The Classification Syntaxes
The first letter (gauge)
- W-Indian broad gauge (The "W" Stands for Wide Gauge - 5 Feet 6 inches)
- Y-metre gauge (The "Y" stands for Yard Gauge - 3 Feet or 1000mm)
- Z-narrow gauge(2 ft 6 in)
- N-narrow gauge (2 ft)
The second letter (motive power)
- D-Diesel
- C-DC electric (can run under DC traction only)
- A-AC electric (can run under AC traction only)
- CA-Both DC and AC (can run under both AC and DC tractions), '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-Used for shunting (Also known as switching engines or switchers in United states and some other countries)
- U-Electric multiple units (used as commuters in city suburbs)
- R-Railcars
For example, in "WDM 3A":
- "W" means broad gauge
- "D" means diesel motive power
- "M" means suitable for mixed(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.
Read more about this topic: Locomotives Of India