Non-Standard Model Slewing Bearing is also called slewing ring, slewing ring bearing, turntable bearing, and rotary bearing.
The single row ball slewing ring bearing is composed of 2 seat-rings. The balls contact with the circular race at four points, via which the axial force, radial force and resultant moment may be born simultaneously.

A slewing bearing or slew[ing] ring is a rotational rolling-element bearing that typically supports a heavy but slow-turning or slow-oscillating load, often a horizontal platform such as a conventional crane, a swing yarder, or the wind-facing platform of a horizontal-axis windmill.