Needle roller bearing 

Needle roller bearing /cam follower is composed of a stud used as the tray of a group of rollers and a thick wall outer ring .The shoulder of the stud and the surface retaining ring on the stud form the guiding faces on the two sides of the outer ring.When the curve rollers are running on the plain tray or cam wheel,the inner stress on the rollers will increase due to the deformation of the outer ring.Therefore the rated load should be selected as curve roller column in this operational case. 

Needle Roller bearings