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e. Move the shaft so that the centerline of the thrust runner is directly over the center of the turbine
bearing housing. Since the center of runout is plumb, this will also make the center of runout
concentric with the turbine bearing housing. Lock the thrust runner in place with jacking bolts or
bearing segments in preparation for guide bearing installation. See section 8 for guide bearing
installation procedures.
concentric with the turbine bearing housing. Lock the thrust runner in place with jacking bolts or
bearing segments in preparation for guide bearing installation. See section 8 for guide bearing
installation procedures.
7.2 Procedures for Adjustable Shoe Thrust Bearing
There are two basic procedures listed below for aligning units with adjustable shoe thrust bearings. The
first method requires making all shaft plumb and bearing loading adjustments by adjusting the thrust
bearings. The bearings are loaded and made level by adjusting bearing height. The second method uses
the adjustable feature of the shoes only to achieve equal loading. The bearings are leveled, and therefore
the center of runout made plumb, by shimming the bridge similar to the procedure for spring loaded
bearings.
first method requires making all shaft plumb and bearing loading adjustments by adjusting the thrust
bearings. The bearings are loaded and made level by adjusting bearing height. The second method uses
the adjustable feature of the shoes only to achieve equal loading. The bearings are leveled, and therefore
the center of runout made plumb, by shimming the bridge similar to the procedure for spring loaded
bearings.
Some adjustable shoe thrust bearings are equipped with strain gages to measure the loading on the
individual shoes. Before using the strain gages, they should be thoroughly checked to make sure they are
properly bonded and functioning properly. After 20 or more years submersed in oil, there are usually one
or more gages that are not working properly. In most cases, if strain gage measurement is desired, it is a
good idea to install all new gages.
individual shoes. Before using the strain gages, they should be thoroughly checked to make sure they are
properly bonded and functioning properly. After 20 or more years submersed in oil, there are usually one
or more gages that are not working properly. In most cases, if strain gage measurement is desired, it is a
good idea to install all new gages.
Adjustable Shoe Thrust Bearing - General
a. Take plumb readings with the shaft in the zero degree position and plot the shaft profile. If the dogleg
is excessive, make corrections as discussed in section 6.2. Take clearance readings of the turbine seal
rings, turbine bearing housing, generator stator, and generator guide bearing housings if the guide
bearing housings are not adjustable. Plot the centerlines of the static components on the shaft plumb
plots to determine concentricity. The concentricity should be checked even if the stationary
components were centered with a single plumb wire with the rotating components removed.
rings, turbine bearing housing, generator stator, and generator guide bearing housings if the guide
bearing housings are not adjustable. Plot the centerlines of the static components on the shaft plumb
plots to determine concentricity. The concentricity should be checked even if the stationary
components were centered with a single plumb wire with the rotating components removed.
b. Take static runout readings using either Method I or II. If the magnitude of static runout exceeds the
tolerance in table 1, make necessary corrections as discussed in section 6.6. Plot the runout readings
and, using the plot of the plumb readings, determine the position of the center of runout relative to the
shaft at the thrust bearing elevation.
and, using the plot of the plumb readings, determine the position of the center of runout relative to the
shaft at the thrust bearing elevation.
Adjustable Shoe Thrust Bearing - Method I
(i) If the plumb of the center of runout is out of tolerance, corrections will be made by adjusting the
thrust shoes. Check location of adjustment screw and that there is clearance for the slugging wrench
and hammer at all bearings. If the center of runout is significantly out of plumb, it may be desirable to
shim the bridge to try to bring the center of runout closer to plumb. This will limit the amount of
movement required of the thrust shoes. Follow the shimming procedure under section 7.1.
thrust shoes. Check location of adjustment screw and that there is clearance for the slugging wrench
and hammer at all bearings. If the center of runout is significantly out of plumb, it may be desirable to
shim the bridge to try to bring the center of runout closer to plumb. This will limit the amount of
movement required of the thrust shoes. Follow the shimming procedure under section 7.1.