The Angular Contact Ball Bearing

Angular contact ball bearings, also known as spindle ball bearings, consist of an inner ring, outer ring, ball, and a cage to contain and separate the ball. Angular contact ball bearings can support an axial load, but cannot be used by a single bearing because of their angle. They must be used in combinations or in pairs.

An angular contact ball bearing uses axially asymmetric races. An axial load passes in a straight line through the bearing, whereas a radial load takes an oblique path that tends to want to separate the races axially. So the angle of contact on the inner race is the same as that on the outer race. Angular contact bearings better support “combined loads” (loading in both the radial and axial directions) and the contact angle of the bearing should be matched to the relative proportions of each. The larger the contact angle (typically in the range 10 to 45 degrees), the higher the axial load supported, but the lower the radial load. In high speed applications, such as turbines, jet engines, and dentistry equipment, the centrifugal forces generated by the balls changes the contact angle at the inner and outer race. Ceramics such as silicon nitride are now regularly used in such applications due to their low density (40% of steel). These materials significantly reduce centrifugal force and function well in high temperature environments. They also tend to wear in a similar way to bearing steel—rather than cracking or shattering like glass or porcelain.

Most bicycles use angular-contact bearings in the headsets because the forces on these bearings are in both the radial and axial direction.

Angular contact ball bearings have raceways in the inner and outer rings that are displaced with respect to each other in the direction of the bearing axis. This means that they are designed to accommodate combined loads, i.e. simultaneously acting radial and axial loads.

The axial load carrying capacity of angular contact ball bearings increases with increasing contact angle. The contact angle α is defined as the angle between the line joining the points of contact of the ball and the raceways in the radial plane, along which the load is transmitted from one raceway to another, and a line perpendicular to the bearing axis (fig).

SKF angular contact ball bearings are produced in a wide variety of designs and sizes. Those commonly used and included in this catalogue are
single row angular contact ball bearings
double row angular contact ball bearings
four-point contact ball bearings

Angular contact ball bearings are classified with different accuracy and tolerance ranges for ball bearings on the ABEC bearing rating scale. A higher ABEC number indicates that the bearing tolerances are tighter. When searching for your angular contact bearing, it is important to consider aspects like operation specifics and dimensions.

Operating Specifics for Angular Contact Ball Bearings

  • Static radial load: the maximum radial load the bearing can withstand without succumbing to the pressure
  • Dynamic radial load (calculated constant radial load): the amount of load a set of similar bearings with fixed outer rings can withstand against a rating life of one million revolutions of the inner ring
  • Rated speed: Grease lubrication gives a lower rated speed for bearings as compared to a bearing with oil lubrication.

Dimensions for Angular Contact Ball Bearings

  • Design units of angular contact bearings can be in either inches or metric units
  • Outside diameters include housing for housed units but exclude the flange for flanged bearings
  • Bore
  • Outer ring width

The most common types of angular ball bearing include four point contact ball bearings, singular row, and double row angular contact ball bearings. Angular contact bearings have different kinds and styles of shielding and seals, which essentially retain lubricant to provide protection against contamination. In this type of bearing, there are different types of seals and shields used, including single seal, double seal, single shield, and double shield. When compared to shields, seals provide better lubricant coverage and containment, but have a reduced maximum speed capability.

There are a variety of materials used in the construction of the angular contact bearing, including stainless steel, ceramic, and plastic. This type of ball bearing can also be plated. The materials that are commonly used to plate these bearings include chrome and cadmium.

Single row angular contact ball bearings and Tolerances

Angular contact ball bearings

Angular contact ball bearings have raceways in the inner and outer rings that are displaced with respect to each other in the direction of the bearing axis. This means that they are designed to accommodate combined loads, i.e. simultaneously acting radial and axial loads.

The axial load carrying capacity of angular contact ball bearings increases with increasing contact angle. The contact angle α is defined as the angle between the line joining the points of contact of the ball and the raceways in the radial plane, along which the load is transmitted from one raceway to another, and a line perpendicular to the bearing axis.

SKF angular contact ball bearings are produced in a wide variety of designs and sizes. Those commonly used and included in this catalogue are
– Single row angular contact ball bearings

Single row angular contact ball bearings can accommodate axial loads acting in one direction only. Under radial loads a force acting in the axial direction is produced in the bearing, and this force must be counteracted. Consequently the bearing is normally adjusted against a second bearing.

Normally SKF single row angular contact ball bearings have one high and one low shoulder. Some bearings, particularly those of Diameter Series 8 and 9, have an inner ring with two high shoulders as in a deep groove ball bearing. The low shoulder on one or both rings enables a large number of balls to be incorporated in the bearing, thus giving the bearings a relatively high load carrying capacity. They are of non-separable design.

The contact angle α is 40°, designation suffix B, for the most common sizes. For larger bearings contact angles of 25° and 30° are the most common, designation suffixes AC and A respectively.

SKF single row angular contact ball bearings are produced in two versions
– basic design bearings (not universally matchable) – can only be used for arrangements with single row ball bearing
– bearings for universal matching.

The larger sizes are produced exclusively as universally matchable bearings.

– double row angular contact ball bearings
– four-point contact ball bearings

Single row angular contact ball bearings

Single row angular contact ball bearings can accommodate axial loads acting in one direction only. Under radial loads a force acting in the axial direction is produced in the bearing, and this force must be counteracted. Consequently the bearing is normally adjusted against a second bearing.

Normally SKF single row angular contact ball bearings have one high and one low shoulder. Some bearings, particularly those of Diameter Series 8 and 9, have an inner ring with two high shoulders as in a deep groove ball bearing. The low shoulder on one or both rings enables a large number of balls to be incorporated in the bearing, thus giving the bearings a relatively high load carrying capacity. They are of non-separable design.

The contact angle α is 40°, designation suffix B, for the most common sizes. For larger bearings contact angles of 25° and 30° are the most common, designation suffixes AC and A respectively.

SKF single row angular contact ball bearings are produced in two versions
– basic design bearings (not universally matchable) – can only be used for arrangements with single row ball bearing
– bearings for universal matching.

The larger sizes are produced exclusively as universally matchable bearings.

Dimensions

The boundary dimensions of SKF single row angular contact ball bearings are in accordance with ISO 15:1998.

Tolerances

Basic design SKF single row angular contact ball bearings for single mounting are produced to Normal tolerances. Standard design universally matchable bearings are manufactured to better than Normal tolerances.

SKF Explorer angular contact ball bearings are manufactured only as bearings for universal matching with P6 dimensional accuracy and P5 running accuracy.

Large bearings having an outside diameter of approximately 400 mm and above have dimensional accuracy to tolerance class Normal and running accuracy to tolerance class P6 as standard.

The values for tolerances correspond to ISO 492:2002.

Resource From http://www.skf.com/portal/skf/home/products?lang=en&maincatalogue=1&newlink=1_3_6