ISO Bearings

A word of caution, regarding IRC for those selecting ISO deep groove ball, cylindrical roller, and spherical roller bearings, is the “Normal” IRC shown in the tables for these bearings is not sufficient for these bearings if the bearing employs a “heavy” shaft fit. A heavy fit in most cases requires a “C3” IRC as a bearing with a “Normal” IRC could be too tight. A light to medium fit with a relatively high operating speed that generates heat also requires a “C3” IRC. If both a heavy fit is used along with a high speed, a “C4” IRC is typically required. Very few bearings with “Normal” IRC are used or stocked, with “C3” bearings being the most popular. For complicated applications, we recommend ISO Bearings that users of our bearings contact our sales department for specific fitting and clearance recommendations.

Standard Internal Radial Clearance values for deep groove ball, cylindrical roller, and spherical roller bearings are found in Tables XV through XXII. Please note that there are different standards for metric deep groove ball bearings and inch ball bearings, as well as ISO cylindrical roller bearings and domestic cylindrical roller bearings. Also, the IRC values KOYO 363 Bearing differ for straight bore bearings versus bearings with a tapered bore. There are no standards for tapered roller bearings. “Clearance” values for these bearings are expressed axially as “lateral” or “Bench End Play” (BEP) and are designed and specified for each application.