The GE; General Electric, AC4400CW is a high-powered six-axle, AC-traction 4,400hp diesel locomotive built from 1995 to 2004 (first introduced in 1994), and is also one of the very first high-powered, single-engined, AC-traction diesel locomotives produced by GE, as well as being one of the very first major types of commercially successful North American AC-traction diesel locomotives ever built (besides the EMD SD70MAC; its EMD Equivalent).
Many still exist and are still currently in service with various railways and railroads throughout North America, as well as various places in Latin America and Australia.
The AC4400CW is simply the AC-powered version of a GE C44-9CW or "Dash 9", which is a type of DC-traction diesel locomotve, yet it was one of the first GE diesel locomotives to have an advanced microprocessor control system (better than what was offered or featured with the Dash 8 and Dash 9) and wasn't even considered to be part of the Dash 9 line from GE. The AC4400CW was first built and demonstrated in 1994 and succeeded in dominating over the EMD SD70MAC a year later, to which the AC4400CW was built to compete with. EMD's SD70MAC was one of the very first major types of pure AC-traction North American diesel locomotives hence, the AC4400CW being GE's response to the EMD SD70MAC; thus, creating their own type of revolutionary AC-traction diesel locomotive and dominating over the competition.
The type or model was originally built to serve the Chicago And Northwestern (CNW) and Union Pacific's (UP) coal drag service on their rather long and heavy coal trains across Wyoming in the Powder River Basin. Though originally intended and used for such, both railroads (even during the time of the merger between the UP and CNW in 1995) eventually used their fleets of "pigs" on other general revenue freight trains as with how CP, CSX, and other owners use their units as of today; thus, making the AC4400CW more of a "horse" than a "pig" (as referred to by enthusiasts, considering that AC4400CW units were intended for slow "pig" service as opposed to high-speed "horse" service).
The AC4400CW was also one of the first diesel locomotives to be equipped with self-steering "steerable trucks" (which were first offered with the AC4400CW's DC-traction counter-part: the C44-9W, besides first being invented or introduced with the AC4400CW's competition: EMD's SD70MAC; previously on the preceeding SD60MAC) and to be capable of providing "distributed power" to serve as a "distributed power unit" (DPU); which is a form or technique of having multiple locomotives placed on different parts of a train, operate on the same train, and to be controlled by the engineer of a leading locomotive simultaneously without the need of having multiple crews operate multiple locomotive sets at different speeds on different parts of a train. The type of locomotive also included "controlled tractive effort" (CTE), which helped provide better tractive effort for whenever a wheelslip were to occur; similar to what was originally included with EMD's SD80MAC. Although DPU and CTE technology proved reliable on earlier AC4400CW units, the CTE technology had a tendency to fail; thus, a new type of truck or bogey was developed later-on during production, hence providing even better tractive effort; yet was only popular with Ferromex (FXE), CSX, and CP Rail (Canadian Pacific) who were some of the several customers to order both styles or versions of trucks for their AC4400CW fleets.
Several US and Canadian Class 1 railroads (such as the Union Pacific, Southern Pacific, CSX, and the Chicago And Northwestern (aside from Ferromex and numerous Mexican Class 2 railways or railroads in Mexico) purchased the AC4400CW because of how reliable it was (and still currently is) with long and heavy trains up steep grades or slopes, as well as having advanced microprocessor controls and DPU capabilities (as seen in the article).
Many are still currently in revenue service, though several have been scrapped as a result of being involved in wrecks. It's initial success further led to the development of the AC6000CW.
The AC4400CW shouldn't be confused with its DC predecessor (C44-9W or the "Dash 9").
One notable difference is the style of trucks or bogies, which are usually placed on either, or both sides of the locomotive; while another difference is that a large radiator cabinet cover is placed on one side of the locomotive.
Another notable difference, is the fact that some U.S Class 1 railroads (aside from Mexican and Canadian) often paint lightning bolts on the sides of the cab or radiator.
- GE originally planned on having the AC4400CW to have completely different appearance from the Dash 9, but decided not to as a result of design interference.
- The SD70MAC was chosen over the AC4400CW by Burlington Northern, due to the SD70MAC being somewhat more affordable and had a better performance during its introduction (besides having more successful demonstrations with the BN as a result of the SD60MAC experiment).
- The distinct 'lightning bolts' are more commonly painted on CSX's AC-powered or AC-traction EMD SD70 series units rather than AC4400CW units because of the noticeable truck variant (though, all AC-traction units have such distinction; minus a handful of AC6000CW units). The UP (at one time) used such distinct method, yet because of UP primarily using AC-traction diesel locomotives as of today, the lightning bolt outline style of their "Armor Yellow" scheme is simply just a mere variant nowadays. (Same with the CNW's lightning bolt scheme, which was also merely a denontation of the "new millennium"; yet the CNW became defunct 5 years short of the year 2000.)
- The Chicago and Northwestern (CNW), Southern Pacific (SP), and CSX were the first railroads to purchase the early version of the AC4400CW without the distinguished trucks, yet they had small "humps" in between the gaps which were originally used for roller bearings.
- CNW's fleet of AC4400CW units were the first to receive DPU and CTE technology, which wasn't even included with the UP or SP's orders.
- The AC4400CW was also one of the last types of locomotives owned by the SP and CNW before the UP's purchase of both railroads in 1995 and 1996, besides also being one of the only types of diesel locomotives owned by either railroad to have AC-traction.
- Most of Union Pacific's AC4400CW's are actually former SP and CNW AC4400CW's, to which their original fleet was tiny compared to after the purchase of both the CNW and SP.
- The majority of AC4400CW's owned by the CNW sponsored the Operation Lifesaver campaign.
- AC4400CW locomotives without the distinguished 'AC trucks' are often referred to as the AH4400CW, AC4400CCTE, or the C44CCTE, as well as the AC44ACCTE, AC45ACCTE (the '5' meaning the truck length) AC44CCTE or C44CCTE as well as the names also being the DC to AC conversion name.
- As of 2012, all of UP's former CNW and SP AC4400CW units are also converted from their DC counter-part (Dash 9's; thus becoming AC45CCTE's) which is what the CNW and SP originally ordered before GE introduced the AC4400CW.
- UP AC4400CW #9700 (originally a C44-9W) was the very first AC4400CW (or Dash 9) ordered by Union Pacific in 1994, and was actually one of the many converted from a Dash 9. The unit was also rewarded with a safety award, yet it; however, was placed in storage and was neglected for several years.
- Several SP AC4400CW units remain unpatched; 309, 319, 335, 343, and 352.
- AVWR numbers 767 and 777 were two former CP AC4400CWs used for the fictional "Unstoppable" film back in 2009/2010 (as of late-2010, the units still wear the stripes applied to the plows on the unit's fronts).
- The AC4400CW prototype had Dash 7-style trucks before hi-aid and AC hi-aid trucks were developed for the official production model.
- A Brazilian or Latin American variant exists as well; the AC44CWi.
- UP #6700 (formally 9997, the other two being 9998 and 9999) was the very first official of the three AC4400CW units purchased by the Union Pacific (excluding their Dash 9's).
- Oddly, UP #6289 (a former SP AC4400CW) was patched with a flame-style decal as opposed to the usual patchwork.
- Several numerous GECX (General Electric Company Leasing) AC4400CW demonstrator units were actually painted in UP primer livery in 1997 before eventually becoming part of a preposed order from the railroad (one in particular; #7001, still retains primer livery as of early-2013.
- CNW #8801 (now UP #6703) was the very first ever AC4400CW unit delivered to any North American Class 1 railroad (though, specifically for the CNW) and also received a special commemorative plaque regarding a deceased train operator from Bill, Wyoming (where most of the CNW's AC4400CW units originally operated and still do as of today) and has also received an unusual amount of patchwork in recent years.
- Ironically, the very first CNW unit to be repainted and renumbered into the UP was actually involved in a serious wreck during a head-on collision on a blind curve on the UP's Donner Pass route in Northern California sometime turing 1997-1998; nearly completely destroying the locomotive. Thankfully, the unit was salvagable and has since been rebuilt back to its original shape.
- CP #8644 was the first of several AC4400CW units to be retired.
- CSX #1 "Spirit of West Virginia" originally didn't retain such banner, and received it during an overhaul which resulted in the replacement of the original "hi-aid" trucks with the once-exclusive "AC trucks".