Indian locomotive class WAP-7

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[dubious ]

Type and origin
Power type Electric
Builder Chittaranjan Locomotive Works, West Bengal, India
Total produced 298 As of December 2016
Gauge 5 ft 6 in (1,676 mm)
Electric system(s) 25 kV 50 Hz AC Overhead
Current collection pantograph
Operators Indian Railways
Numbers 30201 onwards
Locale Northern Railways , South-Central Railway , Eastern Railway , Central Railway , Southern Railway zone , South East Central Railway

WAP 7 is a 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 110–140 km/h (68–87 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), Western Railway (WR), West Central Railways (WCR), East Coast Railway (ECOR). As of August,2016 there are 288 locomotives in service. All the locomotives are fitted with AAR tightlock couplers and chain link couplers.

Now Diesel Locomotive Works (DLW) ,Varanasi started manufacturing WAP-7 Class Locomotives, the first DLW built locomotive is WAP-7 #30509 Varun.

Similarity with Freight 3-Phase Loco WAG 9[edit]

The WAP-7 locomotive is a WAG 9 freight locomotive with modified gear ratios and is set to replace the fleet of WAP 4, the most widely used passenger locomotive today. These types of engines are mostly used by Indian Railways.


With a maximum speed rating of 140 km/h (87 mph),[1][2] 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 130 km/h or 81 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, New Delhi- Rajendra Nagar(Patna) Patna Rajdhani Express and Nizamuddin-Ernakulam Duronto Express, Thiruvananthapuram-Chennai Super-fast Mail.

WAP-7 locomotive can deliver a maximum power of 6,350 hp (4,740 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 Hz 415 V / 750 V AC (called 'hotel load') is provided at either end of the train rake to supply power.[5][6][7]

Technical Specifications[edit]

A WAP-7 Locomotive at Visakhapatnam Railway Station
Technical Specifications
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]
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]

Locomotive Sheds[edit]

The current locomotive sheds which house this locomotive are:

Named Locos[edit]

  • WAP-7 30201 Navkiran
  • WAP-7 30202 Navbharti
  • WAP-7 30209 Navchetak
  • WAP-7 30215 Navgati
  • WAP-7 30295 Navjyoti
  • WAP-7 30479 Thangam
  • WAP-7 30227 Champalal
  • WAP-7 30509 Varun

Trains hauled by WAP-7[edit]

12862 Visakhapatnam bound Dakshin Link Express with WAP7
12952 Mumbai Rajdhani Express with a WAP-7 engine at New Delhi
Ghaziabad WAP-7 #30284 hauling Bhubaneswar Rajdhani express departs Balasore
Telangana Express with a WAP -7 loco
12717 Ratnachal Express hauled by WAP -7
12713 (BZA-SC) Satavahana Express hauled by WAP -7
GZB WAP7 in Duronto livery with 12952 Mumbai Rajdhani Express
12136 Pune Nagpur Express Hauled by Ajni WAP-7 loco.
(Bellampalli-Hyderabad) Intercity Express hauled by 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 72 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 IST after leaving Howrah at 8.15 am IST. 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]


  1. ^ PTI. "New energy-efficient loco introduced for high speed trains". Economic Times. Retrieved Feb 9, 2012. 
  2. ^, retrieved 2015-10-31  Missing or empty |title= (help)
  3. ^ "New energy-efficient loco introduced for high speed train". Economic Times. 9 Feb 2012. Retrieved 25 Aug 2012. 
  4. ^ "Southern Railway inducts fast locomotive". The Hindu. 18 Oct 2012. 
  5. ^ "Train had WAP-7 engine, 'black box' may reveal cause". Zee News. 9 Aug 2010. Retrieved 25 Aug 2012. 
  6. ^ "Recent Developments". Chittaranjan Loco works. Retrieved 25 Aug 2012. 
  7. ^ "Development of Electric locomotive with Head On Generation (HOG) facility" (PDF). Indian Railways. 
  8. ^ a b c d e f g h i j k l m n "Recent Developments". IRFCA. 
  9. ^ "Engine failure behind Kalka Mail tragedy". IBN Live. 13 July 2011. Retrieved 14 July 2011. 

External links[edit]