Abstract
The growing demand for renewable energy has made wind turbines increasingly large and
complex. Demand for efficient main bearings optimized to endure dynamic and unpredictable
stresses while allowing turbine motion rises even more. Over the years, rolling element bearings
have advanced to meet this demand, driven by innovations from industry and academia. This
study examined industry-related and academic contributions to the advancement of wind turbine
main bearings. Spherical and tapered roller bearings are identified as the basic wind turbine rotor
bearings. From the works reviewed, it was found that industry-related contributions on these
bearings center on bearing configuration improvements, cage improvements, the development of
improved coats, and the design of novel evolutionary variants of the bearings. The SKF was
identified as having contributed more to the development of wind turbine rotor bearings with the
patenting of two novel bearings: the CARB toroidal bearing and the Nautilus. Scholarly contributions
have majored in bearing geometry and profile optimization. Tapered roller bearings were
found to have received more research attention than spherical roller bearings. Also, few innovative
studies on CARB toroidal bearing, asymmetrical spherical roller bearing, and the Nautilus
have been reported. Exclusively theoretical analyses have been mostly used in performance optimizations
of the bearings. Only in a few studies did experimental investigations validate theoretical
findings, creating potential avenues for experimental studies. Insights from the review
indicate that tapered roller bearings or plain bearings could be viable substitute for spherical
main shaft bearings, considering their persistent reliability challenges. The authors recommend
more exploration of evolutionary bearing optimization techniques, more investigations on
bearing lubricants, housing material, cage material, and coating material designs, and increased
industry-academic engagement to pave the way for more main bearing innovation.