Purpose of Standard Roller bearing performance is a function of many variables. These include the bearing design@ the characteristics of the material from which the bearings are made@ the way in which they are manufactured@ as well as many variables associated with their application. The only sure way to establish the satisfactory operation of a bearing selected for a specific application is by actual performance in the application. As this is often impractical@ another basis is required to estimate the suitability of a particular bearing for a given application. This is the purpose of this standard. This standard specifies the method of calculating the basic dynamic load rating of rolling bearings within the size ranges shown in the relevant ANSI/ABMA standards@ manufactured from contemporary@ commonly used@ good quality hardened steel in accordance with good manufacturing practice and basically of conventional design as regards the shape of rolling contact surfaces. This standard also specifies the method of calculating the basic rating life@ which is the life associated with 90% reliability@ with commonly used material and manufacturing quality@ and with conventional operating conditions. In addition@ it specifies the method of calculating adjusted rating life@ in which various reliabilities@ special bearing properties and specific operating conditions are taken into account by means of life adjustment factors. Furthermore@ this standard specifies the method of calculating the basic static load rating and the static equivalent load for roller bearings within the size ranges shown in the relevant ANSI/ABMA Standards@ manufactured from good quality hardened steel@ in accordance with good manufacturing practice and basically of conventional design as regards the shape of rolling contact surfaces.