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Railway lubricant was first invented in the late 1800s by Elijah McCoy. Ever since, scientists have been working on developing several new rail lubrication techniques and effective lubricants for smooth and reliable railway operations.
In general, lubrication can be divided into three regimes, namely, full-film, mixed, and boundary lubrication. In full-film lubrication, the surfaces in contact are totally separated by a lubricant. When the lubricating film is not adequately thick compared to the surface’s roughness, it is known as mixed lubrication. Therefore, in this regime, the friction increases when more asperities get in contact. For the boundary lubrication regime, the lubricating film is not sufficiently thick compared to the surface’s roughness. The key objective with this lubrication regime is to reduce both wheel and rail wear, which in turn would reduce energy usage and sometimes lessens noise.
Importance of the Application of Lubricants on Railway Tracks
Extended rail life
One of the most important functions for which lubrication of railway tracks is important is the minimization of friction between the wheel flange and rail interface.
Lubrication is extremely important in the curves in the railway tracks, where side cutting of rails often occurs. If the rail tracks are unlubricated, the longevity of the rails will suffer, and they will need to be replaced frequently. Regular rail lubrication increases the longevity of these rails.
A study from Railway Tie Association has revealed that the act of lubricating railway tracks could reduce rail wear by a factor of 100 when compared with the unlubricated railway tracks. However, under real conditions, the lubricated rails can endure approximately twice the tonnage of an unlubricated rail before requiring any replacement. The potential life span of the rails can be increased significantly by lubrication. This report revealed the importance of routine rail lubrication as per its maintenance regime.
Decrease in fuel consumption
Studies have shown that the use of rail lubrication improves fuel economy manifold and significantly reduces the annual fuel cost.
The average fuel consumption for trains running on unlubricated rail is 5900 gallons of fuel per million gross tons (MGT). On the contrary, researchers found that trains running on lubricated rail consume 31% less fuel, i.e., 4100 gallons per MGT.
A similar study conducted by the Federal Railroad Administration, where top-of-the-line rail lubrication systems were used, reported an average fuel saving of 7.7%.
Reduction in noise
Another important attribute of rail lubrication is noise reduction.
Maintenance benefits
Lubrication reduces labor costs and extends repair intervals.
Other operational benefits
Lubrication reduces unplanned downtime, increases the reliability of equipment, and reduces the risk of derailments.
Negative Effects of Lubricants on Railway Tracks
Lubricants are used to reduce wear and tear. The use of the wrong lubricant can also have a negative effect. For example, if the lubricant settles down to the rail ball, it will reduce friction. Lubricants can also cause crack tip pressurization.
Different Methods of Lubrication in Railways and their Importance
In the world’s railway system, three different methods are used for lubricating the railway tracks. These are:
- Wayside
- On-board and
- Hi-rail lubrication
Wayside lubrication system
This is the most popular method of rail lubrication. This system of lubrication allows a consistent and controlled volume application of lubricants on the rail. They hold grease or friction modifier in place, allowing the wheels to grab and carry it around the track curve. Some of the advantages of the wayside lubrication system with drilled channels are no clog lubrication, cost-effective, and accurate metering of grease.
On-board lubrication systems
In this system of lubrication, two lubricants are used, for example, grease and solid stick. The spray grease system is the most commonly used method of rail lubrication across Europe where lubricants are applied in a thin layer by direct contact. Two of the advantages of an on-board lubrication system are easy maintenance and inspection.
Hi-rail lubrication
This system of lubrication uses a sophisticated mobile truck for grease application via a nozzle, which allows a thin bead of lubricant along the rail gauge face.
Some of the Commonly Used Lubricants in the Railway Tracks
Interflon lubricants
Interflon lubricants are used to maintain Network Rail tracks. Interflon has successfully devised a technology to lubricate (Interflon Lube EP) without dismantling them. This significantly saves time as previously such maintenance would require several months. After Interflon Lube EP penetrates the joints, it provides a long-term low friction coating, which, in turn, improves the performance of the joint by reducing the friction by 91%. Application of another product along the switch rail, i.e., Interflon Grease OG, a hard-wearing transparent coating, makes inspection for defects easier and keeps the rail well lubricated.
SKF and Lincoln automatic lubrication systems
Thousands of trains operate smoothly owing to SKF and Lincoln automatic lubrication systems. SKF EasyRail on-board systems provide flexibility with variable setting options for railway operators and are highly effective.
DropsA lubrication system
Track‐Lube is a lubricating system that is highly effective for the rail curve. This is a reliable system that can withstand severe environmental conditions and whose control system is connected to a network connection, such that it can communicate with a remote laptop, PC, or PLC (programmable logic controller).
Reference and Further Reading
Vantiegham, E. (2017). Why rail lubrication is vital? [Online] Available at: https://blog.midwestind.com/why-rail-lubrication-is-vital/
Interflon.com, (2021). A new revolution in rail maintenance. [Online]. Available ta: https://interflon.com/industries/rail
Waara, P. (2006). Lubricants Influence on Wear in Sharp Rail Curves. Luleå University of Technology.
Skf.com, Lubrication solutions for rail applications. [Online]. Available at: https://www.skf.com/uk/industries/railways/products-and-services/lubrication-systems
Railsystem.net, (2021). Railwheel lubrication. [Online]. Available at: http://www.railsystem.net/rail-wheel-lubrication/
DropsA.com, (2021). Track lubrication system. [Online]. Available at: https://www.dropsa.com/en/industry/rail-lubrication-system
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