C3, C4 and C5 bearings are bearings that have an additional internal radial clearance to cope with high speed environments where excess heat is generated.
The radial internal clearance applies to bearings with an inner ring before the bearing is fitted. It is defined as CN, C2, C3, C4, C5 Internal clearance groups.
C2, Less than Normal. CN, Normal, only used in combination with letters indicating reduced or displaced clearance range. C3, Greater than Normal. C4, Greater
Internal clearance is the play within a ball bearing. It is the geometrical low torque. High loads. Heavy interference fits. High temperature. Preloaded. C3,C4,C5