There are methods that allow you to select motors in view of their actual duty cycle and temperatures reached during the duty cycle. Such methods are generally quite complex because it is necessary to determine the temperature rise of the engine, which is always a rather difficult and laborious task. In this way, the practical cases cover loads that vary in a known way many times, in a little precise way. The most practiced method in practice is to obtain a continuous regime parallel to the actual working regime of the engine.
These methods assume that the continuous equivalent regime (S1) will be thermally equivalent to the actual regime, without excessive heating or insulation damage. It should be noted that the equivalent continuous power rating should not be adopted as the average of the various powers that the load requires during a duty cycle. Such a procedure generally leads to the choice of an engine having a capacity below that required, since the losses associated with the various power ratings are not taken into account. For small load variations this procedure is however permissible. https://www.mrosupply.com/bearings/radial-ball-bearings/320047_6004-zjem_skf-bearing/