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How to extend the life of electric motor bearings

Electric motor bearings have three purposes – to support the rotor, maintain a consistent air gap between the rotor and stator and to transfer loads from the rotor shaft to the motor frame. Bearings play a crucial role in electric motor operation but naturally in time they wear away and must be replaced.

However, there are ways to maximise the operational life of electric motor bearings and maintain the efficiency of your equipment. We take a look at a few of them here.


There are many factors that affect the frequency of bearing re-lubrication, such as bearing design, grease type, motor speed and running temperature. It’s advisable to check which grease is currently being used and match it – the manufacturer should be able to advise you on a compatible alternative if necessary.

Achieving the correct balance is essential when it comes to lubrication. Excessive greasing can lead to overheating as the lubricant is churned, while insufficient lubricant increases abrasion and causes premature wear.


Moisture within an electric motor causes corrosion of internal components – including bearings. While the motor is running, the heat generated tends to repel the build-up of condensation, but during downtime moisture is allowed to form.

There are lubricants available containing rust inhibitors, while good-quality seals will help to keep humidity out of bearings. Users can also rotate motor shafts during idle periods to redistribute lubricant which helps maintain bearing protection.


Bearings must be subjected to a minimum load in order for the shaft to rotate, which forms a lubricant film and prevents skidding. Maintaining minimum loads is especially important for motors with high acceleration and speeds around 75% of recommended ratings.

Gibbons Engineering Group offer service and repair for electric motors and most other electro-mechanical devices. Call us on 01621 868138 or email and one of our expert engineers will be happy to help. 

Electric Motors

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