Indian locomotive class WAM-4

The Indian locomotive class WAM-4 is a class of 25 kV AC electric locomotives that was developed in 1970 by Chittaranjan Locomotive Works for Indian Railways. The model name stands for broad gauge (W), alternating current, mixed traffic locomotive, 4th generation. They entered service in March 1971. A total of 500 WAM-4 were built at CLW between 1970 and 1983, which made them the most numerous class of mainline electric locomotive till its successor the WAG-5.
The WAM-4 is one of the most successful locomotives of Indian Railways having served both passenger and freight trains for over 52 years. This class provided the basic design for a number of other locomotives like WCAM-1, WAG-5A, WCG-2, and some WAP-1 models. However, with the advent of new 3-phase locomotives like WAP-5 and WAP-7, the WAM-4 locomotives were relegated to hauling smaller passenger trains and most of the units have been scrapped. A few units are in service performing backup and non-essential duties.

History

Origins

In the 1970s, the Indian Railways started a series of study projects for a high horsepower locomotive. Although the WAG-1/WAG-4 was being introduced, officials believed that a much larger and more capable locomotive was needed, especially to haul Freight trains that was heavy for any existing locomotives. These studies led to initial requirements for a locomotive with a tractive effort of and a speed of.The WAM-4 was conceived while goods traffic was increasing in the 1970s. The era of Co-Co locomotives, led by the enormous popularity of the WDM-2, had revolutionized long-distance travel. With the aim of addressing the shortcomings of the previous WAM-1/2 and WAG-1, WAG-2, WAG-3, WAG-4 classes and remove steam locomotives from IR by a target date of 1990. The WAM-1s were not great successes as some of their advanced features were unsuitable for Indian conditions.
so the designers at RDSO and CLW decided to use the following

Instead of the Bo-Bo bogies of WAM-1/2, ALCO asymmetric Trimount bogies of the WDM-2 were provided for better traction and power.
Silicon rectifiers with speed control by three series-parallel motor combinations and weak field operation.
Auxiliaries from Westinghouse and Kirloskar, S F India and Northey
Air brakes for loco and vacuum train brakes fitted as original equipment with Rheostatic braking also provided
MU operation made possible up to 4 units possible.

Production

Production of these locomotives started in 1970 with #20400 and exactly 500 WAM-4s were built in 13 years with #21399 “Anant” being the last one. Production ended on August 3 1983. WAM-4 though an indigenously produced loco was heavily inspired by French box design and naturally favoured a French TM which was the Alstom made TAO TM. A single WAM-4 can generally haul up to a 24-coach passenger rake. This class proved so successful by virtue of its ruggedness suitable for Indian conditions and simplicity of maintenance. In January 2020, the last WAM-4 units were withdrawn from mainline service. Currently 8 locomotives are doing shunting and departmental works.

Rebuilding

A number of locomotives were rebuilt as WAM-4B in the late 1970s to evaluate Alstom TAO 659 Traction Motors and for exclusive use on freight duties. These 'locos' were ballasted to improve traction and had excellent load-hauling capabilities, This experiment gave rise to the future WAG-5 locos.

Duties

The class was designed for both passenger and freight work. Many of the original locomotives were fitted with vacuum brakes only. With the withdrawal of many WAG-1 and WAM-1 locomotives in the 1990s, the WAM-4 units were given air brakes to prolong their life into the 1990s and beyond.

Sub-classes

This loco class has been seen in many variations, as a lot of workshops and sheds have carried out their own enhancements or modifications to the basic loco design. Although the code indicates a mixed-use loco, most WAM-4's ended up hauling passenger trains.
Variants includeWAM4B or G: Freight only WAM4D or DB: Dual Braked WAM4E: Air Brake only WAM4H: Hitachi Traction Motors instead of AlstomWAM4P: Passenger only WAM4/2S3P: 2 Traction Motors in Series, 3 in ParallelWAM4/6P: 6 traction motors permanently in parallelWAM4/6PE: Air braked, 6 Traction Motors perm. in parallelWAM4/6PDBHS: 6 Traction Motors permanently in parallel, Dual Brakes, High SpeedWAM-4P D: Passenger only

WAM-4P DB 6P and WAM-4 6P D: These are for superfast trains
WAM-4P DB 3P and WAM-4 2S-3P: some superfasts, passengers

The 'DB' or 'D' generally, but perhaps not always, indicates dual-brake capability. 'HS' may be for 'high speed'.'2S', '3P', '6P', etc. indicate traction motors connected in series or parallel. The WAM-4 has six traction motors, and originally they were wired to be available in different configurations at different power settings. At notches up to 14, all motors were in series ; up to notch 21 in series-parallel combinations ; and further notches with all motors in parallel. This is the original configuration of the WCAM-1 series of locomotives too.
The WAM-4 locomotives were later reconfigured to have all motors always in parallel or with the three series-connected pairs in parallel. Some WAM-4 locomotives from CLW are thought to have had the 2S 3P configuration right from the start. The 2S 3P configuration was better for the mixed traffic loads especially as it allowed the locomotives to start hauling larger loads without stalling. With increasing use of the WAM-4 locomotives for passenger traffic the all-parallel configuration was deemed more desirable since it allowed higher speeds and higher acceleration.

Livery

This loco has a wide variety of liveries, with each loco shed having its own livery.
Most of the WAM-4 locomotives now have their MU capability disabled as RDSO disapproves of these locomotives running MU'd over 100 km/h.

Named locomotives

A few WAM-4 locomotives have been named by Indian Railways

Class	Loco Number	Name	Loco Shed	Current status	ref
WAM-4	20401	Rajatabha	Bhillai	Condemned
WAM-4	20420	Sukh Sagar Naveen	Vijayawada	Scrapped
WAM-4	20615	Surubhi	Asansol	Condemned in November 2011
WAM-4	21320	Garuda	Arakkonam	Plinthed at Rail Soudha, SWR HQ, Hubli
WAM-4	21380	Navchetna	Asansol	Scrapped
WAM-4	21399	Anant	Bhusawal	Scrapped

Preserved Examples

As increasing numbers of WAM-4 have been retired, some have found their way into museums or other uses.
A few WAM-4 locomotives have been preserved by Indian Railways at various location around India.

Class	Loco Number	Previous shed	Name	Livery	Location	ref
WAM-4	20400	BIA		BIA cream/orange with blue stripe	Used at Electric Loco Training Center, Uslapur . Reumbered ELTC-120
WAM-4	20472	Ghaziabad			Restricted to shunting/departmental duties only. Earmarked for preservation: I.R. Heritage Website
WAM-4	20484	Bhusawal		BSL cream/orange with orange lining	Loco now preserved at CLW loco park
WAM-4	20601	Jhansi		Maroon with cream band	Earmarked for preservation: I.R. Heritage Website
WAM-4	21320	Arakkonam	Garuda	Red/dark grey/light grey with white line	Plinthed at Rail Soudha, SWR HQ, Hubli
WAG-5/WAM-4B	21101	Tatanagar		Indian Tricolour Livery	Plinthed outside TATA

Locomotive sheds

Former sheds

Technical specifications

Source:

Traction Motors	Alstom TAO 659 A1. Six motors, axle-hung, nose-suspended, force-ventilated.
Gear Ratio	15:62 originally, now many variations, 21:58 being common for WAM-4 6P locomotives.
Transformer	Heil BOT 3460 A, 22.5 kV / 3460 kVA.
Rectifiers	Two silicon rectifier cells, 1270 V / 1000 A each cubicle.
Pantographs	Two Faiveley AM-12.
Hauling capacity
Current Ratings	1100A/10min, 750A continuous

WAS-4

Numbers 21380, 21385 and 21387 of WAM-4 6P were relegated to shunting duty and designated WAS-4.