cncproadwarrior
North of the 49th
I've looked at pics of both the SD40 and SD40-2 and the only exterior difference that I can see is that the rear platform appears to be longer on the dash 2. Are there any other major exterior differences?
SD40 and SD40-2
- Thread starter cncproadwarrior
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hamltnblue
Active Member
Here's a link that explains the SD40 series pretty good
http://www.american-rails.com/sd40-2.html
Here's another good site
http://www.vnerr.com/divs/BisonRail/Work_Order/SD40-2/SD40-2.html
http://www.american-rails.com/sd40-2.html
Here's another good site
http://www.vnerr.com/divs/BisonRail/Work_Order/SD40-2/SD40-2.html
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kjd
Go make something!
MMM SD40-2s, my favorite.
The SD40-2 frame is 3 feet longer to accommodate HTC instead of Flexicoil trucks. HTCs are longer because all the traction motors face the same way vs the Flexicoils which have two one way the third is opposite. You can see the third motor next to the fuel tank on an HTC truck. The rear of the cab has a slight overhang on the SD40-2 and there is a small window under the radiator intake on the engineer's side to see the water level without opening the door. Often SD40s had the handbrake on a post on the rear porch and the SD40-2 has either a ratchet or wheel on the conductor's side of the short hood.
As usual there are variations in particular units, Conrail SD40-2s (some had Flexicoil trucks), EMD 2000 (SD40 with HTC trucks), BN7023 (wreck rebuild with SD45 radiators), MRL 250 (wreck rebuild with GP40 hoods), BN7890, BN7149 (dual fuel experiments with flared radiators) all come to mind. Then you could get into the different phases of SD40s and SD40-2s and all the variations of grills, louvers, fans, and shapes of the various bulges on a locomotive.
The SD40-2 frame is 3 feet longer to accommodate HTC instead of Flexicoil trucks. HTCs are longer because all the traction motors face the same way vs the Flexicoils which have two one way the third is opposite. You can see the third motor next to the fuel tank on an HTC truck. The rear of the cab has a slight overhang on the SD40-2 and there is a small window under the radiator intake on the engineer's side to see the water level without opening the door. Often SD40s had the handbrake on a post on the rear porch and the SD40-2 has either a ratchet or wheel on the conductor's side of the short hood.
As usual there are variations in particular units, Conrail SD40-2s (some had Flexicoil trucks), EMD 2000 (SD40 with HTC trucks), BN7023 (wreck rebuild with SD45 radiators), MRL 250 (wreck rebuild with GP40 hoods), BN7890, BN7149 (dual fuel experiments with flared radiators) all come to mind. Then you could get into the different phases of SD40s and SD40-2s and all the variations of grills, louvers, fans, and shapes of the various bulges on a locomotive.
The SD40 is 65'8" long, the SD40-2 is 68'10" long. Most of this is in the rear porch, the front porch I believe is the same as an SD40. Which gives the SD40-2 it's famous asymmetry. One of the reasons it's longer is to accommodate the HT-C trucks which replaced Flexicoils as the standards. The HT-Cs are longer and to still allow for a full size fuel tank, the whole frame had to be stretched.
The SD38, SD39, SD40, SDP40, and SD45 all share the same frame and wheelbase.
The SD38-2, SD40-2, and SD45-2 all share the same frame and wheelbase.
Spotting features:
1. HT-C trucks. If it has them it's a dash-2. If not, it may or may not be; both Chessie and Conrail ordered SD40-2s with Flexicoil trucks.
2. Longer (6') long hood porch on the dash 2.
3. "Knockout" rings on the long hood end (dash 2)
4. Offset battery box under the cab on the left side (dash 2)
5. Cab roof overhang slightly toward long hood end (dash 2)
6. Sight glass on right side of long hood (dash 2 and some late 40-series)
Also further evolutions occurred during the long production life of the SD40-2 that you won't find on a straight SD40: the "corrugated" type radiator grills, Q-fans, Q-exhaust (with the bulge in the dynamics), and the 88" low short hood as well as longer "snoot" hoods ordered by the Santa Fe, UP, and others.
When I see the familiar profile, my eye first looks to the top for corrugated grills, which a large number of SD40-2s have. If they have earlier grills, my eyes go down to the trucks. If I see Flexicoils, then I'm looking at the battery box if I can see the left side, or I'm looking for the cab overhang. By then I can make the call. I think the cab overhang is the most reliable dash 2 spotting feature. So far, I've never seen a pre dash-2 loco that has the overhang, and I've never seen a dash 2 without it. I'm speaking of factory built locomotives. Rebuilds all bets are off, shops tend to do whatever they want and use whatever they have. Such as the EL 3657 and 3667, which carry the distinctive spotting features of the SD45-2... and the 3657 even has a dash 2 cab and battery box. But neither are... both are SDP45s internally, rebuilt from a wreck with new long hood components from EMD.
Andy
The SD38, SD39, SD40, SDP40, and SD45 all share the same frame and wheelbase.
The SD38-2, SD40-2, and SD45-2 all share the same frame and wheelbase.
Spotting features:
1. HT-C trucks. If it has them it's a dash-2. If not, it may or may not be; both Chessie and Conrail ordered SD40-2s with Flexicoil trucks.
2. Longer (6') long hood porch on the dash 2.
3. "Knockout" rings on the long hood end (dash 2)
4. Offset battery box under the cab on the left side (dash 2)
5. Cab roof overhang slightly toward long hood end (dash 2)
6. Sight glass on right side of long hood (dash 2 and some late 40-series)
Also further evolutions occurred during the long production life of the SD40-2 that you won't find on a straight SD40: the "corrugated" type radiator grills, Q-fans, Q-exhaust (with the bulge in the dynamics), and the 88" low short hood as well as longer "snoot" hoods ordered by the Santa Fe, UP, and others.
When I see the familiar profile, my eye first looks to the top for corrugated grills, which a large number of SD40-2s have. If they have earlier grills, my eyes go down to the trucks. If I see Flexicoils, then I'm looking at the battery box if I can see the left side, or I'm looking for the cab overhang. By then I can make the call. I think the cab overhang is the most reliable dash 2 spotting feature. So far, I've never seen a pre dash-2 loco that has the overhang, and I've never seen a dash 2 without it. I'm speaking of factory built locomotives. Rebuilds all bets are off, shops tend to do whatever they want and use whatever they have. Such as the EL 3657 and 3667, which carry the distinctive spotting features of the SD45-2... and the 3657 even has a dash 2 cab and battery box. But neither are... both are SDP45s internally, rebuilt from a wreck with new long hood components from EMD.
Andy
cncproadwarrior
North of the 49th
Very cool. And thanks for the sites. Also learned somthing new: SD38-2!!!!
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