Do you know what is Four-point contact ball slewing bearings

According to the structure of the rolling elements, the slewing bearings are divided into two series: cross-roller slewing bearings and four-point contact ball slewing bearings. Reach P5/P4/P2 grades to meet the needs of various types of working conditions.

This article mainly explains the function characteristics, structural characteristics, and application fields of four-point contact ball slewing bearings.

Four-point contact ball slewing bearing features

Four-point contact ball slewing bearings can bear axial load, overturning moment, and radial load at the same time. Under the joint action of axial load and overturning moment, almost all the steel balls used participate in bearing the load. Under pure axial load, the steel ball and the inner and outer ring raceways are in single-point contact respectively. The models of contact ball bearings are FAG 7308-B-XL-TVP-UO, SKF 7220BEGAM, SKF 3320A, etc. When the radial load exceeds a certain value, there are two points of contact between the steel ball and the raceway of the inner and outer rings, and at this time, the wear and friction torque will increase. In order to cope with different combinations of axial force, overturning moment, and radial force generated under various working conditions, the contact angle can be adjusted accordingly, and the precision can reach P5/P4/P2 level.

Structure and Characteristics

The four-point contact ball slewing bearing is mainly composed of an inner ring, outer ring, a single row of steel balls, cage (or spacer block), sealing device, and other parts. The inner and outer rings of four-point contact ball slewing bearings have integral and split structures. The rigidity of the integral ferrule is relatively strong, and the split type is easy to adjust. The split structure has been connected with two split rings by bolts before the product leaves the factory.

Four-point contact ball slewing bearings usually have a cage (or spacer), and only when the load is large, the full-fill ball structure is used. The full-fill ball four-point contact ball bearing has a large load-bearing capacity, but the friction resistance is large and the friction is easy. Cause scratches on the surface of the steel ball. According to installation requirements, the mounting holes can be designed as straight holes, countersink holes, threaded blind holes, threaded through holes, etc.

The basic structure of four-point contact ball slewing bearings: no gear, external gear, internal gear.

Application

Four-point contact ball slewing bearings are suitable for occasions where the axial load is the main force, there is an overturning moment, and the frictional resistance is small. When installing, the support is required to have sufficient radial rigidity. Construction machinery such as rotary conveyors, welding manipulators, small and medium-sized cranes, and excavators can be selected.