Loco naming confusion

Once again, many people have reported that they are confused how locomotives in India are named, so once again I am going to explain you.

The first letter (gauge)

• W – Indian gauge (the "W" Stands for Wide Gauge) – 5 ft 6 in (1,676 mm)

• Y – metre gauge (the "Y" stands for Yard Gauge) – 3 ft 3 3⁄8 in (1,000 mm)

• Z – narrow gauge – 2 ft 6 in (762 mm)

• N – narrow gauge (toy gauge) – 2 ft (610 mm)

The second letter (motive power)

• D – diesel

• C – DC electric (can run under DC overhead line only)

• A – AC electric (can run under AC overhead line only)

• CA – both DC and AC (can run under both AC and DC overhead line); 'CA' is considered a single letter

• B – Battery electric locomotive (rare)

The third letter (job type)

• G – goods

• P – passenger

• M – mixed; both goods and passenger

• S – shunting (also known as switching engines or switchers in the USA and some other countries)

• U – multiple units (EMU/DMU)

• R – Railcars

For example, in "WDM 3A":

• "W" means broad gauge

• "D" means diesel motive power

• "M" means suitable for both goods and passenger service

• "3A" means the locomotive's power is 3,100 hp ('3' stands for 3000 hp, 'A' denotes 100 hp more)

Or, in "WAP 5":

• "W" means broad gauge

• "A" mean AC electric traction motive power

• "P" means suitable for Passenger service

• "5" denotes that this locomotive is chronologically the fifth electric locomotive model used by the railways for passenger service.

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