A bearing shell is the part of a sliding bearing that contacts the journal. It is a semi-cylindrical surface shaped like a tile, very smooth, and generally made of wear-resistant materials such as bronze or anti-friction alloys. In special cases, it can be made of wood, engineering plastics, or rubber.
Bearing shells come in two types: integral and split. Integral bearing shells are usually called bushings. Integral bearing shells are available with or without oil grooves. The bearing shell and journal use a clearance fit and generally do not rotate with the shaft.
When a sliding bearing is working, a thin oil film is required between the bearing shell and the shaft for lubrication. If lubrication is poor, direct friction occurs between the bearing shell and the shaft. This friction generates very high temperatures. Although the bearing shell is made of special high-temperature resistant alloy materials, the high temperatures generated by direct friction are still enough to burn it out. Bearing shells can also burn out due to excessive load, excessive temperature, impurities in the lubricating oil, or abnormal viscosity. Burning out the bearing shell results in the failure of the sliding bearing.