The ET44AC (Evolution Series Tier 4, 4400 HP, AC traction) replaces the ES44AC model. These locomotives have been ordered by most of the Class I railroads in North America, including Union Pacific, CSX Transportation, Norfolk Southern, KCS, and Canadian National Railway. BNSF Railway will be receiving similar ET44C4 locomotives, which have no traction motor on the middle axle of each truck. In the summer of 2012, GE unveiled its first Tier 4 emissions-compliant locomotive, now officially named the ET44AC. The prototype demonstrators, as well as current production units, are visually quite different from previous models. First, the “ET” is 74 feet 6 inches (22.71 m) long – an increase of 16 inches (0.41 m) from the 73-foot-2-inch (22.30 m) length of all previous GE 6-axle models beginning with the “DASH 9” series in 1993. While the front third of the locomotive, including the control cab, is basically unchanged, the rear two-thirds is noticeably different. On Tier 4 demonstrator units the entire midsection above the prime mover is raised to accommodate an advanced exhaust treatment system; it is seen as a “hump” that rises above the rest of the locomotive considerably. Production units have this hump only over the exhaust manifold directly ahead of the radiator, rather than encompassing the entire midsection. In addition, the radiator section is much larger than that of earlier “ES” units, featuring a two-fan split-cooling system located inside a very large, angular compartment. Grilles under the radiator section have been smoothed out, and there are two extra air intakes on the rear of the locomotive hood. ET44ACs are all equipped with Graham-White electronic bells (E-bells). Tier 4 demonstrator units are equipped with two airhorns: a three-chime horn – facing forward – located behind the cab and a rear-facing two-chime horn protruding from the back of the radiator. Production units feature the now-standard Nathan-Airchime model K5HL-R2 “Evolution” air horn mounted on the hood slightly forward of the placement location used on previous models. A DC variant of the ET44AC has not been cataloged by General Electric, as railroads prefer AC traction units.

The ET44AC, along with the ET44C4, was General Electric’s final production road-switcher before the transportation division was sold to Wabtec Freight in 2019.

This particular model was part of its Evolution Series, a stand alone variant aimed at meeting the Environmental Projection Agency’s latest Tier IV emissions standards that went into affect on January 1, 2015.

GE had been successful in adapting its previous ES44AC to meet EPA’s Tier III standards (January 1, 2012).  This same locomotive was revolutionary when it debuted in 2003 to meet EPA’s then Tier II standards (January 1, 2005). 

While the company’s new GEVO prime mover was up to the challenge, GE was still forced to make changes in meeting Tier IV demands.  In addition, engineers had to redesign other aspects of the locomotive’s radiator and internal components.

To date, there have been a few hundred examples of the ET44AC produced since it debuted in 2015.  As of this writing Canadian National, CSX, Norfolk Southern, and Union Pacific have all purchased the model.

In addition, BNSF has acquired more than 200 examples of the ET44C4, the A1A-A1A variant first introduced in 2009 as the ES44C4.

For sharp-eyed railfans, the most noticeable difference between the ES44AC and ET44AC includes:

A larger rear flared radiator with a pronounced “V” appearance.

Inclusion of the horns just above the cab as well inset within the radiator at the rear.  These had previously been located at the center of the car body in one grouping, but GE needed this space for additional components.The overall height of the cab was increased to 16 feet, 1 inch.  As such, the ET44AC has reached its maximum possible height and still meet clearance restrictions, such as tunnels and overpasses.

With Wabtec Freight acquiring General Electric’s transportation division in early 2019, the future of not only the locomotive production market but also that of GE-designed products is interesting.

GE had nearly limitless resources in developing technologically advanced models that had far surpassed EMD by the 1990s, such as the AC4400CW and C44-9W.

This continued with the Evolution Series in the early 2000s.  It will be fascinating to see how Wabtec Freight navigates the locomotive market moving forward.

The ET44C4 was introduced alongside the ET44AC and to date, only BNSF has acquired the model.  It was a return of the A1A-A1A wheel arrangement whereby the center axle is unpowered.

General Electric had first reintroduced the concept in the earlier ES44C4.  BNSF was also the only buyer but wound up with some 1,137 examples.

What the company dubbed its Dynamic Weight Management System, Mr. McDonnell’s book notes that “the computer redistributes the load from the unpowered center axles onto the powered 1, 3, 4, and 6 axles as demand warrants.”

Links:

https://www.american-rails.com/et44ac.html

https://locomotive.fandom.com/wiki/General_Electric_ET44AC

https://www.wabteccorp.com/locomotive/heavy-haul-locomotives/et44ac-locomotive