2.2—Angular Contact Ball Bearings

Angular contact ball bearings can support radial loads and axial loads in one direction.
The line along the points where the balls contact the rings is inclined relative to the radial direction of the bearing. Due to this contact angle (α), an axial force is generated when a radial load is applied. Typically, double-row bearings or multiple bearing sets called arrangements are mounted to bear the axial component.

Generally, cages are made of pressed steel, but polyamide resin cages are sometimes used in high-precision bearings with contact angles of 30° or less.
Changing the arrangement configuration can provide different load-carrying characteristics.

Contact Angles

The contact angle of angular contact ball bearings allows them to sustain significant unidirectional axial loads and some radial load. The contact angle is indicated in the bearing designation with standardized codes.

2D cross-section of an angular contact ball bearing showing the imaginary line used to measure contact angle that is formed based on the load points where the ball contacts the outer and inner rings.

A diagram explaining the components of a basic designation for angular contact ball bearings. In the designation 7208B, the contact angle is indicated by the last code in the sequence (B).

Infographic about contact angle. The contact angle is determined by the contact points of the element in the bearing and is defined by ISO-designated codes (symbols) of C for 15°, A5 for 25°, A for 30°, and B for 40°. Higher contact angles have higher axial load capacity, but lower radial load capacity and limiting speeds and vice versa.

Cages for Angular Contact Ball Bearings

Pressed steel cage

3D model cross-section of a bearing with a resin cage.

Polyamide resin (Nylon-46) cage

Machined-brass cage

A heat treatment for dimensional stability can be applied to the rings and balls to allow the bearing to operate long-term at 120°C or higher.

Diagram of cage type suitability for operating temperatures. Nylon-46 cages can be used for long-term operation up to 150°C. L-PPS cages to 190°C, and machined brass cages across a wide range of temperatures.

Bearing Arrangements: Types and Characteristics

Bearing arrangements consist of two or more ball or roller bearings combined into a set with two or more rows.
Some features of two-bearing arrangements (paired mountings) of angular contact ball bearings are shown below.

Table comparing angular contact ball bearing arrangements and their features. All types are excellent for radial loads, DB types suit axial loads in both directions, while DF and DT types only support one direction, and DB and DF types both suit moment loads, though DB types are better due to a longer distance between effective load centers.

Arrangement Codes

Table comparing codes used for tapered bearing arrangements. All major companies NSK use the same naming scheme for two-row arrangements (DB, DF, and DT) but there are conflicting naming patterns for 3 and 4-row arrangements.

Note: Identical arrangement codes from different companies can have different meanings.

Double-Row Angular Contact Ball Bearings

Double-row angular contact ball bearings are essentially a back-to-back (DB) arrangement of two single-row angular contact ball bearings that share a single inner and outer ring.
These bearings can support radial loads, axial loads in both directions, and moment loads.

They are smaller in width than an arrangement of two bearings with the same outside diameter/bore dimensions.
Four types of single-row angular contact ball bearings are available with different contact angles (15°, 25°, 30°, and 40°), while double-row angular contact ball bearings (5xxx) have a contact angle of 25°.
Cages are typically made of pressed steel.
These bearings are commonly used in pumps, electric motors, and blowers.

3D model cross-sections of double-row angular contact ball bearings

Comparison of 5206 (double-row) and 7206ADB (arrangement)

		5206	7206ADB（M）
Bore Diameter (mm)		30	←
Outer Diameter (mm)		62	←
Width (mm)		23.8	32
Contact Angle (°)		25	30
Basic Load Ratings (kN)	Dynamic	29.6	36.5
Basic Load Ratings (kN)	Static	21.1	29.5
Limiting Speeds (min^-1)	Grease	7,100	10,000
Limiting Speeds (min^-1)	Oil	9,500	13,000

Comparison of Double-Row Angular Bearings (3xxx to 5xxx)

Designation		3xxx (compared to 5xxx)
Dimensions		Identical
Dynamic Load Rating		Low^＊1
Internal Design^*1	Outer Ring	Fill slot present（absent in 5xxx）^＊2
	Inner Ring	1 row（5xxx：2 row raceway groove）
	Balls	Numerous
	Ball Diameter	Small
	Contact Angle	Large

Notes

^*1 Some products from other companies have the same internal design for both 3xxx and 5xxx series bearings.
^*2 Some products from other companies do not have visible fill slots and use split inner ring.

Comparison of two types of double-row angular contact ball bearings with identical dimensions. Between bearing designations 5206 and 3206, only 3206 has a groove for inserting balls.

*In 3xxx, take care to ensure that the area where load is applied to the bearing (loaded zone) does not include the filling slot.

Four-Point Contact Ball Bearings

Four-point-contact ball bearings are single-row angular contact ball bearings with a separable inner ring.
These bearings can support radial loads and axial loads in both directions.
With a contact angle of 35°, they are well-suited for pure axial loads or combined loads where the axial portion is high.
A single four-point-contact bearing can replace a DF (front-to-front) or DB (back-to-back) arrangement.
Cages are typically made of machined brass.