Follow these procedures when checking endplay in a ball bearing machine
"We rebuilt a 75 hp electric motor recently. It ran fine in the service center, but the customer reported high bearing temperatures shortly after installing the motor. The bearings failed after only a few hours at full load." The first response for most of us is to suspect an alignment problem. But there is another possibility that should be considered. An electric motor must have room for thermal expansion of the shaft, or bearing life will be severely reduced. The endplay of a ball bearing motor plays an important role in bearing life.