Double row contact ball slewing bearing has three rings, balls and spacer blocks can be arranged in the upper and lower rings directly, Install two rows different diameters balls according to the stress conditions.This kind of open assembly is very convenient, for the upper and lower raceway arc Angle of 90°, can bear large axial force and tilting moment.When the radial force is greater than 0.1 times of the axial force, special raceway design is required.This types slewing bearings have large axial and radial dimensions and strong structure, so it is especially suitable for middle diameter tower crane, truck loading crane and other loading and unloading machinery.