Indian locomotive class WDG-4

The Indian locomotive class WDG-4 (EMD GT46MAC) is a type of six-axle (Co-Co) freight-hauling diesel–electric locomotive with AC electric transmission designed by General Motors Electro-Motive Diesel^[1] in 1997–1998 for Indian Railways, where they are classed as WDG-4. Derived from the EMD SD70MAC, it is powered by a 4,000 hp (3,000 kW) 16-cylinder EMD 710G3B prime 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, the WDP-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 jet-airplane–like sound of the EMD 710 prime mover.

WDG-4
A three WDG-4s standing at Castle Rock.
Type and origin Power type Diesel–electric Builder EMD BLW Model GT46MAC (1997-2007) GT46ACe (2007-2016) JT46ACe (2013-2018) Build date (EMD) 1997–1998 (BLW) 2002–2018 Total produced WDG-4: 1188 WDG-4D: 583 (Mainline Production has stopped, but happens occasionally for Non-Railway Customers)
Specifications Configuration: ​  • UIC Co′Co′  • Commonwealth Co-Co Gauge 5 ft 6 in (1,676 mm) Trucks HTSC Length 21.26 m (69 ft 9 in) Height 4.11 m (13 ft 6 in) Axle load 21,000 kg (46,000 lb) Loco weight 126,000 kg (278,000 lb) or 126 t (124 long tons; 139 short tons) Fuel type Diesel fuel Fuel capacity 6,100 Litres Prime mover EMD 16-710G3B Engine type two-stroke V16 diesel Aspiration turbocharged Displacement 186.2 liters (11,360 cubic inches) Alternator TA-17-CA6A AC Traction motors 1 inverter per truck, AC traction motors Cylinders 16 Transmission diesel–electric Loco brake Air Train brakes Graduated Release Twin Pipe Air Brake, Dynamic Brakes, Blended
Performance figures Maximum speed 105 km/h (65 mph) Power output 4,000 hp (2,980 kW) / 4,500 hp (3,360 kW) Tractive effort 540 kN (120,000 lbf)
Career Operators Indian Railways, Sri Lanka Railways [as locomotive class M-11, Down-tweaked to 3,250 HP (2.4 MW) using a v12-710 prime mover] Numbers WDG-4: 12001–12999 & 70001–70190 WDG-4D: 12681 & 70301–70882

Further construction has been under license in India by the Banaras 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 using IGBT technology to replace the older gate turn-off thyristor technology and along with increase of 500 hp, ie, 4,500 hp (3.4 MW), using the Newly tweaked EMD 16N-710G3B-EC, like the passenger WDP-4B have been produced. Newer versions with widened Piggy-face cab 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, called WDG-4D, based on the passenger variant WDP-4D locos, 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 into EMD GT50AC (aka WDG-5), using a v20-710G prime mover, based on the SD80MAC, 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 serve Odisha Power Generation Corporation (OPGC), in March 2017. Three WDG-4D locomotives currently serve OPGC.^{[as of?]} As of 2024, two new Single-Cab Piggy-face WDG-4 locomotives have been manufactured and rolled out for Obra Thermal Power Station, based at Sonbhadra, Uttar Pradesh.