Four-point contact bearings are single-row angular contact ball bearings and therefore require significantly less space in an axial direction than double-row designs.
The bearings comprise solid outer rings, split inner rings and ball and cage assemblies with brass or polyamide cages. The two-piece inner rings enable a large complement of balls to be accommodated. The inner ring halves are matched to the particular bearing and must not be interchanged with those of other bearings of the same size. The outer ring with the ball and cage assembly can be mounted separately from the two inner ring halves.
The single row four-point contact 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 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.