POWERTRAIN


BEARING THE


BRUNT OF


Chris Johnson explains how to choose the right bearings for the job


E


MARINE CONDITIONS


lectric boats are gaining ground – even on water. Future boat companies are committing to some form of


electrification in boats, with one being named as the ‘Tesla of the sea’ along with its founder, Konrad Bergström, hailed as a nautical Elon Musk. Given the extreme conditions,


it is easy to assume that choosing a bearing made out of a harder material, such as chrome steel, would ensure the best bearing performance. However, because of sea water’s extreme corrosive power, a compromise between load capacity and corrosion resistance is required to maximise the lifespan of bearings. Bearings used in many marine applications, including electric motors, are often made from less corrosion-resistant materials, such as 440


grade stainless steel, due to its low noise and low vibration


properties. However, these bearings need to have added protection from seawater contact in order to extend their useful life. The standard approach to minimise corrosion risk in these bearings is to use housings or end caps, and a packing of grease to shield steel bearings from the


Chargers are increasingly common for cars, why not for boats too?


20 www.engineerlive.com


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