Cage in ball bearing

Cage (bearing cage, also known as bearing retainer) refers to a bearing part that partially wraps all or part of the rolling body and moves with it to isolate the rolling body and usually guide the rolling body and keep it in the bearing. At present, cage is an essential part of rolling bearing design.

Initially, however, cages were not necessary. Bearings without retainers need to be filled with more balls, called full ball bearings. The increase in the number of balls allows these bearings to withstand heavier loads and respond more strongly to shocks, as loads can be distributed more evenly around the raceway. However, due to the design of ball-filling ports on the inner and outer rings, they are generally not suitable for high-speed applications or axial loads. With the advancement of steel technology, full ball bearings are also less common now.