A thrust bearings is a particular type of rotary bearings, which consist of two precision chrome steel washers and a ball complement space by bronze retainer.
Like other bearings they permit rotation between parts, but they are designed to support a high axial load.
Thrust bearings come in several varieties, one of which use steel ball as the parts. 
That is ball thrust bearings. 
It compose of ball bearings supported in a ring, can be used in low thrust applications where there is little radial load. 
There are still contain other types of thrust bearings, such as roller thrust bearings, tapered roller bearings, fluid bearings etc. 
They are commonly used in automotive, marine, and aerospace applications.