Used to determine the rotational axis and the other parts moving relative position, it’s supporting or guiding role of parts. The bearing is in the process of mechanical drive in fixed and reducing load on friction coefficient of components. Also can say, when the other parts on the shaft with each other to generate relative movement, used to reduce the power transmission in the process of friction coefficient and to keep the shaft center position fixing machine. The bearing plays a decisive role in modern machinery and equipment spare parts. Its main function is to support the rotary body, so as to reduce the equipment in the transmission process of the mechanical load friction coefficient. According to the movement of friction properties of the different components, bearings can be divided into two types of rolling and sliding bearing.
China is the one of the countries in world that earlier invention of rolling bearing, the Chinese ancient books, on the axle bearing structure has long been documented. From archaeological artifacts and information, China oldest modern rolling bearing structure prototype of bearing, appeared in221 BC to 207 years (Qin) of this Shanxi province Yongji County Xue cliff village. After the founding of new China, especially since the seventies of last century, in the reform and opening up the powerful impetus, bearing industry has entered a new period of rapid development of high quality. Since the founding, Chinese bearing industry has gained the success.
Study in terms of its role should be to support, that is used for bearing the literal interpretation, but this is only a part of its roles, supporting its essence is able to bear the radial load. Also it can be understood as it is used to a fixed axis. It is a fixed axis so that it can only be achieved by turning, and the control of its axial and radial movement. Motor without bearing the consequences isn’t work. Because the shaft may move in any direction, and electrical work required only for rotating shaft. Theoretically impossible transmission effect, not only such, bearing will affect the transmission, in order to reduce the impact of the high speed shaft bearing must achieve good lubrication, some bearing itself has lubrication, called pre lubricating bearings, and most of the bearing must have oil, load at high speed operation, due to friction not only will increase energy consumption, more terrible is easily damaged bearing. The sliding friction into rolling friction is one-sided, because there is something called sliding bearing.
(1) Miniature bearings -- Nominal outside diameter size range below 26mm bearing
(2) Small bearings -- Nominal outside diameter size range is 28-55mm bearing;
(3) Small and medium-sized bearings -- Nominal outside diameter size range is 60-115mm bearing;
(4) In large bearing -- Nominal outside diameter size range is 120-190mm bearing
(5) The large bearing -- Nominal outside diameter size range is 200-430mm bearing;
(6) Large bearings -- Nominal outside diameter size range for the 440-2000mm bearing.
(7) Major type bearings -- Nominal outside diameter size range is more than 2000mm bearing.
According to the aperture of distinguish, such as pore size below 10mm for miniature bearings.