2
Rotor
Stator
Guide
Bearing
Figure 2.--Umbrella unit.
also be capable of supporting the weight of the unit when it is supported by the jacks. Figure 2
shows an umbrella unit, where the thrust bearing is located below the rotor. In the umbrella unit,
the rotating weight is transferred to the foundation through the lower bridge. The jacks are also
attached to the lower bridge. The upper bridge supports only the deck plates and the upper guide
bearing, if there is one. Both figures 1 and 2 are very general sketches of hydrounits, and while
most vertical units will resemble one of the figures, the specific construction and design details
vary between manufacturers. Understanding these design details, particularly the bearing
designs, is critical in developing a working alignment procedure. Listed below are descriptions
of some of the components most closely associated with the unit alignment.
shows an umbrella unit, where the thrust bearing is located below the rotor. In the umbrella unit,
the rotating weight is transferred to the foundation through the lower bridge. The jacks are also
attached to the lower bridge. The upper bridge supports only the deck plates and the upper guide
bearing, if there is one. Both figures 1 and 2 are very general sketches of hydrounits, and while
most vertical units will resemble one of the figures, the specific construction and design details
vary between manufacturers. Understanding these design details, particularly the bearing
designs, is critical in developing a working alignment procedure. Listed below are descriptions
of some of the components most closely associated with the unit alignment.
2.1 Thrust Bearings
Thrust bearings support the axial load on a rotating shaft. On a vertical shaft hydrounit, the
thrust bearing supports the entire rotating weight of the unit, as well as any hydraulic down thrust
from the turbine. There are typically three types of thrust bearings used in hydroelectric units:
the adjustable shoe, the spring loaded bearing, and the self equalizing. To the casual observer, all
thrust bearing supports the entire rotating weight of the unit, as well as any hydraulic down thrust
from the turbine. There are typically three types of thrust bearings used in hydroelectric units:
the adjustable shoe, the spring loaded bearing, and the self equalizing. To the casual observer, all