the steam turbine-driven generators have auxiliary systems enabling them to work satisfactorily and safely. the steam turbine generator, being rotating equipment, generally has a heavy, large-diameter shaft. the shaft therefore requires not only supports but also has to be kept in position while running. to minimize the frictional resistance to the rotation, the shaft has a number of bearings. the bearing shells, in which the shaft rotates, are lined with a low-friction material like babbitt metal. oil lubrication is provided to further reduce the friction between shaft and bearing surface and to limit the heat generated.