Needle roller bearing is a roller bearing with cylindrical roller. Compared with its diameter, the roller is slender and long. This kind of roller is called needle roller. Despite its small cross-section, bearing still have high load-bearing capacity. Needle roller bearing are equipped with slender and long rollers (roller diameter D < 5mm, L/D < 2.5, L is roller length), so the radial structure is compact. When its inner diameter size and load capacity are the same as other types of bearing, the outer diameter is the smallest, which is especially suitable for supporting structures whose radial installation size is limited.
In order to ensure the same load capacity and operation performance as ring bearing, the surface hardness of raceway surface of shaft or shell hole should be similar to that of raceway of bearing ring. This kind of bearing can only bear radial load.