SD 40s?

[rambo1]

I just want to know the difference between sd40s sd40-2 and 3s thanks rambo1.....

[silicon212]

The SD40 was built from 1965 through 1971 and is the original in the series.  The -2 includes improved wheelslip control, electrical components (the electrical system with the -2 is modular), and other various improvements to the original SD40.  The -2 version of the SD40 is 3' longer than the SD40 to accomodate the new, improved HTC truck which has all 3 motors facing the same direction (the original Flexicoil truck has the inboard motor reversed vs. the other two which led to some wheelslip control issues), without sacrificing fuel capacity.  One spotting feature of the -2 version over the original is the rather large back porch.  This locomotive was produced between 1972 and 1986.  The -3 isn't an official EMD designation as there were never any factory -3s made, but the -3 is a rebuild which includes a microprocessor control similar to a GP/SD60.

[WSOR 3801]

 SD40

SD40-2

The -2 is longer, longer trucks and parts of the carbody are longer.  The SD45-2 shares the same frame as the SD40-2.  The SD45-2 carbody needed to be longer to accomodate the 20 cylinder engine, and non-flared radiators.   The trucks are also longer, but the fuel capacity remained the same (4000 gallons). 

[carnej1]

silicon212

The SD40 was built from 1965 through 1971 and is the original in the series.  The -2 includes improved wheelslip control, electrical components (the electrical system with the -2 is modular), and other various improvements to the original SD40.  The -2 version of the SD40 is 3' longer than the SD40 to accomodate the new, improved HTC truck which has all 3 motors facing the same direction (the original Flexicoil truck has the inboard motor reversed vs. the other two which led to some wheelslip control issues), without sacrificing fuel capacity.  One spotting feature of the -2 version over the original is the rather large back porch.  This locomotive was produced between 1972 and 1986.  The -3 isn't an official EMD designation as there were never any factory -3s made, but the -3 is a rebuild which includes a microprocessor control similar to a GP/SD60.

EMD did in fact offer a factory remanufactured unit in their catalog with the model name SD40-3. Only a couple were completed:

http://www.rrpicturearchives.net/showPicture.aspx?id=17332

Other rebuilders and in some cases the RR's themselves offered lower priced conversions to -3 specs and EMD never had orders for their version..