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