Indian locomotive class WAP-7

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GZB WAP7 in Duronto livery with 12952 Mumbai Rajdhani Express.JPG
A Ghaziabad WAP 7 in Duronto livery hauling the Mumbai Rajdhani Express
Type and origin
Power type Electric
Builder Chittaranjan Locomotive Works, West Bengal, India
Gauge 5 ft 6 in (1,676 mm)
Electric system(s) 25 kV 50 Hz AC AC Overhead
Current collection
Performance figures
Maximum speed Test Run:180 km/h (112 mph)
Operational: 140 km/h (87 mph)
Power output 6,350 hp (4,735 kW)
Operator(s) Indian Railways
Number(s) 30201 onwards
Locale Northern Railways, South-Central RailwayEastern Railway South East Central Railway

WAP 7 is a moderate speed high power locomotive developed by Chittaranjan Locomotive Works by modifying the gear ratio of existing WAG 9 class. It is capable of hauling trains at speeds ranging between 140 and 180 kilometres per hour (87 and 112 mph) and is now largely used by Northern Railways (NR), South Central Railways (SCR), Southern Railways (SR), Eastern Railways (ER), South East Central Railway (SECR), Central Railways (CR), West Central Railways (WCR). As of October 2014, there are 205 locomotives in service.

Similarity with WAG 9[edit]

The WAP-7 is actually a modified version of the WAG 9 freight locomotive with modified gear ratios and is set to replace the fleet of WAP 4's, the most widely used passenger locomotive today. The process will be a very slow one however, with WAP 4s still being produced and the production of WAP-7's increasing at a slow pace.


With a maximum speed rating of 180 km/h (110 mph) (IR restricts it to 140 km/h or 87 mph),[1] the WAP-7 has the highest acceleration figures while hauling mail/express trains. The WAP-7 can also haul loads of 24-26 passenger coaches (1,430–1,550 t or 1,410–1,530 long tons or 1,580–1,710 short tons at 140 km/h or 87 mph).[2] It is also known to haul 18 heavyweight Air Conditioned coaches (1,120 t or 1,100 long tons or 1,230 short tons) on 1:40 (2.5%) inclines single-handedly. At a trial conducted by Indian Railways, it clocked a speed of 184 km/h (114 mph). It is the most successful passenger locomotive on the Indian Railways roster after the WAP-4. It is used to haul premium trains like the Rajdhani Express and the Shatabdi Express apart from other regular mail/express trains.[3] It also regularly hauls other trains like the Hyderabad - New Delhi, H.Nizamuddin-Thiruvananthapuram, H.Nizamuddin-Chennai, H.Nizamuddin-Bangalore, New Delhi-Sealdah and the New Delhi - Mumbai Rajdhani Express and Nizamuddin-Ernakulam Duronto Express.

12952 Mumbai Rajdhani Express with a WAP 7 engine at New Delhi

WAP-7 locomotive can deliver 6,000 hp (4,500 kW) with regenerative braking being one of its salient features. The regenerative braking is deployed on down gradients conserving energy to the tune of 30-35 percent. It has an inbuilt microprocessor based fault diagnostic system to make trouble shooting easier.[4] Another feature of this locomotive is that it eliminates the need to have separate EOG sets for air-conditioning in long distance trains hence providing significant amount of savings on maintenance and running costs. This technology, called HOG or "Head On Generation", transfers electric power from the loco's pantograph to the coaches instead of "End on Generation" in which a Power Car equipped with diesel generator capable of generating adequate power of 3-phase 50-cycle 415V/750V AC (called as hotel load) is provided at either end of the train rake to supply power.[5][6][7]

A 24-coach (1500t) passenger rake can be accelerated to 110 km/h in 180 seconds (over 3.7 km) by a WAP-7; to 120 km/h in 235 sec. (5.3 km); 130 km/h in 302 sec. (7.9 km); 140 km/h in 390 sec. (9.1 km); 150 km/h in 490 sec. (11.1 km); and to 160 km/h in 610 sec. (13.1 km).

Technical specifications[edit]

Manufacturers Chittaranjan Locomotive Works[8]
Traction Motors 6FRA 6068 3-phase squirrel-cage induction motors (850 kW (1,140 hp), 2180 V, 1283/2484 rpm, *270/310A; Weight- 2,100 kg (4,600 lb), forced-air ventilation, axle-hung, nose-suspended; Torque 6,330–7,140 N·m (4,670–5,270 lbf·ft). *95% efficiency.)[8]
Gear Ratio 72:20[8]
Axle load 20.5 t (20.2 long tons; 22.6 short tons)[8]
Power 6,350 hp (4,740 kW)[8]
Wheel diameter 1,092 mm (43 in) new, 1,016 mm (40 in) worn[8]
Wheelbase 15,700 mm (51 ft 6 18 in)[8]
Bogies Co-Co, Fabricated Flexicoil Mark IV bogies; bogie wheelbase 1,850 mm (72 78 in) + 1,850 mm (72 78 in)[8]
Unsprung mass per axle 3.984 t (3.921 long tons; 4.392 short tons)[8]
Length over buffers 20,562 mm (67 ft 5 12 in)[8]
Length over headstocks 19,280 mm (63 ft 3 in)[8]
Body width 3,152 mm (10 ft 4 18 in)[8]
loco weight 123 t (121 long tons; 136 short tons)[8]
Cab length 2,434 mm (95 78 in)[8]
Pantograph locked down height 4,255 mm (13 ft 11 12 in)[8]


The current locomotive sheds which house this locomotive are:

  1. Ghaziabad (Code:GZB)
  2. Lallaguda (Code:LGD)
  3. Ajni (Code:AJNI)
  4. Howrah (Code:HWH)
  5. Bhilai (Code:BIA)
  6. Royapuram (Code:RPM)
  7. Tughlakabad (Code:Tkd)

Trains hauled by WAP-7[edit]

Chhattisgarh Express being hauled by a WAP-7 class electric loco

Pooja Express New delhi to Jammu Tawi with WAP 7

Accidents and incidents[edit]

On 10 July 2011 Kalka Mail derailed on the Kanpur-Fatehpur line near the Fatehpur railway station , more than 69 persons died and 200 were injured,some critically. The train was hauled by Ghaziabad-based WAP 7 30221. Malfunction of the undergear of the locomotive could also be a reason. The driver of the Kalka Mail said he saw the engine shaking.[9] A post-accident diagnostic revealed that the first axle (leading) of the locomotive registered a jerk and the fourth axle (trailing bogie) showed loss of contact of the wheel with the track. The locomotive in question has been re-railed and is undergoing fault diagnostics and repairs.

On 14 December 2014 the 12381 UP Howrah - New Delhi Poorva Express derailed at 8.27 am after leaving Howrah at 8.15 am. 11 sleeper coaches and a pantry car (AC Hot Buffer Car) of the New Delhi-bound Poorva Express derailed at Liluah shortly after leaving Howrah station. There was no casualty or injury to any passenger. Like Kalka Mail this train was also hauled by Ghaziabad-based WAP 7. But the locomotive did not face much damage hence after undergoing fault diagnostics and repairs the locomotive has been re-railed.

See also[edit]


External links[edit]