Locomotive types

Many of the passengers who travel in trains are either not aware of what is a locomotive type or are confused by their types written in short form on it (like WDS 6) ?

The locomotives in Indian Railways can be broadly classified into 3 categories based on their gauge :

  1. Narrow Gauge Z or N.
  2.  Meter Gauge Y.
  3.  Broad Gauge W.

These can be further classified on the basis of their powers i.e. from where do they get or generate power :


Diesel D

Electic A or C or CA

Battery locomotives B.

These are then classified into 3 more sub categories based on their purpose or use :

  1. Locomotives used in only freight trains are referred as Goods G.
  2. Locomotives used in only passenger trains (all trains that carry passengers) are referred as Passenger P.
  3. Locomotives used in both the above tasks are referred as of Mixed type M.
  4. Locomotives used for shunting B.

The Type syntax :

The first letter (gauge)

  • W – Indian Broad 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 38 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 type)

  • D – diesel
  • C – DC (Direct Current) electric (can run under DC overhead line only)
  • A – AC (Alternating Current) 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 or its use)

  • 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.

The number after this is the locomotive generation number.

Now lets try on the type syntax “WDS 6”

– Broad Gauge.
– Diesel
– Shunting.
– Locomotive generation.