The EMD GT46MAC is a freight-hauling diesel-electric locomotive with AC electric transmission built by General Motors Electro-Motive Division
in 1997–1998 for Indian Railways

Indian Railways

Indian Railways , abbreviated as IR , is a departmental undertaking of Government of India, which owns and operates most of India's rail transport. It is overseen by the Ministry of Railways of the Government of India....

, where they are classed as WDG-4.
Thirteen were built by EMD as order #958647, and a further eight were exported in kit form and were assembled in India. The class entered service in 1999.
Further construction has been under license in India by the Diesel Locomotive Works

Diesel Locomotive Works

The Diesel Locomotive Works in Varanasi, India, is a production unit owned by Indian Railways, for which it manufactures diesel-electric locomotives and spare parts.-Company:...

 (DLW); more than 60 additional locomotives have been built . They are numbered from #12000 upward. A similar type, the EMD GT46PAC

EMD GT46PAC

The EMD GT46PAC is a passenger-hauling diesel-electric locomotive with AC electric transmission designed by General Motors Electro-Motive Division and built by both GM-EMD and under license by Diesel Locomotive Works of Varanasi, India for Indian Railways as their classes WDP-4, WDP-4B and WDP-4D...

, has also been produced for passenger service in India.

, EMD and DLW have begun building GT46MACs using IGBT technology to replace the older Gate turn-off thyristor

Gate turn-off thyristor

A gate turn-off thyristor is a special type of thyristor, a high-power semiconductor device. GTOs, as opposed to normal thyristors, are fully controllable switches which can be turned on and off by their third lead, the GATE lead.-Device description:...

technology.
Newer editions with 4500hp have been produced. More than 250 locos are operational now.

History

The WDG4's first operation started in 1999 with the numbering starting from 12001; this loco can still be seen in a splendid condition and is homed at the parent shed of Hubli. Hubli Diesel Locomotive Shed has been operational since 1999, and it houses the maximum number of WDG4s from 12001-12064, 12067-12153, 12156, 12169, 12189, 12227, 12276, 12311–12313, 12325, 12326.
The original WDG4s from 12001–12021 were imported and later on DLW has started manufacturing it indigenously. With six traction motors this locomotive has the capability of touching 105 km/hr with a fully loaded freight train of 58 wagons. The loco has been praised for its ability to work smoothly in regions with massive gradients and especially in the Braganza Ghats and the Subrahmanya ghats having a gradient of 1:45 and 1:50.

New Specifications

A new model of the WDG4 has been manufactured which develops 4500hp and has a fibreglass cabin, among other features. These locomotives have been specified as GT46ACe models. WDG4s are being looked into as future locomotives for freight operations in non-electrified sections of India. A new EMD locomotive classed WDG5 with 5500hp is under development at DLW.

Sheds Holding WDG4s

• Hubli (UBL)
• Silliguri (SGUJ)
• Lucknow (LKO)
• Bhagat Ki Kothi (BGKT)
• Sabarmati (SBI)
• Gooty (GY)
• Krishnarajapuram (KJM)
• Raipur (R)
• Pune (PUNE)
• Ponmalai/Golden Rock (GOC)