Bearings

# Mastering the Mechanics: All About Thrust Ball Bearings

by Kevin Sweeney
16 August, 2023

## Fundamentals of Thrust Ball Bearings

A cage contains the balls while the grooved aligning seat washers guide them. Washers that have the shaft centered through them are called “shaft washers” and washers installed in  the housing are called “housing washers.” Single Direction thrust ball bearings can take thrust or axial loads in a single direction . Double Direction ball bearings  are bi-directional. Thrust ball bearings with aligning seat washers help reduce the effects of mounting errors.

Thrust ball bearings are sometimes referred to as axial deep groove ball bearings versus the standard radial deep groove ball bearings which accept both radial and axial loads. It is important to understand that axial and thrust loads are different words for the same concept. They both refer to loads acting parallel to the axis of the shaft. The importance of thrust ball bearing design lies in the concept of use for  axial loads only. See below the comparison of axial deep groove ball versus radial deep groove ball bearings.

## Types and Variations of Thrust Ball Bearings

To meet the diverse application demands, a range of thrust ball bearings with distinct designs and characteristics are available.

### Single-Direction Thrust Ball Bearings

Single-Direction Thrust Ball Bearings are engineered to withstand axial loads in one direction only. Their design includes a grooved shaft washer, a flat housing washer, and a set of balls captured by a cage. Variations of this design allow for two flat washers, two grooved washers or one grooved and one flat washer. Due to their simplicity and cost-effectiveness, engineers frequently employ single-direction thrust ball bearings in applications where unidirectional thrust forces are prevalent.

The bearings are not self-retaining; the ball and cage assembly and bearing washers can therefore be fitted separately. In addition to the series with flat washers, series are also available with spherical housing locating washers for the compensation of static angular misalignment. These designs are normally used in conjunction with seating washers. Common uses include automotive transmissions, electric motors, and compact industrial machinery.

Applications for Single Direction

Applications for Single Direction thrust ball bearings include printer peripheral equipment, ball screw support sections of precision positioning stages, automatic guided vehicles (AGVs), radial drilling machines, and fishing reels.

### Double-Direction Thrust Ball Bearings

Their symmetrical design features two grooved shaft washers, two flat housing washers, and a set of balls retained by a central cage. This configuration allows bidirectional support, making them ideal for scenarios where thrust forces may act in opposing directions. These bearings find extensive use in heavy-duty industrial machinery, large-scale power transmission systems, and high-speed aerospace applications.

Applications for Double Direction

Applications for Double Direction thrust ball bearings include vacuum pumps, disc hubs in agricultural machinery, compressors, press machines, and clutch breakers.

## Tapered roller thrust bearings

Tapered roller thrust bearings are designed to accommodate heavy axial loads and peak loads. The bearings are very stiff and are a compact design being able to fit into a small axial space.

#### Features and benefits

Tapered Roller Thrust bearings are of a separable design.The shaft washer and housing washers and the roller with cages can be mounted separately.The roller end design and surface finish on the flange promote lubricant film formation, resulting in lower friction. This also reduces frictional heat and flange wear. Depending on the design,the rollers being crowned or logarithmic raceway profiles optimize the load distribution along the contact surfaces, reducing stress peaks at the roller ends, and reducing the sensitivity to misalignment compared with conventional straight raceway profiles.

Enhanced operational reliability is due in part to the surface finish on the contact surfaces on the rollers and raceway supports in combination with the  formation of a hydrodynamic lubricant film. High load carrying capacity is possible due to the close toleranced manufacturing process.

The rollers incorporated in SKF tapered roller thrust bearings are manufactured to such close dimensional and geometrical tolerances that they are practically identical. This provides optimal load distribution and enables the bearings to accommodate heavy axial loads.

## Specialized Thrust Ball Bearings:

1. High-Temperature Thrust Ball Bearings are engineered to endure elevated temperatures. These bearings incorporate advanced heat-resistant materials, specialized lubricants, and advanced heat dissipation techniques. They excel in applications such as industrial ovens, kilns, and automotive exhaust systems where temperatures can reach extreme levels.
2. High-Speed Thrust Ball Bearings are designed to withstand the challenges of high rotational speeds. These bearings feature optimized cage designs and materials to minimize friction and reduce centrifugal forces. They find crucial applications in high-speed machining centers, turbochargers, and centrifugal compressors.
3. Heavy-Duty Thrust Ball Bearings are built to handle substantial axial loads and shock loads, heavy-duty thrust ball bearings are deployed in rugged industries like construction, mining, and marine operations. Reinforced cages and robust materials ensure their reliability and longevity under harsh operating conditions.

## Applications in Engineering Systems

• Automotive Sector
In automotive applications, thrust ball bearings are essential components in power transmission systems, clutches, and differentials. Their ability to manage axial loads precisely ensures smooth gear shifts and efficient power transfer, contributing to improved vehicle performance and fuel efficiency. Case studies demonstrate how properly selected and installed thrust ball bearings optimize drivetrain performance, resulting in enhanced vehicle handling and reduced maintenance requirements.
• Industrial Machinery
Industrial machinery heavily relies on thrust ball bearings for various applications, including pumps, compressors, and power transmission systems. In these scenarios, these bearings efficiently handle axial loads, ensuring stable and reliable machinery operation. Case studies highlight the use of thrust ball bearings in enhancing industrial equipment performance, reducing downtime, and increasing overall productivity.
• Aerospace Engineering
In the aerospace industry, thrust ball bearings play a critical role in flight control surfaces, aircraft landing gear, and auxiliary power units. Their ability to handle axial loads with minimal friction ensures the safety and efficiency of flight operations. Real world examples demonstrate how thrust ball bearings contribute to the reliability and precision of aerospace systems, where even the slightest improvement can have significant impacts on flight safety and fuel consumption.

## Conclusion

Сomprehensive understanding of the fundamentals, types, applications, and limitations of thrust ball bearings empowers engineers to make informed decisions and achieve optimal performance in  all kinds of applications.

Buy thrust ball bearings from Pacific International Bearing Sales on our online store.

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Kevin Sweeney

Founder and CEO at Pacific International Bearing Sales Inc (PIB)
Education: BS Business and Economics California State University Hayward Ca
CBS (Certified Bearing Specialist)

My role with Pacific International Bearings (PIB) is currently CEO. Since 1976, I have been deeply involved in the bearing industry, working in manufacturing sales at NTN Bearing and subsequently in Bearing Distribution. Before establishing PIB in 1990, I gathered valuable experience in bearing manufacturing and distribution. The last 45 + years in the bearing industry have been both rewarding and challenging, assisting customers across a large number of diverse bearing applications.
Outside of the bearing industry, my interests are family, woodworking, motorcycling, cars, gardening, and golf.