Four-point contact ball slewing bearings are radial single row angular contact ball bearings with raceways that are designed to support axial loads in both directions. For a given axial load, a limited radial load can also be supported (→ Load ratio). The bearings are separable, i.e. the outer ring with ball and cage assembly can be mounted separately from the two inner ring halves.
Both inner ring halves four-point contact ball bearings have a recessed shoulder. This improves oil flow when the bearing is used in combination with an SKF cylindrical roller bearing. In addition, these recesses can be used to facilitate dismounting.
4-point slewing bearings do triple duty while saving space
A four-point contact ball bearing makes it easy to simplify machine designs that have a combination of radial, thrust and moment loads because it can handle all three simultaneously. They are primarily used for slow to moderate-speed applications, or where oscillatory movement is predominant.
Four-point contact bearings are especially effective in applications in which the rotating element has a high ratio of diameter to axial length. Most have a large ratio of bore to section size: the larger this ratio, the thinner and more flexible are the individual races. Thin section bearing sizes range from 1" to 40" and slewing ring bearings range from 4" to 178" O.D.
Four-point contact ball bearings are typically manufactured of conventional antifriction bearing materials but, like other bearings, materials decisions are ultimately dictated by the application. High-carbon 52100 alloy and 440C stainless steel are common choices for through hardening. When selective hardening is needed