Self Aligning Ball Bearings
Double row self-aligning ball bearings are designed with two rows of balls and round raceway on the outer ring, which enables certain tilting of the inner ring towards the outer ring around the bearing centre without impeding bearing function.
Bearings are made with a cylindrical or tapered bore (indicated by a K in the part title with a taper of 1:12) and are non-detachable. The self aligning ability, while maintaining functionality, determines the bearing application in cases, where certain misalignment of bores in the bearing hubs or deflection and oscillation of the shaft are expected. Due to the small contact angle and imperfect adherence of the balls to the raceways, they are unsuitable for capturing greater axial forces.
C3 indicates that the bearing has a greater-than-normal internal radial clearance between the rolling elements (balls or rollers) and the raceways. This extra space allows the bearing to handle thermal expansion caused by high speeds or high temperatures, preventing seizing.