Four-point contact ball bearings are single row angular contact ball bearings, can withstand high axial loads in both directions, in the radial direction can only afford low load. In order to ensure low friction, especially at high speeds, requiring a guaranteed minimum axial load. Four-point contact ball bearings for the double semi-inner circle, so you can load as many balls. With steel balls and half of the outer ring inner ring component can be installed independently,-aligning bearing capacity is very small.