View Full Version : Locomotive model

07-11-2004, 11:46 PM
After getting into this hobby around the turn of the year, I still have some questions about how locomotive manufacturers come up with the locomotive model number and what the difference between some of them are.

I'm guessing EMD has adopted the Boeing way of numbering their products: sequentially. SD40, SD50, SD60, SD70, SD80, SD90 just like the Boeings 707, 727, 737. 747, 757, 767, 777 (nevermind the 717 or the 7E7!).

But, what is the difference between SD60I and SD60M? I know the 'I' stands for isoloated cab, but what does the 'M' in the SD60M and SD70M stand for? I know the 'AC' in the SD80MAC and SD90MAC stand for alternating current, but what is an SD9043?!?

As if EMD isn't confusing enough, look through the GE products. B, C, ES dash 7/8/9?!? I'm assuming the C40-9CW is 4000 hp, while the C44-9CW is 4400 hp. Is that the difference?

I think I've figured out the rest, but is there anyone out there that can shed some light? Thanks!

E.M. Bell
07-12-2004, 02:06 AM
on Fine EMD products, the "M" simply means the unit is equiped with a wide cab...I is a isolated cab as you said....

SD60M, SD70M ect...

Lord Vader
07-12-2004, 05:25 AM

GP = General Purpose and is 4-axle
The number has nothing to do with horsepower.

SD = Special Duty and is 6-axle

E = Passenger unit, 6-axle, but only 4 are powered

F = Passenger unit, 4-axle, all powered

SW = switcher, 4-axle

MP = same as SW

GE -

U = Universal series. The number does relate to horsepower. The letter designation relates to the number of powered axles per the "White System". A loco with a B-designation is a 4-axle unit. C = 6-axles.

DASH-7, DASH-8, and DASH-9 are series of locomotive design. The number reflects the decade they originated in. The latest GE models are part of the Evolution series to meet EPA emmisions standards, hence the ES designation.

AC is universal to both builders. That denotes Alternating Current traction.

So lets break this down a bit through example.

A GE AC4400CW is an Alternating Current loco with 4400 horsepower, 6- axles, and a safety cab arrangement.

An EMD SD70M is a direct current loco with 4000 horsepower, 6-axles, and a safety cab arrangement.

An EMD GP40-2 is a direct current loco with 3000 horsepower, 4-axles, and an "old standard AAR cab" arrangement. The -2 reflects modifications made by EMD to the original GP40 design.

Hope this helps a bit. Feel free to ask questions!

07-12-2004, 01:10 PM
SD9043 is a SD90 equipped with a 4300-hp 710 series engine but designed to accept EMD's newer H engine at 6000hp.

GE offered the same thing with it's AC6000 convertible. The original FDL engine could be replaced with the GE 7HDL.

07-12-2004, 02:17 PM
I'd like to add something.

The only EMD models that reflect their horsepower rating were the GP18, SD18, GP20, SD24, and SD9043MAC (excluding any rebuilds, i.e. GP15, SD20). The GP30 was originally going to be called the GP22, following the previous designations based on horsepower. But to add competition to GE's U25B, EMD changed the designation to GP30, saying it had "30 improvements".

I don't know exactly why EMD chose GP35 for their next model designation, but most likely it was for competitive reasons, again, saying it either had '5 improvements' or '35 improvements' over the GP30.

Some more prefixes for EMD...
P- Passenger
PH- Passenger w/Headend power
A- cab unit (F7A)
B- booster unit(F7B)
DD- 8-axle trucks
F- cowl body
L- Lightweight frame
C- 6-axle trucks (F40C)
T- Tunnel Motor
S- Short frame
X- Experimental

E.M. Bell
07-13-2004, 12:19 AM
and lets not forget the BL2 (BL= Branch line) and the very very rare EMD model 40....a 44 tonner on steroids...

and the F series was just not passenger units...the where multi-purpose...including the most popular, the FP7...

07-13-2004, 02:16 AM
Well, you might as well throw in the C&EI RS 1325 then!

Here's a site that lays out the models. Don't know who complied the data but it looks pretty complete.


07-14-2004, 03:34 AM
Thanks for all the replies; that helps.

In the meantime, I'll be along the rails in my Nissan BAL245M (for you uninformed, that's a 4-axle, 245 hp, comfort cab Nissan Altima) :lol:

07-16-2004, 02:30 AM
Your Altima has 6 axles? I'd like to see those modifications! Is it a -2? :lol:

07-16-2004, 05:19 AM
Your Altima has 6 axles? I'd like to see those modifications! Is it a -2? :lol:

Ha! Not 6, but you can check it out in my latest photo; it has a cameo on the right side of the frame!