.  The article states it is the first of its class, and hints that it is slightly different from its successors.  Perhaps an update to the article could be of interest?  I would never have guessed your answer!

Jim W

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