The E in E-unit class could stand for Express (Passenger unit) or Elegance?
The M in MAC is a mystery to me
Read page 1 of the thread again
The M in a SD70MAC, SD80MAC and SD90MAC stands for the GM-design two-window or three-window safety cab (as opposed to the CN four-window design denoted by a W).
As you say, the AC in this case stands for AC traction.
Gribble Siding wrote:M in MAC is really simple. M is a W upside down. When GE took over the W designation on their widecab locomotives EMD didnt want their stuff confuzzled with GE stuff. EMD over the years has changed the M designation to mean other things like Modified Widecab or Modified North Amercian Cab, but the original reason was because M is a W upside down.Now the reason you see an M on units like the SD40M-2 or the GP40M-2 is because certain railroads do certain things to certain locomotives on their own, without the help of certain locomotive producers. Thus M stands for "Modification" or "Modified", as they are modified from their original form. An SD40M-2 is basically an SD45-2, but with an SD40-2 prime mover. UP has done this to all the SD45-2s, and SD45T-2s they have, and many that they no longer own. Many SD45-2s, and SD45s(thats for you coburn ;)) that entered into lease fleets like CEFX and HLCX have also done this. BNSF has some GP40Ms, which I can only guess got nudged to -2 specs, and I've been told that there are some GP50Ms on the IC that were former CNW GP50s, brought down to GP40-2 specs. Also note the the M in SD40M-2 is in the middle of the locomotive model, where as on the SD70MAC, its after the model.L stands for lightweight frames. CN was big on these, for a while anyways. There were several C44-9Ls that were not only widecab, but used a lightweight frame. You can see the difference when one of these C44-9Ls (sometimes called C44-9LWs) are paired up with a standard Trash 9. The lightweight framed Trash 9s will actually ride higher. As we dont get alot of CN stuff down here in "The Land Of The Big D" I have only shot one of these lightweight framed Trash 9s linked to a UP Trash 9, and the difference, isnt very noticeable, its was there.There is a U, or actually its a u. These are upgraded locomotives. Upgraded how? You'll have to ask the railroads the upgrade them. BNSF has GP7u, GP9u, SD40u. Who knows what they did. Upgrade the prime movers, or atleast rebuild them, upgrade the componentry, etc. DGNO has a GP7u, and a GP9u that never saw service with BN, ATSF, BNSF. They happen to be parts donors now, you know, Train 15:13(?).
1) The SD40M-2s are not only made from SD45s. There are SDP45s, SD40s, and I think there might have been an SD35 or two thrown in, but I could be mistaken on the last one. I was told (so this is just word of mouth, and maybe not true) that the M in SD40M-2 was for Morrison Knudson, the company that rebuilt them. This is why the ones rebuilt by SP itself did not have the M, but were called SD45r.
2) Different issue, whoever said E was for Eighteen Hundreed HP was correct.
3) Has anyone addressed the "M" in the Dash 8-40CM? These were barn like engines, GE's versions of the SD60F. What was that M for?
Looked through the thread again... on the F unit being 1,400 HP, I don't think that is absolutely true. E untis were eighteen hundred HP, and SC and SWs were six hundred HP, while NC and NWs were nine hundred HP, and that's why they were named such, so it seems to make sense that the 1,350 HP FT was for fourteen hundred, but it was introduced later, and may not have fit in that scheme.
I don't believe anyone knows where FT came from. EMD never said and it hasn't been recorded since, although one theory is that it was "Freight Tandem," and another is that it was "Fourteen Hundreen Tandem."
For what it's worth, the next line that EMD introduced was BL, which stood for "Branch Line."
And of course
TR was "Transfer"
GP was "General Purpose"
SD was "Special Duty."
My point being FT is a mystery. Was it part of the old system or the new system, and if it was the old system, what was the T for?
Reading this thread I noticed some of you have been referring to
B = 4 axles
C = 6 axles
D = 8 axles
shouldn't it be
B = 2 axles
C = 3 axles
D = 4 axles
????
Chuck
Your friendly neighborhood CNW fan.
Lord Atmo wrote:er.... how many 3-axle locomotives do you know about?
Chuck's correct... he's referring to each truck, not the entire locomotive.
The engines are B-B, C-C, and D-D.
I forgot to mention the
A - I - A Trucks on the Alco PA/PB units