Four point bearings have on their outer and inner rings two circular arc-shaped raceways whose centres of curvature are offset so that during radial loading the balls contact the raceways at four points. The contact angles of four point bearings are large (usually 35�). Therefore these bearings are capable of transmitting high axial loads in both directions.
The form, radius and surface finish of the tracks is critical to the running performance and noise characteristics of these bearings. Taylor Hobson have a range of Form Talysurf systems which are suitable for measuring the form and surface finish characteristics of four point ball bearings.
Also of critical importance is the roundness and waviness of the races and rolling elements. Typically these features are measured using roundness instruments as detailed in the Talyrond links below.
Wall Thickness and Gothic Arch Analysis
Along with general geometrical features there is also typically a requirement to look at other critical factors which affect the running performance of these bearings. One of the important factors in ball bearing running performance is Wall Thickness Variation. While another critical factor is the relationship of the two arcs on the inner race to each other. Taylor Hobson have developed a dedicated analysis software for analysing both these features. For further details contact your local sales representative.