Curved rail lubricants are an essential component of the rail industry, playing a critical role in ensuring reliable, safe operation of vehicles and protecting infrastructure.
While the strain on rail networks to control costs has never been greater, innovative friction management solutions are essential to lessen the time engineers spend on track, reduce maintenance costs to achieve long term savings, whilst also protecting our environment.
Desirable characteristics of a curved rail lubricant
An optimal curved rail lubricant will deliver high levels of performance in each of the areas set out below, and inevitably the higher the performance capability of the lubricant, the higher the cost to the customer. The desired balance between cost and performance will vary according to market and customer requirements; however, it is good practice to assess the through-life costs and benefits of a lubrication system rather than the simple up-front cost of a lubricant.
Low Coefficient of Friction (CoF) – The lubricant should ensure CoF at the wheel/rail interface, typically less than 0.15.
Wide Operating Temperature Range – Desirable to maximise the temperature range over which a lubricant’s viscosity remains consistent, which in turn ensures pumpability through common dispensing systems. Given a wide enough temperature range a single product can be used all year round which is important in environments with wide seasonal variations. Correct viscosity is also essential to avoid pump cavitation, ensure consistent application on demand, and achieve consistent and stable beading from applicator equipment.
Carry Down – The distance from the point of application over which the lubricant remains effective. Generally, the further the carry-down achieved the better, although this characteristic is heavily influenced by factors such as track condition, vehicle axle loading and number of axles over a given period.
Application Rate – Closely linked to carry-down, application rate for a given product to achieve required performance. Ideally, lower application rates are desirable as this can:
Reduce purchase quantities
Reduce the number of applicators needed over a given length of track
Reduce the refill frequency and associated logistics and resource costs
Improve safety by reducing on-track time for maintainers
Good Adhesion and Cohesion – Adhesion means the ability of the lubricant to stick to a wheel or track and cohesion the ability to stick to itself. These are important to minimise the amount of “splash-off” when a train initially picks up lubricant, and “fling-off” from the trains rotating wheels during the carry down phase. Good cohesion also affects a lubricant’s elastic properties and helps minimise the amount of lubricant “squeezed” out of a contact patch under pressure.
Controlled Release of Lubricant – Controlled release of lubricant without excessive oil bleed characterises a grease’s ability to deliver the lubricant in the working zone as well as its stability in storage. Key to this are the thickener structure and content, and also the manufacturing process. Variations in the manufacturing process can lead to significant performance differences between products with similar formulations and are often the basis of proprietary product data. An effective thickener structure remains stable and ensures low oil separation which is important to ensure the lubricant retains its designed performance characteristics over its designed storage life, and also to ensure separation does not occur in applicator tanks. Good cohesion also helps prevent separation.
Extreme Pressure (EP) – Good EP characteristics maximise the wear protection offered by a lubricant under heavy load and are usually achieved by special EP additives and/ or by certain thickener systems. EP performance is indicated by 4 ball weld and/or scar testing although other tests are available.
Corrosion Protection – The lubricant should offer corrosion protection to the rails and wheels.
Wash Off – A further desirable characteristic is good resistance to water wash-off to ensure that the lubricant film is maintained in wet conditions.
Safe Handling – Our rail lubricants are non-hazardous and non-toxic, ensuring the safety of the operators who handle them.
Environmental Factors – Although the importance of the environmental impact of this type of product varies between markets and customers, the fact that these are total loss systems where all the lubricant enters the environment means “Eco Credentials” are becoming increasingly important for many users. In the EU the benchmark performance criteria is EU Ecolabel, although there are a range of other relevant standards such as Blue Angel. A further common test for biodegradability of lubricants is OECD 301b. Care should be taken to fully understand how the claimed Environmental performance of a product meets the environmental requirements of a customer, as widely used terminology with specific meanings such as “Bio-based” and “readily biodegradable” are sometimes used on a generic basis and can be misleading as to how environmentally friendly a product really is.
How is the lubricant applied?
Trackside lubrication:
The first delivery system of rail lubricants is trackside lubrication. This is a delivery system that is designed for application via trackside lubricators positioned at critical points along the railway track to lubricate the gauge corner of rail curves.
Trackside Curved Rail Grease
The EcoCurve Rail Range
On-board spray:
The second is delivered via on-board spray This is particularly suited to sensitive and highly visible urban sites and involves curve-sensing controls.
On-board Spray Lubricants
Solid Stick:
The third one is also an on-board system, delivered via a solid stick. This is a simple and clean system that is easy to maintain.
If you need more information about our guageface lubrication products please talk to us today!
