Bearings are fixed parts in machinery. When other parts move relatively on the shaft, the parts used to keep the center position of the shaft and control the movement are called bearings.

In China's ancient books, the bearing structure has been recorded for a long time. 1279, Guo Shoujing, China, created a simple astronomical instrument, whose function is similar to that of modern thrust roller bearings. 1772, C. Wallow of Britain designed and manufactured ball bearings, and put them on a mail truck for trial use. 1794, P. Worth of Britain obtained the patent of ball bearing. /kloc-in the middle of the 0/9th century, with the progress of bearing materials, lubricants and mechanical manufacturing technology, Europe began to have relatively perfect sliding bearings. 188 1 year, H.R. Hertz of Germany published a paper on contact stress of ball bearings. On the basis of Hertz's achievements, R. Striebeck of Germany and A. Parmgren of Sweden carried out a lot of experiments, which contributed to the development of rolling bearing design theory and fatigue life calculation. 1883, N.P. Petrov of Russia applied Newton's viscosity law to calculate bearing friction. In the same year, when measuring the friction coefficient of vehicle bearings, British B. Thor found that there was oil film pressure in the bearings for nuclear submarines, and measured the oil film pressure distribution curve. 1886, O. Reynolds of Britain made a mathematical analysis of Thor's discovery, and derived Reynolds equation, which laid the foundation of hydrodynamic lubrication theory. Since 1960s, the theory of elastic hydrodynamic lubrication has gradually matured, and the service life of rolling bearings designed according to this theory has been greatly improved.