Rail Transport in India - Locomotives

Locomotives

Indian Railways use a specialised classification code for identifying its locomotives. The code is usually three or four letters, followed by a digit identifying the model (either assigned chronologically or encoding the power rating of the locomotive). This could be followed by other codes for minor variations in the base model.

The three (or four) letters are, from left to right, the gauge of tracks on which the locomotive operates, the type of power source or fuel for the locomotive, and the kind of operation the locomotive can be used for. The gauge is coded as 'W' for broad gauge, 'Y' for metre gauge, 'Z' for the 762 mm narrow gauge and 'N' for the 610 mm narrow gauge. The power source code is 'D' for diesel, 'A' for AC traction, 'C' for DC traction and 'CA' for dual traction (AC/DC). The operation letter is 'G' for freight-only operation, 'P' for passenger trains-only operation, 'M' for mixed operation (both passenger and freight) and 'S' for shunting operation. A number alongside it indicates the power rating of the engine. For example '4' would indicate a power rating of above 4,000 hp (2,980 kW) but below 5,000 hp (3,730 kW). A letter following the number is used to give an exact rating. For instance 'A' would be an additional 100 horsepower (75 kW); 'B' 200 hp (150 kW) and so on. For example, a WDM-3D is a broad-gauge, diesel-powered, mixed mode (suitable for both freight and passenger duties) and has a power rating of 3400 hp (2.5 MW).

The most common diesel engine used is the WDM-2, which entered production in 1962. This 2,600 hp (1.9 MW) locomotive was designed by Alco and manufactured by the Diesel Locomotive Works, Varanasi, and is used as a standard workhorse. It is being replaced by more modern engines, ranging in power up to 5,500 hp (4.1 MW).

There is a wide variety of electric locomotives used, ranging between 2,800 to 6,350 hp (2.1 to 4.7 MW). They also accommodate the different track voltages in use. Most electrified sections in the country use 25,000 volt AC, but railway lines around Mumbai use the older 1,500 V DC system. Thus, Mumbai and surrounding areas are the only places where one can find AC/DC dual locomotives of the WCAM and WCAG series. All other electric locomotives are pure AC ones from the WAP, WAG and WAM series. Some specialised EMU (electric multiple units) are running on Mumbai Suburban System of Central Railway and Western Railway also use dual-power systems, these are new-age rakes manufactured in ICF (Integral Coach Factory) in Perambur usually white and purple livery color. There are also some very rare battery-powered locomotives, primarily used for shunting and yard work.

The only steam engines still in service in India operate on two heritage lines (Darjeeling and Ooty), and on the tourist train Palace on Wheels. Plans are afoot to re-convert the Neral-Matheran to steam. The oldest steam engine in the world in regular service, the Fairy Queen, operates between Delhi and Alwar.