Since electric motors are designed and used differently in many different industries, there are many different electric motor bearings types used to support them.
Most electric motors in industrial facilities consist of rolling element bearings, either ball bearings or roller bearings. We will explore these different motor bearing types and sealing methods in this article.
Used in direct coupled applications. These can handle axial as well as radial loads.
For belt applications, typically for motors 150 HP and above. The motor needs radial load, and cannot withstand axial load.
Sealed Bearing
Typically used in smaller motor applications. These greatly limit the ingress of contaminants. These bearings are not relubricatable, thus eliminating the need for relubrication, but will limit the overall life of the bearing. These bearings have a limited life and will need to be replaced at any sign of trouble.
Shielded Bearing
These bearings restrict contamination from getting into the rolling elements at installation and during operation. The shields help to retain the lubrication into the bearing chamber. The balls are re-lubricated with packed grease by the slinger which feeds the inner race. These can be re-lubricated but without any relief, pressure can build up and force the shield against the cage or rolling elements.
Open Bearing
These bearings are not shielded or sealed therefore they minimize friction and allow for cooler bearing operation. With proper reliefs in place, these bearings can be easily re-lubricated. However, with limited protection from contamination the entire bearing system must be designed to protect the bearing itself from contamination as well as designed to contain the grease in the bearing cavity.
Bearing Isolator
Sometimes referred to as an Inpro/Seal(R), a rotating labyrinth seal is designed to protect the bearings. Before dirt, water or other contaminates can get from the atmosphere to the bearing it must pass through a labyrinth where it is subjected to centrifugal and gravitational forces. Contaminants are collected in a groove where it is expelled back to the atmosphere through a port in the motor's stator. With a labyrinth seal installed with open bearings, the bearing is re-greasable as well as protection from environmental contamination.
At Hebei Nicer, we want our customers and clients to be well educated in their options. Bearings can be a major point of failure and frustration for end-users when the correct bearing is not used. That is the main reason we continue to as Why we introduce motor bearing types to you.
