What Are Tapered Roller Bearings?

Posted by Bradley Irwin on March 18, 2016

Tapered roller bearings comprise of an outer ring, an inner ring, rollers, and a cage profiled to ensure even distribution of the load. At low to intermediate speeds, they have high axial and radial load capacities.

Tapered Roller Bearings Design

You can find tapered roller bearings in single-row, two-row, and four-row designs.

For the single-row bearings, thrust capacity is around 60 percent of the radial capacity.

The two-row bearings can handle thrust loads in both directions and have a higher radial load capacity.

You can configure the rollers in such a way that contact lines between the race and roller diverges or converges towards the axis of rotation. The diverging two-row bearings increase the rigidity of the shaft mounting while the converging double-row bearings do not.

The two-row bearings also have other configurations including two outer rings and a single inner ring as well as a single outer ring and two inner rings.

Four-row bearings consist of four rows of alternating diverging and converging rollers.

Materials Used In Tapered Roller Bearings

The most common materials used in the manufacture of tapered roller bearings are low-carbon steels and alloy steels. Some applications do require use of through-hardened or case-hardened, high-carbon, bearing-quality steel.

The high-carbon steel does not require carburizing and are either through-hardened via conventional heating methods or case-hardened via induction heating.

When low-carbon, carburized steel is used, the carbon is introduced once the roller bearings are machined to a depth sufficient to produce a hardened case with the ability to sustain bearing loads.

The inclusion of alloys and carbon ensured the proper combination of a ductile and tough core as well as a hard case resistant to fatigue.

Choosing Tapered Roller Bearings

When choosing tapered roller bearings, the outside diameter (OD) and bore size are important considerations.

The smallest dimension of the bearing is the bore size. The outside diameter includes the housing of the bearing but not the flange. Other important considerations include the static axial load, rated speed, static radial load, dynamic radial load, dynamic axial load, and overall width.

The static radial and static axial loads are, respectively, the maximum radial and axial loads that a bearing can withstand without deforming permanently.

The dynamic radial load and dynamic axial loads are, respectively, the calculated radial and axial loads under which a group of similar bearings that have stationary outer rings can withstand for a rating life of a million rotations of the inner ring.