After the success of the first push-pull commercial train service – the 22221/22222 Mumbai Hazrat Nizamuddin Rajdhani Express – IR has decided to increase the number of trains that will run with this configuration.
The move is expected to help increase average speeds of existing Rajdhani and Shatabdi trains. Push-pull rakes may soon be rolled out on trains like the Mumbai Central – New Delhi and Howrah – New Delhi Rajdhanis.
Trials have already been conducted by Central Railway (CR) to convert the 12127/12128 Mumbai – Pune – Mumbai Intercity to a Push-Pull configuration. The targeted schedule of 2 hours 35 minutes was achieved in the trial run.
If the application of such a schedule is found practical on regular runs, the push-pull configuration may result in a saving of 35 minutes for the service. That is a saving of approximately 18% of the original run time.
Guidelines issued for standardization
To create the infrastructure required, detailed guidelines have been issued to various departments to ensure that the rolling stock and locomotives are ready. The current version of the push-pull operation system utilises a 22-core cable laid for the purpose along the train to convey instructions to the rear locomotive.
LHB coaches are now required to be provided with a redundant cable system to ensure that in case one cable fails, operation can continue on the other cable. The cables between coaches are connected using flexible pieces and an arrangement called the Inter-Vehicular Coupler (IVC).
For reliability, the whole cabling system and the IVC arrangement will be waterproof and weatherproof. The cables and the IVC arrangement will be as per international standards.
Based on feedback received from the existing Rajdhani Exp. running with push-pull configuration, the software in the locomotives may be further tweaked to improve performance and reliability of the system.
One of the important hurdles in push-pull was the negotiation of neutral sections. This has been successfully addressed by introducing an automatic system wherein the rear slave loco negotiates the neutral section without any intervention by the driver.
Scope for improvement
At RailPost, we aim to put forth ideas which can deliver benefits to the Indian Railways and its users. In this regard, a few suggestions for the push-pull operation of trains are attached herewith:
Ideally, trains that run on relatively flat terrain should get a WAP-5 class locomotive. Trains running in sections with steep gradients and ghats should be allotted WAP-7. As has been discussed earlier, (TRS article link here), it is better to run the WAP-5 locomotive for higher speed trains as this type of loco produces relatively lower stress on the tracks. On the other hand, the WAP-7 loco will deliver relatively higher stress at the same speed.
However, IR may hit an administrative hurdle.
At present, IR is aiming for utilisation of HOG (Head On Generation) to the maximum extent possible. With HOG, power supply for the train’s hotel load is provided by the locomotive itself. This is supposed to reduce net energy consumption. The other system for the supply of power is the EOG (End On Generation) system, where the supply to the train is provided by diesel generator cars.
While the recently manufactured WAP-7 locos all fit for HOG operations, the higher speed capable WAP-5 locos do not have this facility, except for two prototype units. Hence, if IR wants to run Push-Pull trains with WAP-5s, they will need to manufacture many more HOG enabled units.
This may also be a blessing in disguise. The locomotive can also be slightly redesigned for push-pull operation. The following improvements can be incorporated into the new design:
- The cab permanently facing the train can have its control desk and other equipment removed. Space can be utilised for a toilet for the crew or provision of the Hotel Load equipment.
- The end of the loco which faces the train can be rendered into a flat shape coupled close to the train which will reduce air drag at higher speeds.
- The Push-Pull control scheme can be further expanded by providing a remote monitoring console for the slave locomotive in the master locomotive. The DDS (Driver’s Diagnostic Screen) for the slave loco can be placed in front of the assistant driver’s seat so he can easily monitor the slave loco and even attend certain kinds of faults while comfortably sitting in the master loco. At present only a few indications from the slave loco are displayed in the master loco.
- The working cab profiles of the locomotives can be lengthened a little to make them more aerodynamic.
While the above modifications may require validation trials of the locomotive due to weight redistribution, the end result by way of reduction in energy consumption and an increase in average speeds of these trains can be substantial.