On July 10, a 17-megawatt direct-drive floating offshore wind turbine was successfully rolled out in Fuqing, Fujian province. This marks a global milestone, representing the world's largest single-unit power output and rotor diameter among all direct-drive floating offshore wind turbines to date.

Notably, the turbine is the first of its kind to utilize domestically produced large-diameter main shaft bearings, developed independently by Luoyang Bearing Research Institute Co., Ltd. (ZYS) — a subsidiary of Sinomach.

The bearings produced by ZYS [Photo/ZYS]

The main shaft bearing is a core component in offshore wind turbine systems. Due to its large size and stringent precision requirements, it must withstand complex loading conditions and intense marine corrosion. With high installation and maintenance costs, especially for ultra-large floating turbines, the bearings must meet extremely demanding reliability standards to ensure a service life of 25 years — posing significant R&D and manufacturing challenges.

The 17-MW turbine's main shaft bearing developed by ZYS features two sets of single-row tapered roller bearings, with a maximum outer diameter of 3,425 mm. During development, the company carried out extensive contact fatigue life tests, established a comprehensive transmission chain simulation model, and refined over 100 design iterations to optimize bearing contact angles and the dimensions of rolling elements.

In collaboration with Tsinghua University, ZYS also achieved breakthroughs in surface coating technologies to address electro-corrosion and white etching cracks — two critical issues in large wind turbine bearings. These advances ensure stable, long-term performance in harsh offshore environments.

In recent years, ZYS has positioned itself at the forefront of wind turbine bearing innovation. The company has successively developed the first domestically produced full-range gearbox bearings for 8-MW turbines, as well as main shaft bearings for 7-MW, 10-MW and 18-MW turbines. It also led the development of the world's first 26-MW main shaft and gearbox bearing systems.

The successful creation of the 26-MW bearing series set a new global benchmark for maximum single-unit capacity in wind turbine bearings. These achievements represent major strides in China's independent control of core wind power components and contribute significantly to the security and resilience of the national energy equipment supply chain.