SD59MX No. 9926 at Davis, California in 2017.

By Pi.1415926535 - Own work, CC BY-SA 3.0,

EMD SD32ECO Diesel-Electric Locomotive
The EMD SD32ECO is a 3,150 hp (2,350 kW) C-C diesel-electric locomotive rebuilt by Electro-Motive Diesel. It is primarily the application of a conversion kit to an existing EMD SD60-type locomotive. This involves replacing the existing 710G3A V16 prime mover with an EPA Tier-II-compliant 710G3B-T2 turbocharged V12, with Electronic fuel injection. Many of the donor SD60's major components and subsystems are recycled and are recertified as equal to new. However, the locomotive's control system is all new.

At least 24 Union Pacific SD60Ms have been scheduled to be sent to EMD for this rebuild and a number have been returned by EMD and are already in revenue service. So far, all converted locomotives have been of the later "two window" cab type, not the earlier "three-window" cab type. SD59MX is the Union Pacific designation for this type.

BNSF has sent 3 SD45-2 locomotives to be rebuilt as SD32ECOs. Unlike UP's SD59MX, BNSF's SD32ECOs retain the appearance of an SD45-2. So far, 3 have been ordered, and will be numbered 1350-1352.

The SD59MX is remanufactured from the carbody and major mechanical and electrical subsystems of an EMD SD60M "donor". The EFI-equipped 710 engine, however, is all new as are the engine and locomotive control systems. Union Pacific is the first Class I railroad to order them. The engine control system is adaptable to both minimum emissions and minimum fuel consumption modes, depending upon their assignment.

The EMD SD59M-2, more commonly referred to as the SD59MX, is one of the rarest locomotives in the Union Pacific motive power fleet. SD59M-2s are remanufactured SD60Ms.

Spotting features:
  Wide-nose, so far only the later two-window wide nose rather than the earlier three-window "tri-clops" wide nose and none of the traditional 40 Series cab SD60s have been converted.
  Slightly slanted radiator air intakes.
  High-adhesion HT-C trucks, reused from the "donor" SD60M, rather than the newer "radial" or "bolsterless" trucks. Nearly all SD40-2s and SD50s used the same truck.
  Safety fuel tank like that found on current SD70Ms.

The external appearance of the converted locomotive is sometimes altered by application of a flared radiator section, similar to the SD70M-2 and SD70ACe Tier-II, and similar to late model SD70M and SD70MAC locomotives in appearance. The recently converted locomotives (including UP 9905 and 9906, seen recently at the CSRM; and others up to at least UP 9924) have also had the SD70M-2/SD70ACe-style safety fuel tanks applied.

Advertised benefits
Advertised benefits include:

  EPA Tier-II compliance.
  Fuel savings up to 25%.
  Lube oil savings up to 50%.
  Upgradeable software can be tuned for reduced emissions or improved fuel efficiency.
  Microprocessor control offers diagnostics, wheel slip control, and optimal wheel/rail adhesion.
  184-day maintenance cycle instead of 92-day.
  15,000 MWh overhaul cycle.
  Reduced maintenance expense due to use of standard 710 prime mover.
  Automatic Engine Start Stop system keeps locomotive ready without wasting fuel.

EMD SD32ECO Overview
Type and origin
Power type: Diesel-electric
Builder: Electro-Motive Diesel (EMD)
​ • AAR C-C
Gauge: 4 ft 8 1⁄2 in (1,435 mm)
Prime mover: EMD 12–710G3B–T2
Cylinders: V12
Performance figures
Power output: 3,150 hp (2,350 kW)

See also:

EMD Diesel-Electric Locomotives

Electro Motive Diesel

Union Pacific

Diesel-Electric Locomotives


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SD59MX No. 9926 at Davis, California in 2017.
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