Needle bearings are a bearing that is classified as either radial or thrust depending on the direction of the load being supported. Needle roller bearings include bearings whose rollers slightly exceed the size range of needle rollers as stipulated by ISO. Needle roller bearings include drawn cup and solid radial bearings, as well as application-specific cam followers, and roller followers. Thrust bearings include thrust needle bearings.
Equipped with a thin and long needle bearing roller (roller diameter, length 3 to 10 times the diameter of generally not more than 5mm), so the radial structure is compact, its diameter size and payload capacity compared with other types of bearings the same time, diameter minimum, especially for the radial bearing installation dimensions restricted results. According to the use of different occasions, may make use of, or needle roller bearings without inner ring and cage components, this time to match with the bearing journal surface and the surface of shell holes directly as bearing inner and outer rolling surface, in order to ensure the load capacity and operating performance and a ring bearing the same shaft or housing bore raceway surface hardness, machining accuracy and surface quality should be similar raceway of the bearing rings. Such bearings can only bear the radial load.