Needle bearing, a roller bearing with cylindrical roller, is thin and long compare with its diameter. This roller is called needle roller. Despite the small cross-section, the bearing still has a high load bearing capacity. It is equipped with thin and long rollers (roller diameter D≤5mm, L / D≥2.5, L is the roller length), so the radial structure is compact. When the inner diameter size and load capacity are the same as other types of bearings, the outer diameter is the smallest. It is especially suitable for the support structure with limited radial installation size.

According to the different occasions, the bearing or needle roller and cage assembly without inner ring can be selected. At this time, the surface of the journal matching the bearing and the surface of the housing hole are directly used as the inner and outer rolling surfaces of the bearing. Same as the bearing with ring, the hardness, machining accuracy and surface quality of the surface of the shaft or shell hole raceway should be similar to the raceway of the bearing ring. Such bearings can only bear radial loads.