Bio Edit

Most modern, diesel-electric locomotives manufactured by EMD (beginning with the GP30) are often hard to distinguish from one another, and often have parts or components which are hard to identify.
EMD Diagram

A detailed diagram of a BN SD40-2ECO: an early LNG (light natural gas) demonstrator, which has distinct flared radiators like that of an SD45.

Average, modern, standard-cab models consist of these traits (namely 2nd generation and early 3rd generation ones):


  1. Hood: Or "nose"; can be seen on every "A unit".
  2. Cab: Houses the crew and the operating equipment or controls to power and activate the locomotive (though, engine starters are usually located within the access panel doors on the long hood).
  3. Central Air Intake: Draws in air for the engine, and also draws air to pressurize the engine bay (engine compartment). Exhaust vent is typically mounted in the middle between numbers 3 and 4.
  4. Roof-top Fans: Center two fans are utilized for the dynamic brake grid section, while the rear three fans are meant for drawing air through the engine radiators to cool the engine (from the cool air sucked in through the air intakes). The hot air is then vented through the fans upward.
    WM GP9

    A Western Maryland (WM) "chop nose" GP9 revealing the dynamic brake grid section featuring the distinct grilles (the rooftop fan isn't visible, but is present). Models like the GP9 are often regarded as "1st generation" diesels produced by EMD, but have many notable features present on later models.

  5. Radiator Vents: Or air intake vents, which are used for drawing in or sucking in cool air to eliminate heat from the engine bay located within the interior of the main carbody, or center of the long hood.
  6. Trucks (bogeys): Frames which include or consist of the wheels, axles, and traction motors.
  7. Blower Duct: used for blowing cool air to the traction motors (and in some cases, the turbocharger or roots blower depending on the configuration of the interior cooling systems).
  8. Dynamic Brake Grilles: Intakes utilized for cooling air for the dynamic brake rheostats. Exists if dynamic brakes are fitted.
  9. Cab Door: Used by crew members for accessing the cab (door shown is the front door, while a back or rear door is located on the rear of the engineer's side of the cab).
  10. External Handbrake: Placed on the side of the short hood. Used for holding the locomotive when stopped or stored. In this instance a ratchet system, but is often found as a wheel type. This was moved near to the end of the long hood when Safety Cabs were introduced beginning with the SD60M.
    SD50 Diagram

    A diagram example of an ex-SP (nee DRGW) SD50.

  11. Brake Cylinders: Used for storing pressurized air, and are connected to the brake pistons and shoes.
  12. Fuel Tank: Houses fuel for the locomotive (bell is usually located in front of right-side fuel tank as observed closely in the image shown above).
  13. Air Tanks: Mounted on both sides above the fuel tank; used for storing pressurized air for the brake cylinders, and commonly acts as the "brain", while the interior brake levers mounted on the control stand(s) serve as the "nerves".


  1. Blower Duct
  2. Exhaust Vent
  3. Dynamic Brake Grid: Consisting of vents or grilles (mounted below the opposing upper ones), a radiator fan, and acess panels or side doors.
  4. Brake Wheel (external handbrake)


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