Indian locomotive class WAP-7

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22691 WAP7 130418.jpg
WAP-7 of Tughlakabad Shed
Type and origin
Power typeElectric
BuilderChittaranjan Locomotive Works
Diesel Locomotive Works[1]
Diesel-Loco Modernisation Works
Build date14 November 1998[2] - present
Total produced579 as of January 2019
Gauge5 ft 6 in (1,676 mm)
BogiesCo-Co, Fabricated Flexicoil Mark IV bogies; bogie wheelbase 1,850 mm (72 78 in) + 1,850 mm (72 78 in)
Wheel diameter1,092 mm (43 in) new, 1,016 mm (40 in) worn
Wheelbase15,700 mm (51 ft 6 18 in)
 • Over beams20,562 mm (67 ft 5 12 in)
Width3,152 mm (10 ft 4 18 in)
 • Pantograph4,255 mm (13 ft 11 12 in)
Axle load20.5 t (20.2 long tons; 22.6 short tons)
Loco weight123 t (121 long tons; 136 short tons)
Power supply3-phase 50 Hz 415 V / 750 V
Electric system/s25 kV 50 Hz catenary
Current pickup(s)Pantograph
Traction motors6FRA 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)
~88% efficiency.
Gear ratio72:20
Loco brakeAir and regenerative
Train brakesAir
Performance figures
Maximum speed140 km/h (87 mph)
Power outputContinuous : 6,122 hp (4,565 kW)
Tractive effortStarting : 322 kN (72,000 lbf)

Continuous : 228 kN (51,000 lbf) at 71 km/h
OperatorsIndian Railways
Numbers30201 onwards
First run19 May 2000[3]

The WAP 7 (Wide/broad Gauge AC Electric Passenger, Class 7) is a three-phase AC electric passenger locomotive developed by the Chittaranjan Locomotive Works. It is the most powerful passenger locomotive in the Indian Railways' fleet. It is a passenger variant of the WAG 9 freight locomotive with a modified gear ratio to pull lighter loads at higher speeds. It is capable of hauling 24 coach trains at speeds ranging between 110–140 km/h (68–87 mph), depending on the MPS (Maximum Permissible Speed) of the sector, and is now largely used by Northern Railways (NR), South Central Railways (SCR), Southern Railways (SR), South Eastern Railways (SER), West Central Railways (WCR), and Eastern Railways (ER) among other zones. As of January 2019, there are 579 locomotives in service, all of which are fitted with tightlock couplers (for central buffer coupling) and chain link couplers.In 2018 Diesel-Loco Modernisation Works Started Producing WAP 7 and In February 2017, Diesel Locomotive Works built their first WAP 7 class locomotive.[1]


With a maximum speed rating of 140 km/h (87 mph) 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 was initially used to haul premium train services like the Rajdhani Express, Shatabdi Express and the Duronto Express.[4] As more locomotives were rolled out, the WAP 7 became the official link of several state trains like the Poorva Express, Telangana Express, Kerala Express,Paschim Express and Tamil Nadu Express among others. The locomotives have been used as a regular link for many of the Garib Rath Express services and eventually extended to a significant number of AC Express and Mail/Superfast Express services like Thiruvananthapuram Mail, Mangalore Mail, Bangalore Mail and so on. It is soon becoming the most commonly used passenger locomotive. Upgradations in progress for a higher horsepower and speeds.

30333 WAP-7 locomotive of RPM (Royapuram) shed at Mysore.

The WAP-7 locomotive can deliver 6,120 hp (4,560 kW) continuously, 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 troubleshooting easier.[5]

Head-on Generation (HOG)[edit]

A main feature of some locomotives of this class is that they eliminate the need to have separate End on Generation (EOG) sets or DG (Diesel Generator) sets for supplying power to the train resulting in significant 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 EOG where a power car equipped with diesel generator capable of generating adequate power of 3-phase 50 Hz 415 V / 750 V AC (called 'head-end power') is provided at either end of the train rake to supply power.[6][7][8]

Technical Specifications[edit]

Technical Specifications[9]
Manufacturers Chittaranjan Locomotive Works
Diesel Locomotive Works
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)
~88% efficiency.
Gear Ratio 72:20
Axle load 20.5 t (20.2 long tons; 22.6 short tons)
Wheel diameter 1,092 mm (43 in) new, 1,016 mm (40 in) worn
Wheelbase 15,700 mm (51 ft 6 18 in)
Bogies Co-Co, Fabricated Flexicoil Mark IV bogies; bogie wheelbase 1,850 mm (72 78 in) + 1,850 mm (72 78 in)
Unsprung mass per axle 3.984 t (3.921 long tons; 4.392 short tons)
Length over buffers 20,562 mm (67 ft 5 12 in)
Length over headstocks 19,280 mm (63 ft 3 in)
Body width 3,152 mm (10 ft 4 18 in)
loco weight 123 t (121 long tons; 136 short tons)
Cab length 2,434 mm (95 78 in)
Pantograph locked down height 4,255 mm (13 ft 11 12 in)

Locomotive Sheds[edit]

GZB WAP7 in Duronto livery
Zone Shed Code Name Quantity Introduction Out of Service Notes
NR GZB Ghaziabad 104 19 May 2000 First WAP-7 was operated by NR
SCR LGD Lallaguda 98 26 December 2008
CR AJNI Ajni 47 27 December 2010 First loco transferred from GZB
SR RPM Royapuram 93 21 January 2011 First WAP7 locomotive shed of Southern Railway
ER HWH Howrah 59 20 February 2012 First loco transferred from GMO
SECR BIA Bhilai 25 06 September 2012 First loco transferred from GMO
WCR TKD Tughlakabad 64 25 January 2013 First loco transferred from GZB
WCR ET Itarsi 17 01 December 2018 Recently started Holding WAP7 locos, apart from holding 80+ WAP4 class locos. Locos of this shed serve all routes across WCR.
WR BRC Vadodara 31 01 April 2016
ECoR VSKP Visakhapatnam 14 02 November 2016
SR ED Erode 4 19 October 2017 First loco transferred from RPM
SER TATA Tatanagar 12 18 April 2017
SER SRC Santragachi 22 09 November 2017 First loco transferred from GMO
ECR GMO Gomoh 8 28 November 2018 First loco transferred from VSKP

Named Locos[edit]

A Ghaziabad-based Head On Generation (HOG) WAP-7 hauling Bhubaneswar Rajdhani Express at Balasore, Odisha
  • WAP-7 30201 Navkiran
  • WAP-7 30202 Navbharti
  • WAP-7 30209 Navchetak
  • WAP-7 30215 Navgati
  • WAP-7 30227 Champalal
  • WAP-7 30295 Navjyoti
  • WAP-7 30479 Thangam
  • WAP-7 30509 Varun
  • WAP-7 30521 Varun
  • WAP-7 30543 Ojas
  • WAP-7 30573 Cauvery
  • WAP-7 37073 Shatak


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 a Ghaziabad-based WAP 7 30221. Malfunction of the undergear of the locomotive may have been a reason. The driver of the Kalka Mail said he saw the engine shaking.[10] 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.[11]

On 14 December 2014, the Howrah - New Delhi Poorva Express derailed shortly after leaving Howrah, Kolkata. 11 sleeper coaches and a pantry car (A/C hot buffer car) of the rake jumped the rails in the incident. Due to the derailment occurring when the train was just pulling into its first commercial halt at Liluah, and the usage of LHB coaches, the accident was contained and no casualties were reported. Like the 2011 Kalka Mail derailment, this accident also involved a Howrah-based WAP 7 locomotive.[12]

See also[edit]


  1. ^ a b "Brief History of DLW". Ministry of Railways, Government of India. Retrieved 30 December 2017.
  2. ^ "New generation locomotives from Chittaranjan". The Hindu. 2 February 2000. Retrieved 30 December 2017.
  3. ^ "Indian Railways Locomotive: 30201". IRFCA. Retrieved 30 December 2017.
  4. ^ "New energy-efficient loco introduced for high speed train". Economic Times. 9 Feb 2012. Retrieved 25 Aug 2012.
  5. ^ "Southern Railway inducts fast locomotive". The Hindu. 18 Oct 2012.
  6. ^ "Train had WAP-7 engine, 'black box' may reveal cause". Zee News. 9 Aug 2010. Retrieved 25 Aug 2012.
  7. ^ "Recent Developments". Chittaranjan Loco works. Retrieved 25 Aug 2012.
  8. ^ "Development of Electric locomotive with Head On Generation (HOG) facility" (PDF). Indian Railways.
  9. ^ "Recent Developments". IRFCA.
  10. ^ "Engine failure behind Kalka Mail tragedy". IBN Live. 13 July 2011. Retrieved 14 July 2011.
  11. ^ "Death by Design". Living Media India Limited. Retrieved 31 December 2017.
  12. ^ "12 coaches of Poorva Express derail, no casualty". The Indian Express [P] Ltd. Retrieved 31 December 2017.

External links[edit]