Basic Concept Of Needle Roller

Needle roller bearings are equipped with thin and long rollers (the roller length is 3 to 10 times the diameter, and the diameter is generally not more than 5mm), so the radial structure is compact.When its inner diameter size and load capacity are the same as other types of bearings, the outer diameter is the smallest, which is particularly suitable for bearings with limited radial installation dimensions. Depending on the application, bearings without inner rings or needle roller and cage assemblies can be selected. At this time, the journal surface and shell hole surface matching the bearing are directly used as the inner and outer rolling surfaces of the bearing. In order to ensure that the load capacity and operating performance are the same as those of bearings with rings, the hardness, processing accuracy and surface quality of the shaft or shell hole raceway surface should be similar to those of the bearing ring raceway. This type of bearing can only bear radial loads.
Model comparison
1. Radial needle roller and cage assembly (K type);
2. Needle roller bearing with double locking ring on the outer ring (NA type, NKI type, RNA type, NK type);
3. Single row needle roller bearing with double ribs on the outer ring (NA type, NKI type, RNA type, NK type);
4. Double row needle roller bearing with double ribs on the outer ring (NA type, RNA type);
5. Stamped outer ring needle roller bearing (HK type, BK type).
This type of bearing has low cost and large load capacity. It is suitable for supporting structures with limited installation dimensions. The surface of the journal is hardened as the rolling surface. The bearing is pressed into the seat hole and no axial positioning is required. The bearing should be injected with an appropriate amount of grease before installation. Under normal circumstances, it does not need to be lubricated after assembly. BK type bearings are used in supports without extended ends of the journal. The end face is sealed to act as a seal and can withstand small axial play.