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Gear case in advanced composites for railway locomotives

News International-French

17 Aug 2011

The Indian Railways (IR) already has approximately 3,500 diesel locomotives and 2,500 electric locomotives serving the nation, and some 300 diesel locomotives and 200 electric locomotives are manufactured in different plants every year. At six gear cases per locomotive (one for each axle), 18,000 gear cases on the existing population of operational locomotives will eventually need to be replaced, added to the 3,000 gear cases per year, at least, needed to equip newly manufactured locomotives.

(Published on July 2006 – JEC Magazine #26)




The need for a new type of gear case had arisen from problems the railways were facing with the existing gear cases, manufactured using S-42-S mild steel. Gear cases made of steel are very heavy - nearly 126 kg - and therefore repairing, maintaining, mounting and dismounting them are difficult. Other problems are that steel is susceptible to corrosion; the gear case mounted on the traction motor rests on three bosses, meaning that the heavy weight of the gear case may lead to detachment from the motor in the event of any violent vibration or impact; and the expensive lubricating cardium compound can leak out from various joints and openings in the gear case.



Organisations involved in the project


Bharat Heavy Electricals Ltd. (BHEL), Bhopal, India, is one of the largest public-sector enterprises in India to manufacture a wide range of heavy power engineering products and equipment, including power transformers, generators, switchgears, various types of motors (including traction motors) and diesel locomotives. Its largest plant is in Bhopal.


BHEL chose Permali Wallace. Pvt. Ltd. (PWL) as industry partner for the new project. PWL, which is located very close to BHEL, has been BHEL’s supplier of composite and insulation materials for over 40 years, and the two companies have carried out a number of joint development activities in the past. The need for a new type of new gear case was initially identified when BHEL’s Traction Motor Division, which currently manufactures and supplies diesel locomotives to Indian Railways, discussed the above-mentioned problems with PWL engineers.


For the development of a suitable material for the project, BHEL contacted a materials development specialist also located in Bhopal, the Regional Research Laboratory (RRL). RRL, which is under the Council of Scientific and Industrial Research (CSIR) Department, is one of India’s leading research laboratories.


Once a detailed preliminary analysis was completed, the project was presented to the Advanced Composites Mission (ACM), which approved it and then promoted it to Indian Railways. The ACM, which works on developing marketable, sustainable new products, is a component of the Technology Information Forecasting & Assessment Council (TIFAC), an autonomous organisation under the government of India’s Department of Science & Technology.


Corrosion resistance Susceptible to corrosion Non-corrosive
Reparability & maintenance Difficult - due to greater weight Easy - due to lower weight
Weight per loco (4906 type) 134 x 6 = 804 kg 55 x 6 = 330 kg
Impact resistance Very good Good
Quality of welded joints Sometimes unsatisfactory Jointless construction
Fitting problems Possible, due to deformation during welding Moulded part ensures standard fit
Heat dissipation Very good Design proven through several years of trial and temperature monitoring
Conformity with specification May vary from one part to another Consistent quality, to specification
Risk of gear case falling High / Could lead to derailment if entangled in the gear Very low / Crushable part not liable to cause accident
Fitting time / Manpower Time-consuming / Requires additional accessories, e.g. crane Rapid / Requires only two people
Dimensional stability Poor Good
Oil leakage cost High Negligible
Life cycle cost High Low


An Advisory & Monitoring Committee (AMC) was formed to monitor the progress of the project. This AMC comprised a member of the Railway Board; senior officials from Motive Power Directorate of Research, Development & Standards Organisation (RDSO), and the Indian Railways; senior officials from Chittaranjan Loco Works, a railway production factory that manufactures electric locomotives, and from BHEL; officers from TIFAC; and involved RRL and PWL personnel. Regular meetings were held to expedite the project.


Field trial, modifications and progress


Initially, six gear cases (one locomotive set) were manufactured and sent for field trial to the Mughalsarai Loco Shed, where they were fitted on a diesel engine and monitored for four years. It was also suggested to carry out a temperature trial on the cardium compound. To that end, one FRP gear case and one steel gear case were fitted with a thermocouple on a locomotive to monitor and record the temperature of the compound. It was found that temperature rise in the FRP gear case did not exceed the required maximum temperature and was in line with that obtained on the steel gear case.


On satisfactory completion of the mini field trial, PWL received an order for 60 gear cases (10 locomotive sets) from RDSO, to be supplied to the Jhansi Diesel Loco Shed for extensive field trials.


It was also decided to design and manufacture Hitachi-type gear cases, both for electric locomotives to be supplied to CLW, for which PWL received an order for six sets, or 36 units, and for traction motor type TM-4907 for diesel locomotives being manufactured by BHEL, for which PWL received an order for 18 sets, or 108 units.


After the wiper ring component (also originally in mild steel) was developed in FRP, tested for various parameters, and found to meet all requirements, it was produced in FRP for some of the 4906-type lots and all of the 4907-type lots. This led to further weight reduction.


RDSO received its 60 gear cases in December 1999. These were fitted and subjected to an extensive field trial. Since then, the gear cases for the other designs have also been manufactured and supplied.


Comparison: FRP gear case vs. steel gear case


Using actual performance data received from the users, we were able to establish the following comparison (table).


Project status


CLW has ordered and received 36 Hitachi-type units for use on electric locomotives. So far, the performance is reported to be excellent. BHEL has received another 108 units for 4907-type traction motors. TIFAC has declared the project to be a success, and has recommended the new gear cases to the Indian Railways for regular use.