Tapered Roller Bearings

Tapered roller bearings consist of an inner ring (cone), an outer ring (cup), a cage and rollers which are profiled to distribute the load evenly. They have high radial and axial (thrust) load capacities at low to intermediate speeds. Tapered roller bearings are available in single-row, two-row and four-row designs. With single-row bearings, the thrust load capacity is about 60% of the radial capacity. Double-row bearings have a greater radial load capacity and can handle thrust loads in both directions. The rollers can be configured in such a way that the contact lines between the roller and the race converge or diverge towards the axis of rotation. Diverging double-row bearings increase the rigidity of the shaft mounting, while converging bearings do not. Other configurations for double-row bearings feature a single outer ring and two inner rings, or two outer rings and a single inner ring. Four-row tapered roller bearings consist of four rows of alternating converging and diverging rollers.

Most tapered roller bearings are made of alloy steels or low-carbon steels. Some applications require the use of case-hardened or through-hardened, high-carbon, bearing-quality steel. High-carbon grades of steel do not require carburizing and can be case-hardened by induction heating or through-hardened by conventional heating methods. When low-carbon, carburized grades of steel are used, carbon is introduced after the cylindrical roller bearings are machined to a depth sufficient to produce a hardened case that can sustain bearing loads. The addition of carbon and alloys ensures the proper combination of a hard, fatigue-resistant case and a tough, ductile core.

Bore size and outside diameter (OD) are important specifications to consider when selecting tapered roller bearings. The bore size is the bearing's smallest dimension. The outer diameter includes the bearing housing, but excludes the flange. Other important specifications for taper roller bearings include overall width, rated speed (oil), static axial load, static radial load, dynamic axial load and dynamic radial load. Static axial and static radial loads are, respectively, the maximum axial and radial loads that a bearing can withstand without permanent deformation. Dynamic axial load and dynamic radial loads are, respectively, the calculated axial and radial loads under which a group of identical bearings with stationary outer rings can endure for a rating life of 1 million revolutions of the inner ring.

Single-row tapered roller bearings

The single-row tapered roller bearings are able to carry radial and axial load in one direction simultaneously. Because an axial component of force is produced when this type of bearing is loaded radially, two or more bearings are matched and used together.

There are the standard, medium and steep types which differ in contact angle size. Medium-tapered metric series bearings are identified by the supplementary code "C" which is added as a suffix to bearing numbers.

Bearings whose cup width, cup smaller inside diameter and contact angle are determined in accordance with ISO 355 specifications are identified by the supplementary code "J" as a suffix. Cone assemblies and the cups of such bearings are inter-changeable with those of bearings produced abroad if the bearing numbers are the same.

Double-row tapered roller bearings

These bearings are divided into the TDO type which has one double cup and two single-row cones, and the TDI type which has two single-row cups and one double cone.

Both accommodate radial and axial loading in both directions. These two also carry moment loads; however, the TDO type is superior to the TDI type, because the distance between load centers is longer in the TDO type. The spacer of the TDO type, or the TDI type, pre-adjusts the internal clearance to provide proper operating clearance after mounting.

Features and benefits:

  • Forged steel vs. seamless tubing
  • Improved fatigue life
  • Reduced noise vibration
  • Super finished raceways
  • Crowned inner ring, raceway & rollers