Hey all, first, before all the welcomes, I'm the poster formerly known as trainboy. this is the user name I tried to use originally, but the email screwup ate it. Anyway, onto my question. EMD has lost me, I stopped paying attention for a few years and they lost me. I fully understood the SD-60/M/MAC and I think I understand the SD-70 (still 4000hp?) but After that I'm fuzzy. SD-75M/I (I understand Isolated I think) SD-80, SD-90, SD-9043 (what's with the GE/SD-45 Flares?). Can anyone help me sort this out? Or point me to a good resource. EMD seems to not tell me much. My Parents live a mile from the Riverforest Station on the Old Chicago North Western West Main and I see the Big UP SD-90s, but it took me a few times to realize they were EMDs. Thanks
Well welcome, lets get that in first!!! As you say, on the 60 series (and onwards) the M designated a full width nose, and AC designated AC traction. You are correct that the I is for an Insulated cab, These codes have carried on to the present lines, although I think I read that they are starting to drop the M/I designation on new builds as they no longer build spartan cabs. They also didn't use IAC (which would have been logical for an insulated cab AC loco) and the only thing I can think of is that it's not as snappy a title! The 70 series uses the 16 cylinder 710 series engine, usually giving about 4000hp, and that gives you SD70, SD70M, SD70MAC, SD70I, SD75M and SD75I models in exactly the same coding method as the 60 series. The 75's i'm told have some kind of different control system which rates those units about 300hp higher. The 80 series (so far only one build of SD80MAC for Conrail, now split between NS and CSX) uses a 20 cylinder version of the 710 engine to produce 5000hp, the larger engine size presumably dictated using the larger bodyshell. These are kind of a halfway house between a 70MAC and a 90MAC The 90 series gets complicated, these were meant to be 6000hp units, using a power unit from another manufacturer (not the EMD 710 series engines) so on UP you now have SD90MAC's, which are 6000hp, and SD9043MAC's, which have a 16 cylinder 710 engine installed (making them essentially very big SD70MAC's) giving only 4300hp. The idea *was* that these could be upgraded when they got the 6000hp units working right, AFAIK this hasn't happened yet. Possibly somebody out there can update us on the story, and where things are going on particular railroads at the mo, UP were unhappy with the 6000hp units last I heard, but things change. Oh, the angled rads.... AFAIK, the reason some of these designs have angled rads is the same reason that the SD45 had them, the need for a larger amount of radiator area in a given vertical height of bodywork. Mounting the radiator at an angle lets it be taller without sticking out of the top of the loco. They are a feature of the 80 & 90 series, and there are some UP SD70M's out there with this too, but I don't know the background of why those needed bigger radiators, anyone else? [ 08 January 2002: Message edited by: Martyn Read ]
Martyn, I think you covered the macs quite well. Most railroads shied away from the 80macs because of the 20 cylinders and possible appetite for fuel and that the last 20 cylinder loco (SD45) had crankshaft problems. I used to see the 80macs up close and personal a lot on the Conrail Boston Line. Now CSX uses the AC6000s by GE. As for the 9043 vs 90macs. Your correct the 90 macs are supposed to get 6000 hp motors. EMD in an effort to keep up with GE or beat GE to the punch offered the 90mac "convertible". EMD wanted to sell the locomotive and told the buyer they could convert to the 6000hp unit when it became available. EMD was then going to recycle the 4300 hp engines either for marine or rebuild use. There is a spotting difference between the 90mac convertible and the 90mac (besides the new ugly short hood). If you look closely on the long hood right before the radiator flare, the 80mac and the 90mac convertible are virtually identical. However, when the 6000hp prime mover is put in there is a modification difference in the long hood that is most evident right before the radiator flare. The shape of the long hood is different. It is hard to describe put if you look at pictures of the 80macs and 90macs you can see the difference. I wish I had some photo's in front of me to describe it better.
They have a modified cooling system (split cooling) in order to help the engine meet new EPA emissions regulations. There is a seperate cooling system for the prime mover, and another to help cool combustion air (the cooler air is denser, and helps provide cleaner combustion). Flaring the radiators out was the best way to make room for all of this and still stay within clearance limits, like Martyn mentioned. So far, there are three in active service, and I've heard reports of several more recently being delivered. The flares on new 70-series units are supposed to be a standard feature. I had a list somewhere of all the UP SD70M numbers that are supposed to be delivered with it, but naturally, now that I need it, I can't find it.
New Question same topic. Why does it appear that they moved the Dynamics to the rear behind the cooling? I thought they were behind the cab to get them away from all that heat?
