NSK self-aligning ball bearings are produced as standard with Normal radial internal clearance and most are also available with the greater C3 clearance. Many bearings can also be supplied with the smaller C2 clearance or the much greater C4 clearance.
Bearings in the 130 and 139 series have C3 radial internal clearance as standard.
Bearings with an extended inner ring have a radial internal clearance which lies in the C2 + Normal range.
Clearance values are provided in the table and are in accordance with ISO 5753:1991. They are valid for unmounted bearings under zero measuring loads.