In wind farm operations, any bearing failure inside the drivetrain can lead to high repair costs and extended downtime. Failures in the main shaft or generator are among the most costly and time-consuming to resolve. Their bearings operate under tough load and speed conditions. In many cases, replacement requires heavy-lift equipment and long lead times.
Lubrication strategies play a key role in reducing these risks. Selecting greases that match operating conditions, combined with appropriate sealing and monitoring, can help extend bearing life and reduce the frequency of unscheduled interventions.
Main shaft bearings: high loads, low speeds
Main shaft bearings are exposed to variable axial and radial loads at low rotational speeds, often around 10 rpm. These bearings are subject to shaft misalignment, vibration, and temperature variation, all of which can degrade lubricant performance over time.
SKF offers specialised greases for these conditions:
- SKF LGEP 2: A lithium soap-based grease with extreme pressure additives that provides strong corrosion protection and high load capacity, and performs reliably in temperatures from –20 to 110 °C.
- SKF LGWM 1: A mineral oil-based grease designed for combined axial and radial loads with good water resistance, remaining effective across temperatures from –30 to 110 °C.
- SKF LGWM 2: A synthetic mineral oil-based grease with a calcium sulphonate complex thickener that offers excellent mechanical stability, high load resistance, and protection against false brinelling in wet or cold environments, performing reliably in a range from –40 to 110 °C.
Generator bearings: high temperatures and electrical risk
Generator bearings face high rotational speeds, elevated temperatures, and exposure to stray electric currents, which can cause electrical erosion. Effective lubrication helps minimise wear, support long grease life, and protect against damage such as false brinelling and current-related degradation.
Recommended greases include:
- SKF LGHP 2: A premium mineral oil-based grease with a polyurea thickener, offering excellent thermal stability, corrosion resistance, and pumpability across a wide temperature range, remaining effective from –40 to 150 °C.
- SKF LGHQ 2: A modern polyurea-based grease designed for high-speed electric motor applications, offering long grease life, strong mechanical stability, and good low-temperature performance, with proven effectiveness in temperatures from –30 to 160 °C.
Why lubrication choices matter
Main shaft and generator bearings operate under very different conditions, and no single grease can meet both sets of demands. In a typical machine, lubricants account for just 2 to 3 % of running costs, yet poor lubrication causes around 40 % of maintenance costs. That makes grease selection one of the most cost-effective decisions in wind turbine operation.
