How Bearings Work

Have you ever wondered how electric motors and many types of industrial equipment spin so smoothly, quietly, and efficiently? The answer is found in a neat, simple little device called a bearing. Without bearings, maintenance personnel would be constantly replacing parts that wear out because of friction.

06/01/2001


Have you ever wondered how electric motors and many types of industrial equipment spin so smoothly, quietly, and efficiently? The answer is found in a neat, simple little device called a bearing. Without bearings, maintenance personnel would be constantly replacing parts that wear out because of friction.

This column explains bearing basics and looks at several different types.

Bearing basics

The concept behind a bearing is very simple: Items roll better than they slide. The reason for the improved performance is that when items slide, friction between the two causes a force that tends to slow them down. But, if the two surfaces roll over each other, friction is greatly reduced.

Bearings reduce friction by providing smooth, metal balls or rollers, and a smooth inner and outer metal surface for the balls to roll against. These balls or rollers "bear" the load, allowing the device to spin smoothly.

Bearings typically deal with two kinds of loading: radial (illustrated below) and thrust. Radial loading is perpendicular to the bearing's axis or rotation, while thrust loading is along the axis of rotation. Depending on where the bearing is used, it may see all radial loading, all thrust loading, or a combination of the two.

Types of bearings

There are many types of bearings, each with a different purpose. Common configurations include ball, roller, needle, ball thrust, and roller thrust.

Ball bearings (left) are probably the most common type. They are found in everything from inline skates to hard drives, and handle both radial and thrust loads. They are usually used in applications where the load is relatively small.

Ball bearings transmit the load from the outer race to the ball, and from the ball to the inner race. Since the ball is a sphere, it only contacts the inner and outer race at a very small point, which helps it spin very smoothly. But this condition also means that there is not much contact area holding the load. Therefore, if the bearing is overloaded, balls can deform or squish, ruining the bearing.

Roller bearings (below) are used in applications such as conveyor belt rollers, where they must hold heavy radial loads. In these bearings, the roller is a cylinder, so the contact between the inner and outer race is not a point but a line. This arrangement spreads the load out over a larger area, which allows the bearing to handle much greater loads than a ball bearing. However this type is not designed to handle much thrust loading.

Needle bearings are a variation of the roller type. They use cylinders with a very small diameter, which allows the bearing to fit into tight places.

Ball thrust bearings are used primarily for low speed applications, and cannot handle much radial load.

Roller thrust bearings support large thrust loads. They are often found in gearsets, such as between the housing and rotating shafts.





Top Plant
The Top Plant program honors outstanding manufacturing facilities in North America.
Product of the Year
The Product of the Year program recognizes products newly released in the manufacturing industries.
System Integrator of the Year
Each year, a panel of Control Engineering and Plant Engineering editors and industry expert judges select the System Integrator of the Year Award winners in three categories.
GAMS preview, 2018 Mid-Year Report, EAM and Safety
June 2018
2018 Lubrication Guide, Motor and maintenance management, Control system migration
May 2018
Electrical standards, robots and Lean manufacturing, and how an aluminum packaging plant is helping community growth.
April 2018
2017 Product of the Year winners, retrofitting a press, IMTS and Hannover Messe preview, natural refrigerants, testing steam traps
SCADA standardization, capital expenditures, data-driven drilling and execution
June 2018
Machine learning, produced water benefits, programming cavity pumps
April 2018
ROVs, rigs, and the real time; wellsite valve manifolds; AI on a chip; analytics use for pipelines
Spring 2018
Burners for heat-treating furnaces, CHP, dryers, gas humidification, and more
Choosing an automation controller, Lean manufacturing
February 2018
Setting internal automation standards

Annual Salary Survey

After two years of economic concerns, manufacturing leaders once again have homed in on the single biggest issue facing their operations:

It's the workers—or more specifically, the lack of workers.

The 2017 Plant Engineering Salary Survey looks at not just what plant managers make, but what they think. As they look across their plants today, plant managers say they don’t have the operational depth to take on the new technologies and new challenges of global manufacturing.

Read more: 2017 Salary Survey

The Maintenance and Reliability Coach's blog
Maintenance and reliability tips and best practices from the maintenance and reliability coaches at Allied Reliability Group.
One Voice for Manufacturing
The One Voice for Manufacturing blog reports on federal public policy issues impacting the manufacturing sector. One Voice is a joint effort by the National Tooling and Machining...
The Maintenance and Reliability Professionals Blog
The Society for Maintenance and Reliability Professionals an organization devoted...
Machine Safety
Join this ongoing discussion of machine guarding topics, including solutions assessments, regulatory compliance, gap analysis...
Research Analyst Blog
IMS Research, recently acquired by IHS Inc., is a leading independent supplier of market research and consultancy to the global electronics industry.
Marshall on Maintenance
Maintenance is not optional in manufacturing. It’s a profit center, driving productivity and uptime while reducing overall repair costs.
Lachance on CMMS
The Lachance on CMMS blog is about current maintenance topics. Blogger Paul Lachance is president and chief technology officer for Smartware Group.
Material Handling
This digital report explains how everything from conveyors and robots to automatic picking systems and digital orders have evolved to keep pace with the speed of change in the supply chain.
Electrical Safety Update
This digital report explains how plant engineers need to take greater care when it comes to electrical safety incidents on the plant floor.
IIoT: Machines, Equipment, & Asset Management
Articles in this digital report highlight technologies that enable Industrial Internet of Things, IIoT-related products and strategies.
Randy Steele
Maintenance Manager; California Oils Corp.
Matthew J. Woo, PE, RCDD, LEED AP BD+C
Associate, Electrical Engineering; Wood Harbinger
Randy Oliver
Control Systems Engineer; Robert Bosch Corp.
Data Centers: Impacts of Climate and Cooling Technology
This course focuses on climate analysis, appropriateness of cooling system selection, and combining cooling systems.
Safety First: Arc Flash 101
This course will help identify and reveal electrical hazards and identify the solutions to implementing and maintaining a safe work environment.
Critical Power: Hospital Electrical Systems
This course explains how maintaining power and communication systems through emergency power-generation systems is critical.
click me