UPDATED: New 9,000 hp WAG-9 HH Locomotive Rolls Out of CLW

[UPDATE 1: 90001 features Medha propulsion equipment and has been allocated to Gomoh ELS. 90002 has also rolled out, has been allocated to Tatanagar ELS. This unit has propulsion equipment from Siemens. ]

It was an important day for India’s premier electric loco manufacturer; and one that recently became the world’s largest such facility. Chittaranjan Locomotive Works (CLW) turned out its first 9,000 hp WAG-9 freight locomotive on 31st March 2019, the last day of the financial year.

This 9,000 hp version of the WAG-9H has been classified by IR as WAG-9 HH. The first H stands for higher axle load and the second H stands for the higher power rating. The class has been allocated a block of serial numbers starting with 90001, the number of the first unit.

The decision to upgrade the power output of the WAG-9 was taken to partly meet the demands of the upcoming electrified Western Dedicated Freight Corridor (WDFC). The upgraded locomotive class will also augment hauling capacity on the existing network of the Indian Railways.


Normally, a ground-up design of a locomotive involves significant cost as well as a long time frame from the design stage to revenue service.  From the very beginning, the goal was to increase the power of locomotives from 6,000 hp to 9,000 hp.

Excerpt from the final Draft Technical Specification for the 9,000 hp upgraded WAG-9 released in April 2017.

At the same time, to speed up the process, the design team wanted to retain as many of the existing design details of the original WAG-9H as possible. Hence, the brains behind the project chose to go for a tried and tested design already in service on IR. Specifications were laid down to ensure that as many of the existing pieces of equipment are retained as possible.

Upgrades and New Features

Nevertheless, several modifications were required to upgrade the loco to a higher power rating. In addition, several new features have also been introduced in the WAG-9HH.

Excerpt from the final Draft Technical Specification for the 9,000 hp upgraded WAG-9 released in April 2017

One major feature is the addition of a data-logger incorporated into the system. The system will monitor and record all vital parameters of the locomotive and the actions of the crew. The output of the data logger can be used for working improvements and to investigate abnormal events like locomotive failures or  derailments/accidents.

The new WAG-9HH will also have a device to that will enable continuous tracking through GPS. An arrangement to link the device in future to a central server through wireless link, thus enabling real-time remote monitoring and troubleshooting, has been provided.

A third important feature is the use of an open-source software architecture of international standards. This will ensure that IR will not be dependent on third-party vendors supplying proprietary software. IR can freely modify or upgrade the software at any stage of the service life of the locomotive.

WAG-9HH also uses state-of-the-art IGBT technology for power and the auxiliary circuits. IGBTs use a smaller space envelope, have higher power transfer efficiency, lower energy losses, lower heat output, besides simpler firing and control circuits.

All axles will be individually driven, ensuring improved adhesion. Improved adhesion translates into higher hauling power. Individual drive on all axles also ensures that the failure of any individual drive or traction motor will not result in complete loco failure.

The locomotive will also have an upgraded and modified arrangement to ensure better cooling of the equipment. This will enable trouble-free continuous working in the typically Indian high heat and dust environment that these units are going to inhabit.

The locomotive also gets an upgraded traction motor design and strengthened bogies to handle the additional power available.

A new feature not seen so far on any IR locomotive is a Speed Preset. The feature will allow setting of a predetermined target speed by the loco pilot. The locomotive will then continue to accelerate the train till the target speed is reached, within the overall control restrictions that are fed into the software.

However, if the loco is running at a speed higher than the preset speed, braking action will be initiated to bring the speed down to the target level. This feature should help simplify the work of a loco pilot.

Redundancy in the locomotive software, hardware and electrical equipment will be better managed to ensure that the failure of a single sub-system shall normally not result in the complete failure of the locomotive.

More units, and 9,000 hp WAP-7 in the offing?

IR had ordered propulsion equipment for 13 units of 9,000 hp locomotives in late 2017 and early 2018. This includes five units of the proposed 9,000 hp WAP-7 class locomotives. Siemens was awarded the bulk of these purchase orders, followed by Medha and BHEL.

The WAG-9 HH prototype that has been rolled out will now undergo field and oscillation trials. If the results are satisfactory, the class will go into serial production soon after and enter revenue service.

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About the Author: Khalid Kagzi


  1. Great article! What I like 1. Data logger , long time overdue. 2. Provision for remote monitoring in the future. Necessary to improve freight performance.

    What I don’t know :
    need for preset speed?
    What are the benefits?
    How to get around PSR that may be below the preset speed?

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