Characteristic of structure,performance and application The single-row four points contact ball Slewing Bearing is composed of 2 seat-rings.It features compact in design,and light in weight.The balls contact with the circular race at four points,via which the axial force,radial force and resultant moment may be born simultaneously. It may be used for slewing converter,welding arms and positioning,light,medium duty cranes,excavators and other engineering machines.