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Case study

Reducing the failure rate of wind turbine gearboxes



Wind turbine filtration provider




Renewable energy


OEM oil lubricant filter


Gearbox lubricant filtration

Value added

Longer filter life and reduced costs


A global supplier of filtration solutions for wind turbines approached us to support their work on turbine gearboxes. The gearbox is the hardest working part of a wind turbine, transferring the energy produced by the blades through to the generators. The typical working life of a turbine is 20 years, but this is often compromised by gearbox failures.

Up to 50% of gearboxes fail in the first few years of operation, which leads to expensive repairs and lost revenue from unexpected downtime. This is especially true offshore where turbines are much more difficult and expensive to access.

One way to prevent these failures is having high quality hydraulic oil to lubricate the gearbox. To maintain quality, the oil needs filtering.

wear on gear teeth and black particulate in oil.

Images show wear on gear teeth and black particulate in oil.

The problem

Substantial temperature variation caused by weather changes the viscosity of hydraulic oil in gearboxes. Pushing high viscosity oil through filtration media can cause it to flex and deteriorate. Glass microfibre media is often used as it's efficient and has a good flow rate, but it's more susceptible to fracture if flexed. This leads to reduced efficiency and in some severe cases, the oil will bypass the media and remain unfiltered. Particulate contamination in the gearbox will cause it to wear and eventually, fail.

Our client was finding this damage on their pleated filters during servicing and maintenance. They tasked us with finding a solution to reduce the movement of pleats during turbine operation.

The solution

We developed a bespoke melt blown structure to add to the customer's existing filter pleat pack. This structure prevents the pleats from flexing, especially in cold weather and during turbine start-up where oil is most viscous. Another benefit is that this structure prefilters the oil, protecting the pleated media.

diagram of a melt blown filter


The innovative technology:

  • Increases strength with drainage layers bonded to the pleats
  • Prevents pleat movement
  • Reduces damage to glass fibre (GF) media
  • Guarantees pleat separation
  • Maximises surface area
  • Minimises pressure drop
  • Prevents drainage layer from separating from the coalescing layer


Since implementing the solution, our client hasn’t reported any filter damage during routine maintenance. This is an excellent result, and we’re thrilled to have helped extend the life of gearboxes and save money on upkeep.

Our innovative technology used to solve this problem now has a European patent, too.

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