Indian locomotive class WAP-7

From Wikipedia, the free encyclopedia
Jump to: navigation, search
GZB WAP7 in Duronto livery with 12952 Mumbai Rajdhani Express.JPG
A Ghaziabad WAP7 in Duronto livery hauling the Mumbai Rajdhani Express
Power type Electric
Builder Chittaranjan Locomotive Works, West Bengal, India
Gauge 5 ft 6 in (1,676 mm)
Current collection
25 kV, 50 Hz overhead AC with pantograph
Top speed Test Run:180 km/h (112 mph), Operational: 140 km/h (87 mph)
Power output 6,350 hp (4,735 kW)
Railroad(s) Indian Railways
Number 30xxx series
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 km per hour 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 November 2013, there are 180 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 160  km/h (IR restricts it to 140 km/hr), 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 (1430–1550t) at 140 km/h per hour.[1] It is also known to haul 18 heavyweight Air Conditioned coaches (1120t) in 1:40 inclines single-handedly. At a trial conducted by Indian Railways, it clocked a speed of 184 km/h. It is the most successful passenger locomotive in the Indian Railways portfolio 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.[2] 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 6000 HP 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.[3] 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.[4][5][6]

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[7]
Traction Motors 6FRA 6068 3-phase squirrel-cage induction motors (850 kW, 2180V, 1283/2484 rpm, *270/310A; Weight- 2100 kg, forced-air ventilation, axle-hung, nose-suspended; Torque 6330/7140Nm. *95% efficiency.)[7]
Gear Ratio 72:20[7]
Axle load 20.5t[7]
Power 6350 HP[7]
Wheel diameter 1092mm new, 1016mm wor[7] n
Wheelbase 15700mm[7]
Bogies Co-Co, Fabricated Flexicoil Mark IV bogies; bogie wheelbase 18500mm + 18500mm[7]
Unsprung mass per axle 3.984t[7]
Length over buffers 20562mm[7]
Length over headstocks 19280mm[7]
Body width 3152mmn[7]
loco weight 123t[7]
Cab length 2434mm[7]
Pantograph locked down height 4255mm[7]


The current locomotive sheds which house this locomotive are:

Trains hauled by WAP-7[edit]

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

Accidents and incidents[edit]

Main article: Kalka Mail derailment

Kalka Mail which derailed on 10 July 2011 was being hauled by a WAP-7 locomotive.[8]

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 (30221) has been re-railed and is undergoing fault diagnostics and repairs.

See also[edit]


External links[edit]