Some Mechanical Considerations in the Design of Large Thrust Bearings

Abstract

The modern thrust bearing is a very important part of the waterwheel generator, for it must support the weight of the rotating parts of the turbine and generator and the hydraulic thrust load. With the continuous increase in size of hydroelectric generating units, machines now are built with thrust loads well above 1000 tons and requiring bearings ten feet in diameter or larger. Continuous trouble-free operation for periods of twenty years or more are desired for the bearings of large hydroelectric units. Except during the starting period, the pivoted pad thrust bearing operates according to the well-known hydrodynamic theory of lubrication which permits the predetermination of its performance with reasonable accuracy. Alternating slipping between the thrust bearing runner and the supporting structure can result in excessive wear which destroy the accuracy of the bearing surfaces. Such wear can cause undesirable vibrations or damage to the bearing surface which prevents the formation of an adequate oil fi...