Locomotive Types – Complete Railway GK Notes

1. Definition & Basic Classification

Locomotive = self-propelled prime-mover that hauls rolling stock but does not carry paying load itself.
Indian Railways (IR) classifies by:

• Traction – Steam / Diesel / Electric (AC/DC)
• Axle-Load & Power – W (Wide gauge), Y (Metre), Z (Narrow), then horsepower band (5th digit)
• Purpose – Freight, Passenger, Mixed, Shunting, Trip, Banker

2. Steam Locomotives (Phased-out 1995-2000)

• First run in India: 16 Apr 1853, Bori Bunder–Thane, GIPR, loco “Lord Falkland” (0-4-0 tank, 8 t).
• Last commercial steam: 1998 (NWR, Jodhpur division).
• Last steam shed closed: 2000, Siliguri.
• Preserved heritage: 8 World Heritage Hill Railways (Nilgiri, Darjeeling, Kalka-Shimla, etc.) still operate steam for tourism.
• Notable classes:
  • WP (4-6-2) – “P” for passenger, 1950s, 19 t axle, 74 km/h design.
  • YP (2-8-2) – metre-gauge goods, 1952.
  • WG (2-8-2) – BG freight work-horse, 1950-70s.
• Boiler pressure: 14–18 kg/cm²; grate area 2.8–4 m²; thermal efficiency ~6-8 %.

3. Diesel Locomotives

3.1 Evolution

• First diesel loco: 1954, YDM-1 (Metre-gauge) from ALCO USA, 700 hp.
• First BG diesel: 1957, WDM-1, 1950 hp, ALCO.
• First indigenous: 1961, CLW-built WDM-2 (2600 hp).
• Present fleet: 5,869 diesel locos (31-03-2023, MoR data).

3.2 Current Diesel Classes (IR 2024)

3.3 Technical Highlights

• Transmission: Diesel-electric (98 % fleet), Diesel-hydraulic (old shunters only).
• EMD 16-710G3B engine: 4500 hp, 45 ° V16, turbocharged, fuel 185 g/kWh (BS-III).
• HVLS (High-Adhesion) bogies: WDG-4D uses fabricated trimount bogie, starting TE 52 t.
• Fuel capacity: 5000 L (EMD), 6000 L (WDG-5).
• Sheds: 43 diesel sheds; largest – Gooty (GY) with 450+ locos.

3.4 Environment & Updates

• Mission 100 % electrification → Diesel locos being converted to “Head-on-Generation” (HOG) compatible; no new diesel ordering after 2018-19.
• Dual-mode “Gati-Shakti”: 2022, 2 × 4500 hp WDG-4 fitted with 750 V dc electric auxiliary; pilot only.

4. Electric Locomotives

4.1 Traction Systems in India

• 25 kV 50 Hz AC – 92 % of route (64,689 RKM electrified till 31-03-2024).
• 1500 V DC – Mumbai WR & CR suburban only (→ under conversion to 25 kV; target 2026).
• 750 V DC 3rd rail – Kolkata Metro (own network).

4.2 Historic Milestones

• First 1500 V DC: 1925, Harbour line, EMU sets.
• First 25 kV AC: 1960, CLW-built WAM-1 (A = AC, M = Mixed), 2840 hp, SNCF design.
• First 3-phase IGBT: 2000, WAP-5 (6000 hp, 160 km/h).
• First 9000 hp: 2017, WAG-9 “Prime” by CLW.

4.3 Current AC Electric Classes (2024)

4.4 Technical Specifications

• Power electronics:
  • WAP-5/7/WAG-9 use Hitachi IGBT-based 3-phase drive.
  • Line converter (4-Q), DC-link 2800 V, Inverter 3 × 1050 V rms.
• Regenerative braking: 260 kN (WAP-7), saves 30 % energy on ghats.
• Transformer: 7500 kVA (WAG-9H), 32 taps, 45 % margin.
• Axle-load variants: 22.5 t (pass), 25 t (freight).
• Crash-worthy cab: WAP-7 & WAG-9 2020-onwards.

4.5 Production & Deployment

• CLW (Chittaranjan): 479 locos in 2022-23 (highest ever).
• BHEL Jhansi: 100+ WAG-12B (12000 hp, twin-cab).
• Total electric: 7,439 locos (31-03-2023).
• Largest electric shed: Bondamunda (BNDM) – 400+ WAG-9.

5. Special-Purpose & Emerging Types

• Banker locos: WAG-7 3-phase modified, 1:37 gradient, Ghats (Bhor, Thull, Darjeeling).
• Trip shed & Shunters: 1400 hp WDS-6, 700 hp WDS-4 (diesel).
• Battery locos: 120 t, 540 V lead-acid, used in yards (no exhaust).
• Hybrid “Hydrogen”: 2023, H2-EMU prototype 600 kW by DLW & RDSO.
• Aluminium-body 160 km/h: 2024 trial, 3-phase, 7850 kg lighter → 14 % energy save.

6. Comparison Snapshot (2024)

7. Weightage in Railway Exams

• RRB NTPC CBT-2: 2-3 questions every shift.
• RRB JE/ALP CBT-2: 4-5 technical MCQs (power circuit, traction motor, rpm).
• RPF SI: 1-2 GK-based.
  Trend: Mission Electrification, WAG-12B, regen braking, highest hp locos are hot.

Quick-Fire Facts to Memorise

1. First loco in India – Lord Falkland (Steam, 1853).
2. Last steam shed – Siliguri (closed 2000).
3. First 25 kV loco – WAM-1 (1960).
4. First 3-phase loco – WAP-5 (2000).
5. Highest hp single-cab – WAG-9H 9000 hp.
6. Highest hp twin-cab – WAG-12B 12000 hp (6000+6000).
7. Lightest high-speed – WAP-5 78 t.
8. Heaviest diesel – WDG-5 138 t.
9. Starting TE record – WAG-9 55 t.
10. Energy-saving tech – Regenerative braking (260 kN).
11. Fuel consumption diesel – 185 g/kWh (EMD).
12. DC-DC conversion target – Mumbai 1500 V DC → 25 kV by 2026.
13. Hydrogen pilot – 600 kW DLW 2023.
14. 100 % electrification target – Dec 2024 (achieved 64,689 RKM 2024).
15. CLW production high – 479 locos FY 23.

Multiple-Choice Questions (15+)

Revise the facts, practise the MCQs, and you are set to score full marks on “Locomotive Types” in every Railway exam. All the best!