A slewing bearing or slew [ing] ring (also called a turntable bearing) is a rotational rolling-element bearing that typically supports a heavy but slow-turning or slowly-oscillating loads in combination (axial, radial and moment loads), often a horizontal platform such as a conventional crane, a swing yarder, or the wind-facing platform of a horizontal-axis (yaw) windmill.

Slewing bearings are large-sized bearings specifically designed to accommodate oscillating movements. They are comprised of an inner ring and an outer ring, one of which usually incorporates a gear.

A slewing bearing, also known as a slewing ring, is a machine element that absorbs all axial and radial forces and the resulting tilting moments, in a single, self-retaining and ready-to-install bearing unit. The goal is to quickly and easily transfer the forces acting on the slewing bearing to the adjacent structural machine elements.

Slew bearings, also known as turntable bearings or slewing ring bearings, are large-diameter bearings, commonly used in heavy machinery, cranes, wind turbines and other applications requiring rotational support.