The bearings representation in the

The bearings representation in the rotor system is of great importance. The hydropower
industry almost exclusively uses hydrodynamic journal bearings, with oil as a lubricant.
Most of the Swedish HPUs use journal bearings of the tilting pad type. However, some
older units still use plain journal bearings.
The shaft’s rotation and displacement give rise to a build-up of pressure between
the shaft and the bearing pads. The bearing pad tilts in to an equilibrium position due to
the pressure distribution on the pad. Figure 4 presents a schematic layout of a tilting pad
bearing. Static loads in the bearing cause static displacement, uS, of the shaft and the
dynamic loads cause dynamic shaft displacement, uD. The total displacement of the
shaft centre, in relation to the bearing centre, is uB=uS+uD. Figure 5 presents a
schematic visualisation of the static and dynamic displacements in the bearing.