A Quick Overview of Rail Track Lubrication

RS Clare & Co.

Which lubricants are used for railway tracks? This article gives you a quick introduction to the different lubricants for rail tracks, including curve rail lubricants, fishplate lubricants, switchplate & switchblade lubricants, and Top of Rail Friction Modifiers.

By Frans Pienaar, Technical Sales Manager

When I started in the lubricant business in 1997, I was given a technical manual by my boss, with over 1,000 pages of finely printed text, illustrations, and diagrams. “After I have read this book, will I know everything about lubricants?” I asked. “When you have read this book, you will know one-eighth of everything there is to know about lubricants,” he replied.

Over 25 years later, I still don’t know everything there is to know about lubricants. But, like me in 1997, we all have to start somewhere. This article is an introduction to rail lubrication for those who are new to the business or want to get a quick overview. But it is just the beginning – your journey into the fascinating world of rail lubricants has only just begun!


The importance of lubricants for higher rail safety and lower costs

When it comes to rail tracks, there are four main lubricant categories: Curve rail lubricants, fishplate lubricants, switchplate & switchblade lubricants, and Top of Rail Friction Modifiers. In all cases, lubrication is a must-have to ensure the longevity, high performance, low noise, and low maintenance costs of rail tracks.

These benefits can quickly be summarised:

Reduced friction: Whenever two metal surfaces interact – such as a train wheel and a rail – you get friction. In some cases, a small amount of friction is needed – for example, so the wheels don’t slide. Lubricants are used to control the amount of friction, so the train moves with the least possible wear, noise, and fuel.

Lower maintenance: Wear of the rail and/or wheels occurs when friction becomes too high. Lubricants lower this wear, increasing intervals between maintenance. As a result, rail operators experience fewer service disruptions and lower maintenance costs (equipment and manhours).

Noise reduction: As with wear, noise is created when two metal surfaces interact. Lubricants reduce this noise by lowering the friction between the two surfaces.

Reduced risk of derailment: Luckily, the instances are very rare, but a train or carriage can run off the rails. Although many derailments are minor, all lead to temporary disruption – and some can result in serious accident. By minimising wear, lubricants are an essential part of the operation to stop trains or carriages climbing off the rails, especially around curves and at junctions.

Now, let’s look at the different types of rail track lubricants.


Curve Rail Grease: What is a Curve Rail?

Curve rail grease is probably the most used rail lubricant, as it’s applied to the rail whenever there is a curve in a rail line. To understand why it’s needed, you need to understand the basics of the wheel rail interface.

Rail lines consist of two rails running parallel to each other. When the line is running straight, the force from the train is vertical – pressing down equally on both rails. However, when the line curves, lateral forces come into play. With most rail curves, you will have a Cant angle (i.e. a low and high rail) to mitigate the lateral forces. In addition, train wheels are cone shaped. This enables the wheel on the high rail to travel a longer distance than the wheel on the low rail when the train negotiates a curve.



The Role of the Lubricant

The Cant angle of each curve is designed taking into consideration the expected train’s weight and speed. If a train exceeds either of these criteria, the flange of the wheel on the high rail will push against the gauge face of the rail, causing wear. (If the train exceeds either criterion too much, it can climb the rails and cause a derailment.) Curve rail grease is applied to the rail gauge face to reduce wear. This not only reduces maintenance requirements on curved rails, but also lowers the risk of derailment due to damages to the rail.


(Curve rail grease is applied to the gauge face of the rail.)


The ideal curve rail grease must:

Have extreme pressure (EP) properties to resist the forces applied to it by the train wheel
Have extreme adhesion properties to ensure it stays in place
Be stable at all operating temperatures
Be resistant to extreme weather, including high rains, snow and heat


Fishplate Grease: What is a Fishplate?

Put simply, a fishplate is a metal plate that is bolted to the side of two rails where they meet, helping hold the two pieces of rail together. Different fishplates are available depending on whether the rails connected are the same/different height or size or need electrical insulation.

The Role of the Lubricant

Fishplate grease is applied underneath the fishplate before it’s bolted to the rails and is extremely important to help extend the lifetime and reliability of the joint. The lubricant allows the rails and fishplate to move easily, so they can accommodate load fluctuations when a train passes over the top or expansion/contraction caused by temperature changes. The lubricant also lowers wear and other damage, such as corrosion.

The ideal fishplate grease must:

Have extreme anti-corrosive properties
Be very long-lasting, ideally extending maintenance/replacement intervals to two years minimum
Not hinder the conduction of electricity
Be stable at all operating temperatures
Be resistant to extreme weather, including high rains, snow and heat


Switchplate Grease: What is a Switchplate?

A switch enables a train to change direction. It’s usually a Y-shaped piece of track, where one-line splits into two. By opening or closing the switch, the operator sends the train to the left line or the right line. The switchplate is a horizontal metal plate that sits below the moving piece of track (known as the switchblade). When the operator opens or closes the switch, the switchblade slides over the switchplate.


The Role of the Lubricant

A switchplate lubricant is applied to the top of the switchplate. Its job is to enable the switchblade rail to move freely, with as little force as possible. This is extremely important because, if a switchblade gets stuck, it can cause severe delays and even train derailment.

The ideal switchplate grease must:

Have extreme adhesion and durability properties so that it stays in place, even during the sliding movement from the switchblade
Be extremely resistant to weather, including wash off from rainfall and UV light, as it is very exposed
Have extreme pressure (EP) properties to handle the forces as the train passes
Be able to resist high and low temperatures, including high temperatures from switch heaters, which are used in some countries to mitigate frost, snow and ice


Top of Rail Friction Modifiers: What are they?

Top of Rail Friction Management is a relatively new rail lubrication field, with a lot of development in recent years. Basically, Top of Rail Friction Modifiers are applied to the top of the rail to ensure there is the ideal amount of friction between the wheel and the rail.

What do Top of Rail Friction Modifiers do?

On a rail track, you want some friction between the wheel and the track, otherwise the wheel will just spin or slide. However, if there is too much friction, you will require more energy to drive the train forward. Top of Rail Friction Modifiers are applied to the top of the track to ensure the ideal friction co-efficient between the wheel and rail. (This is somewhere between 0.3-0.4; on a dry unlubricated rail it is around 0.7.) The result is optimised rail performance, with lower wear, less noise and reduced fuel consumption.

(As the name suggests, Top of Rail Friction Modifiers are applied to the top of the rail.)


Other Considerations: Environmentally Friendly, Heavy Haul or Extreme Weather Lubricants?

There are other considerations when choosing a rail lubricant. For example:

Environmentally friendly products are increasingly specified by regulatory authorities, as lubricant residue can seep into the environment and water table.
Tracks that are mainly used for heavy goods trains may need a heavy haul gauge face grease, formulated to withstand heavy loads.
In tunnels and urban areas, rail greases often need fire resistant properties to reduce the danger of fire and smoke.

In most cases, special curve rail greases, fishplate greases, switchplate greases and Top of Rail Friction Modifiers can all be found with these properties. But the exact lubricant you need will depend on several factors, including regulatory requirements, weather extremes and the rail type and use.

Getting Started: Choosing the Ideal Lubricant for your Needs

If you would like any advice on how to choose the best lubricant for your needs, get in touch with us at RS Clare. We would be happy to help.



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