What does this mean. All the AC4400CW's have it as do the new ES44AC's. The SD40-2'S and the Geeps have different numbers, but same question to those also.

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A BNSF fan by default.

I believe it means:

D = Diesel
R = Road
F = Freight
44 = 4400 horses

Hence the other units would have different numbers depending on the horse power. The old Milwaukee Road did a similar thing.

Basically, I think it is the particular railroad's way of classing the units in their system for horsepower calculation when building a train. An example would be the SD40-2: it is 3000 horsepower, but nothing in the EMD model designation tells you that. So the railroad assigns or classes it as DRF-30. So everyone knows that it is a 3000 horse diesel unit, designed for the road versus the yard, with freight speed rating. Makes it quicker and easier to build a multiple consist that requires 12000 horsepower.

Makes sense, similar to the UP having to change the classifications of every loco also.

_________________
A BNSF fan by default.

I should have pointed out the Milwaukee's system was slightly different.

An example of theirs is:

23-ERS-6

23 = 2300 horses
E = Electrical
R = Road
S = Switcher
6 = 6 powered axles

or a GP9 was 17.5-ERS

An MP15 was 15-ES (no R, as it was basically designed for yard operation)

They seemed left off the 4 for the axles on many SW and GP units for some reason