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 ≤ 5 mm, 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.
Depending on the application, bearings or needle roller and cage assemblies without inner ring can be used. The journal surface and the housing hole surface that match the bearing directly serve as the inner and outer rolling surfaces of the bearing to ensure load capacity and running performance. As with ferrule bearings, the hardness of the raceway surface of the shaft or housing bore, the machining accuracy and surface quality should be similar to the raceway of the bearing ring. This type of bearing can only withstand radial loads.