What are the meanings of FW, EW and BC in needle roller bearings

FW: the diameter of the inscribed circle of the non inner ring bearing composed of rollers. The diameter FW of its inscribed circle is used to replace the radial internal clearance. The matching shaft is the tolerance zone of H6

EW: diameter of circumscribed circle of non outer ring bearing composed of rollers.

BC: BC dimension is a negative tolerance dimension (cage width of needle roller and cage assembly), and the width of raceway surface must be consistent with BC.


FW and EW are also used for short cylindrical roller bearings. The above explanation is partly from ina.