Needle bearing is a roller bearing with cylindrical roller, which is thin and long relative to its diameter. This roller is called a needle roller. Although it has a small cross-section, bearing still has high load capacity. Needle bearing has fine and long roller (roller diameter D 5 mm or less, acuity 2.5 L/D, L) for the roller length, so the radial structure is compact. When its diameter and load capacity are same as those of other types of bearing, the outside diameter is smallest, which is especially suitable for the limited size of the radial installation supporting results. According to the use of different occasions, it can be used without inner ring of the bearing or needle roller and cage components. At this time, the surface of the journal and the surface of the casing which are matched with the bearing are directly used as inner and outer rolling bearing surface. In order to ensure the load capacity and operation performance and have the same ring bearing, axis or shell hole hardness on the surface of the raceway, machining accuracy and surface quality should be similar to the raceway of the bearing ring. This bearing can only bear radial load. The needle roller bearing of stamping outer ring is a needle roller bearing with thin forming outer ring.
Matters needing attention
Needle roller bearing has large bearing capacity and is suitable for supporting structure with limited mounting size.
The surface of the journal is hardened to serve as the rolling surface, and the bearing is loaded into the bore by pressing in, so that it does not need to be positioned axially.
Bearings should be injected with an appropriate amount of grease before installation. Generally, BK type bearings are not required to be lubricated after assembly for bearing no protruding end of the journal.