The slewing bearing has an important position in industrial production. The main reason why it is widely used is because its use can quickly solve many problems in the construction machinery industry. Because the reverse support has four-point contact ball bearings, double-row angular contact ball bearings, crossed cylindrical roller bearings, crossed tapered roller bearings and three-row cylindrical roller combination bearings without gears, external gears and internal gears and other structural types, among which the four-point touch ball reversing bearing has a higher static load capacity; the crossed cylindrical roller bearing has a higher dynamic load capacity; the crossed tapered roller bearing can make the bearing have a higher capacity after pre-interference. Large support rigidity and high reversal accuracy, so the use of slewing bearings in construction machinery has been widely promoted.