Indian locomotive class WAP-4

From Wikipedia, the free encyclopedia
Jump to: navigation, search
WAP4 WAG7 02112014.jpg
A WAP4 attached to WAG7 at Kazipet Junction
Type and origin
Power type Electric
Builder Chittaranjan Locomotive Works, West Bengal, India
Build date 1993 till December 2, 2015
Total produced 776 as of August 2016 (Production Ceased)
 • AAR C-C
 • UIC Co'-Co'
Gauge 5 ft 6 in (1,676 mm)
Bogies Co-Co Flexicoil Mark 1 cast bogies; primary and secondary wheel springs with bolsters
Wheel diameter New:1,092 mm (3 ft 7 in)
Half worn: 1,055 mm (3 ft 5 12 in)
Full worn: 1,016 mm (3 ft 4 in)
Length 18.794 m (61 ft 7 2932 in)
Width 3.179 m (10 ft 5 532 in)
Height 4.272 m (14 ft 316 in)
Axle load 18,800 kg (41,400 lb)
Loco weight 112,800 kg (248,700 lb)
Electric system(s) 25 kV 50 Hz AC AC Overhead
Current source pantograph
Traction motors Hitachi HS15250
Loco brake Air/[hand brakes]
Train brakes Air
Safety systems Slip control, Over voltage relay, Main overload relay, Earth Fault Relay, Low Pressure Governor, Brake Cylinder Cutoff Valve, Train parting alarms and No OHE volt relay
Performance figures
Power output Continuous: 5,060 hp (3,773 kW)
Tractive effort 30,800 kgf (302 kN; 68,000 lbf)
Operators Indian Railways
Numbers 22061 and from 22201 to 22999 and 25000 to 25051
Locale All over India
Disposition Active
WAP-4 loco of Erode shed hauling an Express train in India

WAP - 4 is a widely used passenger electric locomotive used in India.

The locomotive was developed after a previous class WAP-1 was found inadequate to haul the longer, heavier express trains (24-26 coaches) that were becoming the mainstay of the Indian Railways network. It was introduced in 1994, with a similar bodyshell to the WAP-1 class, but with Hitachi traction motors.

Electricals are traditional DC loco type tap changers, driving 6 traction motors arranged in Co-Co fashion. This locomotive has proved to be highly successful, with over 750 units in service. Newer examples have been fitted with Microprocessor Controlled diagnostics, Static Converter units (instead of arnos) and roof mounted Dynamic (Rheostatic) Brakes.

The locomotive can be seen in service across the electrified network of Indian Railways and is based out of 14 sheds (depots).

The last locomotive produced by the Chittaranjan Locomotive Works (CLW) was numbered 25051 in December 2015 and production of this locomotive has been stopped.

A WAP-4 class locomotive 22820 of Indian Railway belonging to shed Royapuram, bringing the Trivandrum - Nagercoil Passenger train to Nagercoil Jn.


The loco has a streamlined twin cab carbody design, with top-mounted headlamps. The first 150 or so units had the headlamp mounted at waist level, with the lights being mounted in a protruding nacelle. Some earlier locos, especially from the Erode loco shed have the headlamps placed on the top. Later on the headlamps were placed in a recessed nacelle, and from road #22579 onward, the headlamps were moved to the top. Also they have digital notch repeaters.

Newer locos also feature larger windshields, more spacious driver cabin with bucket type seats and ergonomic controls. The control panel also features a mix of digital and analog displays in newer units (all analog display in older versions).

Original units were weighed 120 tonnes, which was brought down to 112 tonnes through the usage of lighter material.

Some of the WAP-1 and WAP-3 and all the WAP-6 units were rebuilt to WAP-4 specifications after replacing the bogies & electricals.

It has different underframe for handling larger buffing loads. Some units are fitted with speed recorders and some changes to control electronics. Some units also have data recorders for energy consumption. Some are even fitted with windshield washers. Few were provided with signalling lamps.

Technical variants include WAP-4E which are probably fitted with electronic sensor for sensing loss in pressure in pipes.

The Hitachi traction motors are the ones used on freight engines. It was a challenge to put these in a passenger engine due to weight constraints. So the transformer is aluminum foil-wound and aluminum chequered plates are used for reducing the weight.

415 volts, 3 phase, 50Hz power supply is used to drive various auxiliary motors like Traction motor blowers, Transformer radiator blower, Transformer oil pump, Smoothing Reactor Blowers, Silicon Rectifier Blowers, Battery charger. The 3 phase, 415 volt supply is obtained from single phase supply by Arno converter or Static converter.

Indian railways has installed microprocessor based fault diagnostic system and Vigilance Control Device for the enhancement of safety and reliability of electric Locomotives. Some of the newly manufactured WAP-4 locomotives also have air conditioning system for the comfort of loco pilots.


If the average weight of ICF coach is 55 tonnes then it can haul the following capacity in tonnes:

Grade\KPH Start 20 40 60 70 80 90 100 110 120 130 140 150 160
Level 1500+ 1500+ 1500+ 1500+ 1500+ 1500+ 1500+ 1500+ 1500+ 1500+ 1500+ 1155 805 570
1 in 500 1500+ 1500+ 1500+ 1500+ 1500+ 1500+ 1500+ 1500+ 1500+ 1500+ 1105 805 565 400
1 in 200 1500+ 1500+ 1500+ 1500+ 1500+ 1500+ 1500+ 1320 1230 1035 730 535 375 260
1 in 150 1500+ 1500+ 1500+ 1500+ 1500+ 1500+ 1405 1090 1020 860 610 445 310 215
1 in 100 1500+ 1570 1490 1405 1365 1195 1020 795 750 635 445 320 220 145
1 in 50 1160 770 750 720 710 625 530 410 390 325 220 150 90 45

Technical specifications[edit]

A WAP-4 Locomotive at Secunderabad
Technical Specifications of WAP-4[2]
Gear Ratio 23:58 (One loco, #22559, was said to have a 23:59)
Transformer 5400 kVA, 32 taps
Transformer cooling Forced oil with Forced Air
Transformer Insulation A
Pantographs Two Stone India (Calcutta) AM-12.
Rectifiers Two silicon rectifiers
Rectifier Cooling Forced air
Current Ratings 1000 A for 10 min, 900 A continuous
Drive arrangement Gear pinion
Number of sandboxes 4
2 headlights 90 W, 24 V
Lead acid battery 10 Batteries each of 11V, 75 Ah Capacity.
Arno Converter 1420 rpm
2 Elgi Compressors 1000 l/minute at 7.5 kg/cm2.
2 compressor motors 3 phase 12.5 hp and 380 V
2 SF India Ltd. Traction motor blowers MLBR-42.5-144 type
2 Siemens Traction motor blower motors 22 kW, 415 V, 50 A and 2820 rpm
2 SF India Ltd. Smoothing Reactor Blower PFTA-50, ARR6 type
Traction Motor Suspension Axle-hung, nose suspended
Traction motor weight 3650 kg
Armature temperature rise 90 °C
Field temperature rise 70 °C
Commutator temperature rise 85 °C
Armature coil resistance at 110 °C 0.0126 ohms
Field coil resistance at 110 °C 0.0117 ohms
Commutator coil resistance at 110 °C 0.089 ohms
Traction motor continuous rating 950 hp, 750 V, 900 A and 895 rpm
Traction motor 1 hour rating 1030 hp, 750 V and 877 rpm
Traction Motor air gap main place 6.35 mm
Traction motor air gap inter-pole 10 mm
Traction motor 6 P
2 SF India Ltd. silicon rectifier blower 3100–3200 m/hr
2 Rectifier blower motor 22 kW, 415 V, 8 A, 2860 rpm and 60 kg(approx)
Oil cooler blower motor 30 hp, 380 V, 43 A and 1450 rpm
BEST and Co. Pvt. Ltd. Transformer Oil Pump 750 l/minute
Oil pump motor 3.3 kW, 415 V, 6.6 A and 2865 rpm
SL-30 type smoothing reactor 1250 V and 1350 A.
Smoothing reactor resistance at 110 °C 0.00718 ohms
Notches 32

Image Gallery[edit]

Sheds Holding WAP-4[edit]

Sheds holding WAP4s as of June 2017 :

Shed Number of locos Railways Service Status
Erode (ED) 113 Southern Railway (SR) All locomotives in service
Howrah (HWH) 91 Eastern Railway (ER) All locomotives in service
Santragachi (SRC) 80 South Eastern Railway (SER) WAP 4 22330 condemned
Itarsi (ET) 75 West Central Railway (WCR) All locomotives in service
Vadodara (BRC) 72 Western Railway (WR) All locomotives in service
Mughalsarai (MGS) 68 East Central Railway (ECR) WAP 4 22753 retired
Kanpur (CNB) 48 North Central Railway (NCR) All locomotives in service
Bhusawal (BSL) 43 Central Railway (CR) All locomotives in service
Ghaziabad (GZB) 42 Northern Railway (NR) All locomotives in service
Lallaguda (LGD) 40 South Central Railway (SCR) All locomotives in service
Royapuram (RPM) 28 Southern Railway (SR) All locomotives in service
Vijayawada (BZA) 28 South Central Railway (SCR) All locomotives in service
Visakhapatnam (VSKP) 21 East Coastal Railway (ECoR) All locomotives in service
Ludhiana (LDH) 15 Northern Railway (NR) All locomotives in service
Arakkonam (AJJ) 10 Southern Railway (SR) All locomotives in service

Accidents and incidents[edit]

On 13 February 2009 Coromandel Express derailed near Jajpur Road about 100 km (62 mi) away from Bhubaneswar in Orissa killing at least 15 people and leaving several injured, some critically. The train was hauled by Santragachi-based WAP 4 #22330 locomotive which got damaged beyond economical repair and therefore had to be condemned.

See also[edit]



  1. ^ "Trainweb". 
  2. ^ "Indian AC electric loco information". Retrieved 2013-04-03. 


  • Hughes, Hugh (1996). Indian Locomotives: Part 4 – 1941–1990. Harrow, Middlesex: The Continental Railway Circle. ISBN 0-9521655-1-1. 

External links[edit]