Classification of Indian Locomotives

July 10, 2019 - Reading time: 11 minutes

You should have seen the letters WDP-3A ,WDM-3F or some thing like this painted on the front and sides of an engine,but have you guys ever wondered what these letters stand for?

Classification of Indian Locomotives
You should have seen the letters WDP-3A ,WDM-3F or something like this painted on the front and sides of an engine,but have you guys ever wondered what these letters stand for?
Well, these letters are used to classify these locos according to their track gauge,the motive power,the work they are suited for and their power or model number.

The first letter (gauge)

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 – electric multiple unit (used to carry commuters in city suburbs)
  • R – Railcar

The fourth letter is used to denote locomotives’ chronological model number. However, from 2002 a new classification scheme has been adopted. Under this system, for newer diesel locomotives, the fourth letter will denote their horsepower range. Electric locomotives don’t come under this scheme and even all diesel locos are not covered. For them this letter denotes their model number as usual.

For them this letter denotes their model number as usual.

  • 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

A locomotive may sometimes have a fifth letter in its name which generally denotes a technical variant or subclass or subtype. This fifth letter indicates some smaller variation in the basic model or series, perhaps different motors, or a different manufacturer. With the new scheme for classifying diesel locomotives (as mentioned above) the fifth item is a letter that further refines the horsepower indication in 100 hp increments: ‘A’ for 100 hp, ‘B’ for 200 hp, ‘C’ for 300 hp, etc. So in this scheme, a WDP-3A refers to a 3100 hp loco, while a WDM-3F would be a 3600 hp loco.