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