A locomotive or engine is a rail transport vehicle that provides the motive power for a train. Locomotives were classified by track gauge, motive power, function and power (or model number) in a four- or five-letter code. First letter denotes the track gauge Second letter denotes motive power (diesel or electric) Third letter denotes use (goods, passenger, mixed or shunting) The fourth letter denotes model number. First letter (gauge): W – Broad gauge Y – Metre gauge Z – 2 ft 6 in narrow gauge N – 2 ft narrow (toy) gauge Second letter (motive power): D – Diesel C – DC electric (DC overhead line) A – AC electric (AC overhead line) CA – DC and AC (AC or DC overhead line) B – Battery (rare) Third letter (job type): G – Goods P – Passenger M – Mixed S – Shunting U – Multiple unit R – Railcar WAG-9 Locomotive class WAG-9 is a class of 25 kV AC electric locomotives that was developed by ABB Group for Indian Railways. The model ...