The balls rotate between the axis-ring and seat. The bearing can only withstand the direction of axial loading, can not afford radial loading. The axial load is evenly distributed in each ball, so the load capacity is greater, but when large temperature rises, it has a lower speed limit.
Thrust ball bearings can not restrict the axial movement or shell radial movement, but can restrict a direction of the axial movement, therefore, such bearings are usually associated with deep groove ball bearings.