Needle roller bearings can be divided into the following categories according to their structure:
(1) Enclosed stamped outer ring needle roller bearings
(2) needle roller bearings with inner rings
(3) and needle roller bearings without inner ring/needle roller bearings without inner ring and cage
(4) Needle roller bearings with and without retainers
(5) Needle roller bearings without fenders
(6) Self-aligning needle roller bearings
(7) Combined needle roller/ball bearing
(8) Combined needle roller/thrust ball bearing
(9) Combined needle roller/cylindrical roller thrust bearing.