After research, it was discovered that by slightly modifying deep groove ball bearings to reduce the contact surface between the ball and raceway, the requirements for fast rotation could be met. After decades of development, the angular contact ball bearing category was finally established.
Angular contact ball bearings are inseparable bearings. The contact surface between the ball and the inner and outer rings forms an angle, as shown in the figure above. Hence, they are called angular contact ball bearings. There are generally three contact angles: 15 degrees (code C), 30 degrees (code A or no code), and 40 degrees (code B).
Because angular contact ball bearings are biased to one side, they are generally used in pairs. There are three pairing configurations:
1. Back-to-back (code DB). As shown in the figure above, this is like two people leaning back to back. Because the distance L between the bearing points of application is larger, the bearing's torque load capacity is also greater.
2. Face-to-face (code DF). As shown in the figure above, this configuration resembles two people facing each other. The distance L between the points of action is small, resulting in a lower torque load capacity. However, the maximum tilt angle is greater than that of a back-to-back configuration. Since the two groups are aligned, the forces acting on them are offset. Therefore, both back-to-back and face-to-face configurations can support radial and bidirectional axial loads.
3. Tandem (code DT). As shown in the figure above, this configuration resembles two people facing each other. Since the bearings are aligned in the same direction, they can withstand greater unidirectional axial loads. Due to the presence of a protrusion, they can also withstand slight axial loads on the opposite side.
Four-point contact ball bearings are also a type of angular contact ball bearing. As shown in the figure above, they have a contact angle of 30 degrees and a separable inner ring. They can withstand bidirectional axial loads and are generally used in a two-point contact configuration under pure axial loads or combined loads with large axial loads.
Double-row angular contact ball bearings are generally assembled back-to-back. As shown in the figure above, they have a contact angle of 25 degrees. They are available in open, dust-shielded (code ZZ), non-contact sealed (code LLM), and contact sealed (code LLD).
