What is the difference between needle roller bearings and cylindrical bearings

Needle roller bearings are equipped with thin and long rollers (roller diameter D≤5mm, L/D≥2.5, where L is the length of the roller), therefore their radial structure is compact. When the inner diameter size and load capacity are the same as those of other types of bearings, their outer diameter is smaller, so they are especially suitable for supporting structures where the radial installation size is limited. According to different application scenarios, bearings without inner rings or needle roller and cage assemblies can be selected. In this case, the journal surface and housing hole surface matched with the bearing directly serve as the inner and outer rolling surfaces of the bearing. To ensure that the load capacity and operation performance are the same as those of bearings with rings, the hardness, machining accuracy and surface quality of the raceway surface of the shaft or housing hole should be similar to those of the raceway of bearing rings. This type of bearing can only withstand radial loads.