In order to ensure the smooth and reliable operation of the bearing, most bearings are lubricated with lubricating oil, to reduce the internal friction and wear of the bearing and prevent burning and sticking, to prolong the fatigue life of the bearing, to drain the friction heat and heat from the outside. At the same time, the oil film also has a certain vibration absorption capacity. However, one of the biggest disadvantages of adding lubricating oil is that it needs good sealing performance, otherwise there will be leakage, and some equipment with special requirements do not allow lubricating oil leakage, so people use other lubricating materials to replace lubricating oil, and invent oil-free bearing, so that it not only has the advantages of lubricating oil bearing, but also eliminates environmental pollution caused by leakage. Oil-free bearings mainly include gas-lubricated bearings, composite lubricated bearings, water-lubricated bearings and so on.

Gas lubricated bearing is a sliding bearing with gas as lubricant. The most commonly used gas lubricant is air, which can also be used as nitrogen, argon, hydrogen, Helium and so on. The mechanism of gas lubricated bearing forming bearing gas film is the same as that of liquid lubricated bearing. Gas lubricated bearings make use of gas transmission diffusivity, viscosity and heat conductivity, adsorption and compressibility, to form a layer of complete gas film, which has the function of supporting load and reducing friction.

Due to the requirements of special production technology, some key equipment of industrial and mining enterprises operate under very bad working conditions. Due to heavy equipment, high ambient temperature, large dust or acid corrosion gas in the air, lubrication of equipment become problems, friction and wear are serious. Many equipment are still used traditional oil, grease lubrication, in fact, these industrial and mining conditions have exceeded the scope of oil and grease lubrication. It is easy to bite or bite bearings and other friction pairs, to causing serious wear and damage of parts.

Since the oil resources crisis appeared in the 1970s and people pay attention to environmental protection in recent years, the oil pressure transmission technology is facing severe challenges, and the water lubricated bearings began to be popularized and applied step by step. Water lubricated bearings with water as lubrication and working medium can not only save a lot of oil, but also avoid the pollution of traditional bearings with oil as lubrication medium. At the same time, water is an ideal lubricating medium because of its advantages of no pollution, wide source, safety and flammability. It can also reduce the friction, wear, vibration, noise, reactive power consumption and other key problems. Therefore, the research of water-lubricated bearings is of great importance to the improvement of water-lubricated bearings. Mechanical efficiency and environmental protection have important theoretical research and application value, and have become a hot spot in various countries.