According to the use mode and gear structure of the slewing bearing (slewing ring), the slewing bearing is divided into three types: memory type, external gear type, and gearless type. Each type of slewing bearing has these three types. Double-row ringball bearings are divided into double-row ball inner-tooth slewing bearings, double-row ball outer-tooth slewing bearings, double-row ball non-tooth slewing bearings; four-point contact ball slewing bearings are also divided into four Point contact ball internal gear slewing bearing, four point contact ball external gear slewing bearing and four point contact ball non-tooth slewing bearing.
The double-row ringball bearings, with two rows of steel balls, can bear radial force, axial force and overturning moment at the same time. Double-row ringball bearings are widely used in large rotating devices such as bucket wheel machines, overweight transport machinery, port machinery, mining machinery, construction engineering machinery, park amusement machines, filling machines and missile launchers.
The four-point contact ringball bearing is a separable bearing. It can also be said to be a set of angular contact ringball bearings that can bear bidirectional axial load. The inner and outer ring raceways are peach-shaped cross-sections. When there is only pure radial loading, the steel ball and the ferrule appear to be in four-point contact, which is the origin of this name; when only a pure axial load acts, the steel ball and the ferrule become two-point contact, which can withstand two-way axial load . Four-point contact ball bearings can also bear moment loads and have the functions of single row ball slewing bearings and double-row angular contact ball bearings. Four-point contact ball bearings can only ensure normal operation when they form two-point contact. Therefore, it is generally suitable for those occasions where there is two-point contact under pure axial load or synthetic load with large axial load. The four-point contact ball bearing has a high limit speed and is also suitable for those high-speed running occasions.