Locomotive Wiki

EMD; Electro Motive Division, first established numerous prefix and suffix designations during the early years of their establishment as the EMC Corporation (before the GM purchase in 1937; excluding the CAT purchase in 2012, to which the name never changed other than "Division" being altered to "Diesel"). They initially began designating their various types of diesel locomotives as follows:

Early (Pre-EMD) Prefix Meanings[]

BL - "Branchline"

E - Originally meant "eighteen hundred horsepower", it is the designation of all EMD 6-axle cab units.

F - Originally meant "fourteen hundred horsepower", it is the designation of all EMD 4-axle cab units.

FT - Cab unit; fourteen hundred horsepower

FP - Passenger service (equipped with a steam generator; unlike later types long after the GM purchase)

NC - Nine hundred horsepower; cast frame

NW - Nine hundred horsepower; welded frame (though, the term as eventually used for classifying

SW - Six hundred horsepower; welded frame (though, eventually designated as "switcher" from 1937-onwards)

T - "Transfer"

Later (1937-onwards) Prefix Meanings[]

DD - Eight-axle locomotive with 'D' trucks (or "Double Diesel")

F - Cowl locomotive (protective carbody; like on the F45)

GP - "General Purpose"; road switcher with B-B axle arrangement

SD - "Super Duty" (or "Special Duty"); road switcher with C-C axle arrangement

P - "Passenger" (such as with the GP40P-2)

RS - "Road Switcher" (as in RS1325; though the designation was originally used with ALCO for their "RS" series)

SW - "Switcher" (as seen above)

Suffix Meaning[]

A - Cab unit (locomotive with cab and controls)

AC - Alternating current electrical systems (such as with the SD70MAC and/or GP38AC)

B - "Booster" unit (cabless locomotive without cab and controls)

C - For C-C (six-axle trucks); though the designation is often implied for use on Canadian rebuilds/versions of production EMD diesels (such as the F40PH-3C)

F - Cowl/cab locomotive (protective carbody; as mentioned)

I - "Isolated cab" (as with the SD70I and subsequent "isolated" variants of the SD70 without the "I" designation)

M - "Safety Cab" (or "modified"; as with the SD60M and SD70M; minus the "AC" suffixes as evident with the SD60MAC and SD70MAC)

PH - Passenger locomotive with head-end power (HEP; as with the F40PH, though earlier models were originally fitted with steam generators)

T - "Tunnel" (for the "Tunnel Motor" series consisting of having locomotives with large air intakes located on the running boards or sides of the carbody as part of an advanced cooling system; such as with the SD40T-2)

35 - Number of series (such as the SD45, GP35, F7, etc.)

Other Prefixes[]

MP - "Multi-purpose" (as in the MP15 series)

Other Suffixes[]

e - "Enhanced" ("energy-efficient" or "eco-friendly" as implied with the SD70ACe)

T - "Turbo" or "Turbocharged" (like with EMD's MP15T built specially for CSX)