Bearings are an important component of contemporary machinery. Its main function is to support the mechanical rotating body, reduce the friction coefficient during its movement, and ensure its rotation accuracy.

According to the different friction properties of moving elements, bearings can be divided into two categories: rolling bearings and sliding bearings.

Commonly used in rolling bearings are deep groove ball bearings, cylindrical roller bearings and thrust ball bearings. Among them, rolling bearings have been standardized and serialized, and are generally composed of four parts: outer ring, inner ring, rolling body and cage.

Deep groove ball bearings mainly bear radial load, and can also bear radial load and axial load at the same time. When it is only subjected to radial load, the contact angle is zero. When the deep groove ball bearing has a large radial clearance, it has the performance of an angular contact bearing and can bear a large axial load. The friction coefficient of the deep groove ball bearing is very small and the limit speed is also high.

Deep groove ball bearings are the most representative rolling bearings and are widely used. It is suitable for high and even extremely high speed operation, and is very durable without frequent maintenance. This type of bearing has small friction coefficient, high limit speed, simple structure, low manufacturing cost and easy to achieve high manufacturing precision. The size range and form vary, and are used in precision instruments, low-noise motors, automobiles, motorcycles and general machinery and other industries, and are the most widely used type of bearings in the machinery industry. Mainly bear radial load, but also bear a certain amount of axial load.

Cylindrical roller bearings, the rolling elements are radial rolling bearings of cylindrical rollers. Cylindrical rollers and raceways are linear contact bearings. Load capacity, mainly bear radial load. The friction between the rolling element and the rib of the ring is small, which is suitable for high-speed rotation. According to whether the ring has ribs or not, it can be divided into single row bearings such as NU, NJ, NUP, N, NF, and double row bearings such as NNU and NN.

Cylindrical roller bearings without ribs on the inner or outer ring, the inner and outer rings can move relative to the axial direction, so they can be used as free end bearings. Cylindrical roller bearings with double ribs on one side of the inner ring and outer ring and a single rib on the other side of the ring can withstand a certain degree of axial load in one direction. Generally, a steel stamping cage is used, or a copper alloy turning solid cage is used. However, there are also part of the use of polyamide forming cage.

Thrust ball bearings are designed to withstand thrust loads during high-speed operation, and consist of washer-like ferrules with raceway grooves for ball rolling. Since the ferrule is in the form of a seat cushion, the thrust ball bearing is divided into two types: flat seat cushion type and self-aligning spherical seat cushion type. In addition, this bearing can withstand axial loads, but not radial loads.

Thrust ball bearings are composed of three parts: seat washer, shaft washer and steel ball cage assembly. The shaft washer matched with the shaft and the seat ring matched with the housing. Thrust ball bearings are only suitable for parts that bear axial load on one side and have low speed, such as crane hooks, vertical water pumps, vertical centrifuges, jacks, low-speed reducers, etc. The shaft washer, seat washer and rolling element of the bearing are separated and can be assembled and disassembled separately.