The double volleyball type turntable bearing has three races. The steel ball and isolation block can be directly discharged into the upper and lower raceways. Two rows of steel balls with different diameters are arranged according to the stress condition. This kind of open assembly is very convenient. The bearing angles of the upper and lower arc raceways are 90 ° and can bear large axial force and overturning moment. When the radial force is greater than 0.1 times of the axial force, the raceway must be specially designed. The axial and radial dimensions of double row spherical slewing bearing with different diameters are relatively large and the structure is tight. It is especially suitable for tower crane, truck crane and other loading and unloading machinery with medium or above diameter.

There are many forms of slewing bearing, but their structure composition is basically the same. Outer ring (toothed or toothless),. Sealing belt,. Rolling element (ball or roller), oil nozzle, plug, plug pin, inner ring (toothed or toothless), spacer or cage, mounting hole (threaded or smooth).

According to different structural types, turntable bearings can be divided into four point contact ball turntable bearings, cross cylindrical (tapered) roller turntable bearings, double row four point ball turntable bearings, double row reduced diameter spherical slewing bearings, ball roller combinations and three rows of cylindrical roller combined turntable bearings. The above bearings are divided into toothless ones according to whether they are toothed or not and the distribution of teeth There are different structures, such as type, external tooth type or internal tooth type.

According to the different structural characteristics of turntable bearing, it can meet the requirements of working host under different load conditions. Among them, four point contact ball slewing bearing has higher dynamic load capacity, cross cylindrical roller slewing bearing has higher static load capacity, three row cylindrical roller combined turntable bearing can lead the increase of bearing capacity to the bearing height direction, and various loads are borne by different raceways and roller groups, so the diameter of raceway is greatly reduced under the same stress condition, With the characteristics of making the main engine more compact, it is a high bearing capacity turntable bearing.

Slewing bearing is a kind of large bearing which can bear comprehensive load. It can bear large axial, radial load and overturning moment at the same time. Generally, slewing bearing is equipped with mounting hole, internal or external gear, lubricating oil hole and sealing device, which makes the design of main engine compact, easy to guide and easy to maintain. There are four series of slewing bearing: toothless, external and internal four point contact ball bearing, double row angular contact ball bearing, cross cylindrical roller bearing, cross tapered roller bearing and three row cylindrical roller composite bearing. Among them, four point contact ball bearing has higher static load capacity, cross cylindrical roller has higher dynamic load capacity, and cross tapered roller bearing has higher pre load capacity Interference can make the bearing have greater support rigidity and rotation accuracy. Due to the increase of bearing capacity, the three row cylindrical roller combined bearing leads to the bearing height, and various forces are borne by different raceways respectively. Therefore, the bearing diameter can be greatly reduced under the same stress, so the main engine is more compact. It is a slewing bearing with high bearing capacity. Slewing bearing is widely used in large-scale slewing device of hoisting machinery, mining machinery, construction machinery, port machinery, ship machinery, high-precision radar machinery and missile launcher. At the same time, we can also design, develop and produce all kinds of special structure slewing bearing according to the specific requirements of users.