Shout out to Kaylee Zheng whose clinic was the initial data for this cheat sheet!
EMD Model Designation
Example: SD70AC
Unit Type
Locomotive Series
Improvement Series
Options/Modifiers
F = Cowl/Monocogue Unit SW = Switcher MP = Multi Purpose Switcher GP = General Purpose (4 axle) SD = Special Duty (6 axle)
If last digit is 9, then 12 cylinder prime mover; otherwise 16 cylinder.
Exception: T4 locos are 12 cylinders always
(blank) = base version
-1 = EMD reman. program (late 1960s)
-2 EMD reliability improvement series
A = Special Custom Builds AC = Alternator or AC Traction M or W = Wide cab I = Isolated (vibration reducing wide cab) L = Lightweight frame P = Passenger/steam heat H = Head End Power (HEP) e = Reduced emissions compliant -T4 = Tier 4 emissions compliant IAC = Individual Axle Control P4 [?] = B1-1B wheel arrangement X = Experimental
GE Model Designation
Example: Dash944CW
Locomotive Series
Locomotive HO x 100
Wheel Arrangement per Truck
Options/Modifiers
U = Universal P = Passenger Dash8 = Dash 8 Series Dash9 = Dash 9 Series AC = AC Traction Series ES = Evolation Series ET = Evolution Series, T4 Compliant
For AC series, full HP is written out, although, conventional 2 digit HP indicator is also used interchangeably
C = Cowl Unit H = Head End Power (HEP) P = Passenger Q = Extended Crew Cab W = Wide Cab
Round One:
Roof Line: Clean
Roof Line: Congested
Fuel Tank: Angular
Fuel Tank: Rounded
Brake Reservoir: Two tanks
Brake Reservoir: Long "Torpedo Tube"
Exhaust stack right before radiator
Exhaust stack towards cab
GE
EMD
Round Two:
Radiator "winged" (except U-boats)
GEVO has mini-radiator in front of main radiator
GEVO T-4 similar to standard GEVO radiator but massive
Radiator has raised fans:
Two large fans - 38 series
Three large fans - 40 series
Three large fans, angled radiator - 45 series
Three large fans, tall radiator screens - 50/60 series
Three large fans, tall angled radiator - 70 series
Three large fans, chunky angled radiator - 80/90 series
Two XL fans, chunky angled radiator - 80/90 series (Ace)
Three XL fans, chunky angled radiator - 80/90 series (Ace T-4)