What in the world is the difference between an SD40-2 and an SD40-3?

Question

What in the world is the difference between an SD40-2 and an SD40-3?

Answer 1

I have never heard of an SD-40-3 but a lot of times when a RR or other company rebuilds a locomotive they will put their own designation on it.

I wouldnt be surprised if that is the case here.

I am not aware of EMD building an SD-40-3 but . . .. . . maybe.

Answer 2

CSX is operating some rebuilt SD's that have been designated SD40-3.  I can't remember off hand what all the changes are between the 3 and 2.  Part of it is the APU.  I think the 3's are supposed to have less exhaust or something also.

Answer 3

Well, that would be "1" now, wouldn't it...  if there was such a thing as an SD40-3 but, there isn't, to my knowledge.

There was an SD45-T2, however, or what was called a "tunnel motor."  These are easily identifiable by the "see through" louvers at the rear of the cowling immediately above the cat walk.  As their name implies, these engines were designed for use for railroads that had a lot of tunnels or snow sheds, such as the SP had over "the hill."  D&RGW ran tunnel motors as well. The cooling fans are inboard, directly above the grille works.

On conventional EMD locos, the cooling shutters were at the top of the engine to the rear.  This is of course is where most of the hot exhaust fumes from locomotives ahead in the consist was concentrated when running through tunnels and sheds.  Having the air intakes lower on the engine drew in cooler air, helping (but not eliminating) the problem of the prime movers shutting down due to excessive temperature.

But, if ya do find a -3, lemme know, willya.....?

Answer 4

Bob, I think there is indeed a few SD40-3s in use today as I have very much heard of them but cannot remember which railroad operates them.  In any event, they are mostly rebuilds by a few Regional railroads, I believe as none were ever manufactured by EMD this way.  The difference between say a standard, SD40, SD40-2, and SD40-3 is simply in the locomotive's electronics and computer systems/compenents whereas the -2 is upgraded over the SD40 and the -3 is upgraded further over the SD40-2.