Electric Motor Bearing Types and Characteristics

A bearing is a machine element used to permit a rotary motion and transmit the power between machine parts. Rolling element bearings​ allow relative movement of joined two parts: inner and outer rings that move in opposite directions and are separated by rolling elements.

 

 

Bearings can be chosen according to their main dimensions:

 

 

Rolling element bearings play a crucial role in many fields such as the electronics industry, chemical and pharmaceutical industries, wind turbines, airplanes, steel industry, automotive industry, and household appliances. Over 50 billion rolling bearings have been produced across the world. In these fields, a significant part of rolling bearing "consumers" are electric machines, and the technical progress mainly depends on their durability, reliability, and efficiency.

This article aims to discover the main electric motor rolling bearing types, their role in electric motors, and maintenance tips.

 

The main functions of Rolling Bearings in Electric Motors:

• supporting and locating the rotor

• transferring loads from the shaft to the motor frame

• keeping the air gap small and persistent. 

• saving power

• minimizing friction

• enabling high and low-speed operations

 

The main design and utilization requirements of Rolling Bearings in Electric Motors:

• lower production cost

• easy maintenance: easy to handle and maintain

• electric insulation

• low noise

• durability

Electric machinery's most common rolling bearing types are deep groove ball bearings, cylindrical roller bearings, and angular contact ball bearings due to their versatility and overall performance.

 

Deep Groove Ball Bearings

They are characterized by having deep raceway grooves in which the inner and outer rings have circular arcs of a slightly larger radius than that of the balls. They are very effective in high rotating speeds and moderate radial and axial loads. They are used for locating and non-locating bearing positions on small and medium-sized electric motors.

 

Cylindrical Roller Bearings

They are usually used as non-locating bearings on the drive side in medium to large-sized motors.

 

 

Both deep groove ball and cylindrical roller bearings are completely interchangeable with standard bearings!

 

Angular Contact Ball Bearings

They are used as locating bearings in electric motors with high thrust loads or vertical axis and for high rotating speeds. They are available in single or double-row configurations and paired to accommodate thrust loads in both directions.

 

 

Seals in Bearings

They are common in smaller motor applications to significantly limit contamination entry. Unlike open bearings, these bearings are not re-greasable, thus having limited overall bearing life and requiring replacement upon any signs of issues.

 

 

Shielded Bearings

These electric motor bearings can be re-lubricated without any relief; otherwise, pressure can build up and force the shield against the cage or rolling elements.