It seemed as though nothing could stop the squealing. Not that the Monarch Cement Company’s huge ball mill wasn’t already loud. Powered by a 5,000-horsepower motor, it pulverizes 100 tons of clinker (a burned mixture of limestone and shale) per hour. But the squealing was not what Randy Riebel wanted to hear. As electrical supervisor at Monarch’s plant in Humboldt, Kan., he knew the noise meant the motor’s bearings were going – again.