From: 737ochs@gw.wmich.edu
Newsgroups: rec.models.railroad
Subject: Re: All about Diesels (LONG!)
Date: 19 Nov 92 02:54:15 EST
Organization: Western Michigan University

In article <BxxpBL.LC4@access.digex.com>, car@access.digex.com (Mr. Blue) writes:
> I am trying to gain some very basic knowledge about diesel engines so
> that I can buy the models with some intelligence. Could someone give me
> the basic rundown of the different classes of diesel engines and what they
> were used for?

OK, I'll try it!
To begin with, EMD stands for Electro-Motive Division of General Motors,
GE is General Electric, Alco is Americal Locomotive Works,
Baldwin is Baldwin Locomotive Works, Lima is Lima-Hamilton
BLH is Baldwin,Lima,Hamilton, MLW is Montreal Locomotive Works,
FM is Fairbanks-Morse, and there were a few other small ones.
Only EMD and GE are still producing railroad locomotives

EMD's first main model was the FT which I'm sure stood for freight
It had 1350 HP(horse power) They were designed to be semi-permanently
coupled and sold usually as sets. They came in both A and B.
An A unit is one with a cab and controls, a B unit is an engine without
a cab, or with a cab with the controls removed
This was followed by the following engines:
F2A,F2B 1350HP
F3A,F3B,F7A,F7B 1500HP
F9A,F9B 1750 HP
These are all cab units (no walkways, and the outer shell is built as part
of the frame, to give it strength)
They also had B trucks, which means that they had 2 axles on each truck
each with a traction motor (which drives the axle using electricity from
the generator)
We also have the E unit, which is like the F unit, except it has 3 axle
trucks, called A1A since the center axle is not powered
They also have 2 engines in them, to give them more HP.
Here are the models:
EA,EB,E1A,E1B,E2A,E2B 1800HP
E3A,E3B,E4A,E4B,E5A,E5B,E6A,E6B,E7A,E7B 2000HP
E8A,E8B 2250 HP
E9A,E9B 2400 HP
These also are cab unit style.
The model number on both of these changed usually when EMD made a change.
Either externally or internally.

Before making the F7, EMD introduced a new model type, called the BL1
It stood for Branch Line, had 1500 HP, and had the same motor that the F7
and GP7 (which I will explain) did.
They followed this by the BL2, although it is argued what the change was.
This engine had most of the cab style, with notches along each side, that
would allow the engineer to see behind him better.
This was followed by the GP7 (and concurrently produced with the F7)
The GP series stood for General Purpose, and had walkways along each hood.
It camein both passenger and freight versions. Passenger versions had a
steam generator in the short hood (typically called the nose) to heat the
passenger cars. This engine had B trucks and 1500 HP
here is a list of GP style engines:
GP7 1500 HP
GP9 1750 HP
GP15 1500 HP
GP18 1800 HP
GP20 2000 HP
GP28 2000 HP
GP30 2250 HP
GP35 2500 HP
GP38 2000 HP
GP39 2300 HP
GP40 3000 HP
GP40X 3500 HP
GP50 3500/3600 HP
GP60 3800 HP

The current model EMD builds is the GP60.
The next frieght style is the SD series, which stands for Special Duty.
These have C trucks, instead of B trucks, and are typically a lot heavier
then their GP counter part. here is a list of their models:
SD7 1500 HP
SD9 1750 HP
SD18 1800 HP
SD24 2400 HP
SD28 2000 HP
SD35 2500 HP
SD38 2000 HP
SD39 2300 HP
SD40 3000 HP
SD45 3600 HP
SD45X 4200 HP
SD50 3500/3600 HP
SD60 3800 HP
SD70 4000 HP
The SD 60 is the current model, the SD70 is the next model they are introducing
They have built 2 demonstrators, and one railroad has ordered 4 of them (Norfilk
Southern). 
Most of these were freight, bu they could be bought with steam generators
(usually located in the short hood) for passenger service. EMD also produced
a couple with the steam generator in the rear, these are the following models:
SDP40, SDP45, also included are the GP40P and GP40TC which are 2 axle but
had steam generators in the rear
Then thereis the later F series, which was basically like the GP and SD,
but had cowling over the engine, instead of walkways. This cowling is not
part of the structural support, like the earlier F series.
These engines include:
F40PH 3000 HP <-standard Amtrak engine everyone knows and loves :)
F45, FP45 3600 HP (the FP had a steam generator in it)
We also have the SD40F,SD50F and SD60F which are SD40,SD50/SD60's 
with cowling over them instead of walkways. Bought by Canadian RR's.
Now to the switchers, another long list!
A switcher is typically, small, lightweight, and has a cab at one end,
and no nose, instead it usually has large windows for visibility.
EMD started out with the NC which had 900 HP, and was experimental.
then followed with the following models:
SC,SW 600 HP (SC stood for cast frame, SW stood for welded frame)
NC, NC1, NC2, NW, NW1, NW1A 900 HP (again, c for cast w for welded)
also s stood for 600 and n stood for 900, but that was changed later
NW2,NW4 900 HP
SW1 600 HP
NW3,NW5 1000 HP
SW8 800 HP
SW600 600 HP
SW900 900 HP
SW7 700 HP
SW9,SW1200 1200 HP
SW1000,SW1001 1000 HP
SW1500, MP15 1500 HP <- the MP stands for Multi Purpose, still looks like
                        a switcher though, and is the current production model
The other odd model EMD produced was the DD series, which had DD trucks
(4 axles, 4 traction motors per truck)
These were double ended diesels, and were roughly like 2 engines put together
in one. They had the following:
DD35A,DD35B 5000 HP
DDA40X 6600 HP
Only Union Pacific had the DDA40X and the DD35A.
Both UP and Southern Pacific had the DD35B

GE's is a bit easier to describe. They started with the U series, which
stood for Universal. They are either B or C, depending on whether they
had B trucks or C trucks. The U series had the following models:
All GE models use their HP in hundreds as part of the model designation,
along with the type of trucks and the engine series.
U18B 1800 HP
U23B,U23C 2250 HP
U25B,U25C 2500 HP
U28B,U28C 2800 HP
U30B,U30C 3000 HP
U33B,U33C 3300 HP
U36B,U36C 3600 HP
There was also a U50 and U50C which was a double U25, with either 2 sets of
B trucks on a span bolster (U50) or on C trucks (U50C)
Sometime in the late 70's (1977 I think) they dropped the U series, and
went to the -7 series, all models produced there after looked like this:
B23-7,C23-7 2300 HP
B30-7,C30-7 3000 HP
B36-7,C36-7 3600 HP
I dont believe they carried the U33 into the -7 line
in the mid 80's (around 1984) they dropped the -7 line and went to the -8
line, which is the current production line. These are the following models
so far:
B32-8,C32-8 3200 HP
B36-8,C36-8 3600 HP
B38-8,C39-8 3900 HP
B40-8.C40-8 4000 HP
the B40-8 and C40-8 are the current model in production.
They have also flipped the designation to DASH-8 40B and DASH-8 40C
Although many railroads retain the other designation

There is also a modification on the current production of engines,
that being a cowl (like described before) or a safety cab.
For EMD's the wide nose is designated by adding an M after the model name
(like SD60M or GP60M) on GE is is a W, (Like CW40-8,DASH-8 40BW)
They also have the full width cowl with a W (DASH 8-40CW) bought only
by Canadian National and BC Rail (British Columbia Railway)

Most of this information is in the _Second Diesel Spotters Guide_ or
_Diesel Spotters Update_ 
I wont go into the other RR's, since Im not rewriting their books,
but this gives you a general description of the two most prominent
Locomotive makers. GE currently is producing more than EMD, EMD had been
on top since the beginning(of mass-produced diesel locomotives)

Hope this helps ya!
If you have any questions, feel free to shoot them to me
Fred Ochs
737ochs@gw.wmich.edu (VAX)
ochs@sol.cs.wmich.edu (UNIX)
Newsgroups: rec.models.railroad