The single-row crossed roller slewing ring is composed of two seat-rings. It features compact in design, light in weight, high precision and small fitting clearance. As the rollers are 1:1cross arranged, it is suitable for high precision mounting and capable to bear axial force, resultant moment and considerable large radial force. The single-row crossed roller slewing rings are widely used for hoisting, transporting, engineering machines as well as for military products. Its designs are available by three types: inner gear, outer gear, and without gear.