QUOTE: Originally posted by M636C The Dash9-44CW and the AC4400CW are DC motor and AC motor versions of the same locomotive. The "Dash9" has an air conditioner behind the cab on the left side and the main DC electrical switchgear under the cab. The AC4400CW has the AC inverters behind the cab on the left side (in a bigger box than the air conditioner on the Dash9) and the air conditioner is moved under the cab (into the space left by the DC equipment). The AC4400CW also has one more dynamic brake vent in the "hump" in the hood behind the cab. The ES series have a new "GEVO" twelve cylinder engine that is as powerful as the sixteen cylinder FDL engine in the Dash9. This has a new feature, the "air to air intercooler" which cools the air after passing through the turbocharger before it enters the engine. (The older GE units all used water cooled intercoolers, which cooled the water in the ordinary radiators). The air to air system is more efficient but needs wo extra small fans just ahead of the radiator in a box that matches the shape of the radiator, giving the appearance of a bigger radiator. This radiator change is the main appearance difference in the ES series from the earlier units. GE call the new units ES44AC (replacing AC4400CW) and ES44DC (replacing Dash9-44CW). NS reduce the power of their units from 4400HP to 4000HP, so they call their units ES40DC. So far other roads do not do this, so if BNSF buy DC units, they would be ES44DC. Peter
QUOTE: Originally posted by 4884bigboy There are really no phsycial differences between these locomotives. I know the GEVO (ES40DC) has a square rear end, but otherwise they all look pretty much the same.