The solutions to large temperature difference between the shaft and housing of bearings
Due to their design, bearing arrangements often have an inner ring temperature that is higher than the outer ring temperature. For example, the shaft in an electric motor is relatively warm, causing the inner ring to expand. The motor covers that contain the bearing outer rings have a rather large surface area that promotes heat dissipation, making the temperature difference quite substantial.
A large temperature difference between the shaft and housing reduces bearing internal clearance, which can result in too little clearance or even preload, causing high operating temperatures.
What to do?
- Check the shaft and housing temperatures closest to the bearing.
- If justified, select a bearing with increased internal clearance to prevent preloading, e.g. CN to C3, C3 to C4, etc.