What are the main differences between the SD40 and the SD40-2?
Updated electrical systems and compenents in the -2.
So there are really no differences in the look of them, any detail changes on the outside?
Thanks for the info, Lance
The SD40-2 is 3’ longer, and most ride on HT-C trucks rather than Flexicoils.
The frame of the SD40-2 is 3’ longer than that of a SD40, but that is hard to spot. There are other spotting features, the problem is that many older SD40s received these features as the result of upgrading, or wreck repairs. The only other sure thing is if the unit has the free-flow traction motor blower duct, the problem is that only those SD40-2s built in 1981 or later got that design, hence about 95% of the SD40-2s lack that feature as well.
Another spotting feature is the “sight glass” towards the back of hte long hood on the side door.
There are a few that have already been described and your welcome.
If you were talking about 30 years ago, you could probably tell the difference, but since that time, massive upgrade programs such as Southern Pacific’s General Rehabilitation and Improvement Program (GRIP) rebuilt SP’s SD-40/45 fleet into full Dash 2 specification, which means it takes very close inspection to tell between the earlier and newer models after the rebuilds.
As built, the SD40’s frame length is 65’ 10", the cab roof did not have the rear over hang, no water sight glass window on the engineers side of the long hood and they were equiped with flexicoil trucks. Also they had the older electrical control system of large relays in the electrical cabnet. During the rebuild process the electronics would be upgraded to the solid state style of the -2’s (provided that they had an available -2 electrical cabnet), the water sight glass window may or may not be installed. The giveaway on the rebuilt SD40’s would be the lack of the rear cab roof over hang and the older flexicoil trucks.
As built the SD40-2 frame length is 68’ 10", the cab roof had an over hang, a water sight glas window on the engineers side of the long hood and they were equiped with the HTC flexicoil truck. The locomotive elecrical control system was of the solid state modual design. The only railroad that bought SD40-2’s equiped with the older flexicoil truck was Conrail.
Bob
Here is a SD40M-2 of brazilian MRSL fleet. EMD use the same SD38M frame to do this locos to Brazil as SD40M. later they were modernized to dash 2 line. Note the front and the rear of it. It´s the main difference of SD40-2.
I hpe everybody can see the pictures. If you can´t see them, look here:
Wow, thanks for all the info. Pedrop it is cool to see what they were modernized to as shown in your pix. Thanks so much for those.
its VERY easy to spot! [:D]
you can tell the difference between a SD40 and a SD40-2 from miles away, the differences stand WAY out.
The SD40-2 has huge porches, the SD40 does not.
longer porch in the front, much longer porch in the rear:
drawings from: http://paintshop.railfan.net/
The difference is most noticable in the rear of the engine. Look at the last axle on both engines…on the standard SD40 the rear axle is even with the end of the longhood. But on the SD40-2 the rear axle extends WAY out beyond the end of the long hood, resulting in that classic SD40-2 “long porch” in the rear.
The same thing happens in the front, but not to as great a degree…but the front of the dash-2 also has a larger porch than the SD40.
very different looks between the two locos.
Once you know what to look for, you can tell them apart in a second.
Scot