TheIndian locomotive class WDG-4 (EMD GT46MAC)is a type of six-axle (Co-Co)freight-haulingdiesel-electric locomotivewith AC electric transmission designed byGeneral Motors Electro-Motive Diesel[1]in 1997–1998 forIndian Railways,where they are classed asWDG-4.Derived from theEMD SD70MAC,it is powered by a 4,000hp(3,000kW)16-cylinderEMD 710G3Bprime mover. Thirteen were built by EMD as order #958647, and a further eight were exported in kit form and assembled in India. The class entered service in 1999. A Dedicated Passenger version of this locomotive, theWDP-4(EMD GT46PAC), has also been produced, with a Bo1-1Bo Wheel Configuration, which entered service in 2001. These locomotives are also famous for, and can be identified, by the distinct and uniqueJet Plane-like sounding capability of the EMD 710 prime mover.
Further construction has been under license in India by theBanaras Locomotive Works (BLW),with the first purely indigenously built WDG-4 locomotive, numbered 12022, that rolled out in 2002. More than 60 additional locomotives have been built as of 2006[update].They are numbered from #12001 upward.
As of August 2007[update],EMD and DLW have begun building GT46ACe's usingIGBTtechnology to replace the oldergate turn-off thyristortechnology and along with increase of 500 hp, ie, 4,500 hp (3.4 MW), using the Newly tweaked EMD 16N-710G3B-EC, like the passengerWDP-4Bhave been produced. Newer versions with widenedPiggy-facecab profile for enhanced visibility, just like the later variants of WDP-4's and WDP-4B's were also produced.
As of February 2013[update],DLW began building the Dual Cab version, EMD JT46ACe, calledWDG-4D,based on the passenger variantWDP-4Dlocos, same for both-side visibility. Here again, many features, including IGBT and 4,500 hp have been carried on from the single cab GT46ACe's. The first WDG-4D, numbered 12681, is named "Vijay". Later WDG-4D's were numbered from 70301, as the 12*** series came to an end in 2014 and got switched to 70*** series. Over 1,500 such locomotives, including both WDG-4's and WDG-4D's are currently in operation.
Indian Railways has also developed the WDG-4 series intoEMD GT50AC(aka WDG-5), using a v20-710G prime mover, based on theSD80MAC,rated at 5,500 HP (4,130 kW). However, this locomotive has turned out to be a Failure, due to various reasons.
Since the year 2017, BLW (DLW then) began manufacturing such locomotives for Non-Railway Customers. The first such locomotive, which would be a Dual-Cab WDG-4D, rolled out to serveOdisha Power Generation Corporation(OPGC), in March 2017. 3 WDG-4D locomotives currently serve OPGC. As of 2024, 2 new Single-CabPiggy-faceWDG-4 locomotives have been manufactured and rolled out forObra Thermal Power Station,based at Sonbhadra, Uttar Pradesh.