Chapter 5 - Wind turbine gearboxes: Failures, surface treatments and condition monitoring

Abstract

Approximately 75% of all wind turbines are based on geared designs. Wind turbine gear designs often follow the ISO 6336-5 standard. Gears are typically made from high Cr steel grades such as 4320, 4820, 9310, and 18CrNiMo7-6. These steel grades have low carbon and high chromium and molybdenum content to increase the maximum toughness of the material. Wind turbine gearbox designs have been improving over the years resulting in the continuous revision of the IEC-61400 international standard, which outlines the minimum requirements for specification, design, and verification of gearboxes in wind turbines. Despite these continuous improvements, several technical challenges remain that have yet to be overcome, especially in the case of offshore wind farms. This chapter covers the most common wind turbine gearbox failures, while also providing examples on how to detect and prevent unexpected failures by using appropriate condition monitoring systems and surface engineering treatment techniques, respectively.