Types of Thrust Bearings

Thrust bearings are a key component of machines that carry heavy loads, operate at high speeds or are exposed to challenging environments. They are available in a wide range of sizes.

Like other rotary bearings, thrust bearings support axial loads while decreasing friction between parts. They are typically positioned against a high thrust collar around a shaft.

Ball Bearings

Ball bearings are designed to support radial loads and light axial loads. They have a cage or retainer that keeps the rolling elements centered and spaced apart for optimal performance.

They are one of the most common bearing classes. They consist of a row of balls as rolling elements that are trapped between two annulus-shaped metal pieces known as races. When the bearing rotates, the balls roll on the inner and outer races and create very little friction.

The spherical shape of the ball only contacts the inner and outer race at very small points, which helps them spin smoothly. However, this small area of contact also limits their capacity to carry axial loads perpendicular to the axis of rotation. To increase their capacity to handle these axial loads, they must be used in pairs.

Cylindrical Roller Bearings

Designed with a longer bearing length and larger bore diameter than ball bearings, cylindrical roller bearings can handle high radial loads. They also have a greater ability to carry axial loads in one direction, making them well-suited as thrust bearings in many applications.

They also provide better misalignment capacity than a ball bearing, and are available with or without a cage. Single-row designs are typically sub-categorized as NN or NNU models, while double-row configurations are known as NN and NUP models.

The NF, NJ and NUP series of bearings are designed to withstand incidental thrust loads in addition to radial loads. They can also be used as locating or nonlocating bearings. Bearings that are filled with as many rolling elements as can fit—referred to as full-complement designs—are able to support higher basic dynamic and static load ratings, but wear at those speeds is usually higher than for bearings using carriers. The relaunched 2019 Generalized Bearing Life Model offers calculations that take this into account.

Needle Roller Bearings

INA caged needle roller bearings are easy to handle and take up less space than standard thrust washers. Their small size makes them the preferred choice for machine tools and other applications requiring rotational accuracy under heavy loads. Their unique cage structure guides the needle rollers and provides effective lubrication conditions even at high speeds. Cage & roller assemblies also feature controlled contour crowning that reduces stress concentration on the end of the rolling element from moderate misalignment and shaft bending and extends bearing life.

This allows the rollers to disperse contact loads into a larger volume and helps them sustain heavy axial loads. To ensure the long-term reliability of these bearings, they must be properly maintained. Check out our Bearing Maintenance guide to learn more about proper lubrication techniques.

Tapered Roller Bearings

The tapered shape of roller bearings helps them efficiently transfer combined forces and shifting forces within a rotational system. The steeper the gradient of a tapered bearing’s angle, the more thrust/axial load it can handle; however, this reduces its ability to harness radial loads.

Unlike ball bearings, which use point contact, the angled surfaces of a tapered roller bearing’s cones and cups make them ideal for transferring and supporting axial loads. These angled surfaces also prevent stress increases at the edge of the contact points and increase the axial load-carrying capacity of the bearings.

A matched tapered roller bearing consists of an outer and inner ring with tapered raceways, as well as a cage that holds the rollers in place. Single-row tapered roller bearings are not self-retaining and must be adjusted against a second identically sized tapered roller bearing. They are available in both open and closed designs. Open tapered bearings are adjustable, while matched tapered bearings have their operating clearance and preload set at the factory.