Angular contact ball bearings are non-separable type bearings and typically used for carrying combined (axial and radial) loads. They can carry pure axial load and operate in higher speed. That's why many people refer to them incorrectly as thrust bearings. There are three basic types of angular contact ball bearings: 

Single Row Bearings 
Double Row Bearing 
Four Point Contact Ball Bearings 
Single row 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 a 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.