A thrust bearing is a particular type of rotary rolling-element bearing. Like other bearings they permit rotation between parts, but they are designed to support a predominately axial load.
Thrust ball bearings, composed of ball bearings supported in a ring, can be used in low thrust applications where there is little axial load.
According to the stress concentration points, thrust ball bearings can be divided into single direction thrust ball bearings and double direction thrust ball bearings. 
Thrust bearings are commonly used in automotive, marine, and aerospace applications. They are also used in the main and tail rotor blade grips of RC (radio controlled) helicopters.