Sleeve bearings---"Communist Reports" folks don't much about bearings--The bearings in large generators are SLEEVE---they are lubed with pumpted oil under pressure---and they last---50,60 yrs???And keep in mind those bearings are supporting a rotor that is weighing hundreds of tons and turning at 1800,3600 RPM!They also seal the hydrogen coolant gas inside the generator.Don't worry-the generator won't explode with a pure atmosphere of the hydrogen gas inside it-cools better than air,and quenches arcs better.Back to the bearings-if sleeve bearings are lubed properly---they will OUTLAST sealed ball bearings.And if you have dried sleeve bearings-like on a Hoover Convertable--just dampen them with oil and---they WORK AGAIN-same with other sleeve bearing motors.