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(iv) Continue loading each shoe until a "hit" on a shoe provides the same movement on the
corresponding dial indicator for each shoe. The shoes should be equally loaded at this point.
corresponding dial indicator for each shoe. The shoes should be equally loaded at this point.
(v) Unless the shoes were very close to being equally loaded initially, the center of runout will have
moved significantly. Shim the bridge according to the procedure in section 7.1 to again plumb the
center of runout.
moved significantly. Shim the bridge according to the procedure in section 7.1 to again plumb the
center of runout.
(vi) Load all the shoes one more time, hitting each shoe equally while watching the dial indicators. As
the final shoe is hit, the center of runout should be back at its original position.
the final shoe is hit, the center of runout should be back at its original position.
(vii) Move the shaft so that the centerline of the thrust runner is directly over the center of the turbine
bearing housing. Because the center of runout is plumb, the center of runout will be 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.
bearing housing. Because the center of runout is plumb, the center of runout will be 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.
7.3 Procedure for Self Equalizing Thrust Bearing
a. Use a precision machinist level to level the upper bridge (lower bridge on an umbrella unit). Level
must be measured on a machined surface parallel to the surface of the bearing support.
must be measured on a machined surface parallel to the surface of the bearing support.
b. 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 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.
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 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.
c. Move shaft to center in turbine bearing housing and move the top of the shaft to make it plumb.
d. Hold shaft in place at upper guide and turbine guide bearings using jack bolts or bearing segments in
preparation for guide bearing installation. See section 8 for guide bearing installation procedures.
preparation for guide bearing installation. See section 8 for guide bearing installation procedures.
8. GUIDE BEARING INSTALLATION AND ADJUSTMENT
The final step in the alignment process is the installation and adjustment of the guide bearings. Once the
guide bearings are installed correctly, the alignment is finished and the reassembly of the unit can be
completed. At this point in the alignment process, the magnitude of static runout is acceptable and the
center of runout, or, in the case of the self-equalizing type thrust bearing, the shaft, should be plumb and
centered in the turbine bearing housing. The concentricity between the seal rings and the turbine bearing
should have been confirmed earlier. To complete the alignment, the generator guide bearings must be
installed concentric to the turbine guide bearing.
guide bearings are installed correctly, the alignment is finished and the reassembly of the unit can be
completed. At this point in the alignment process, the magnitude of static runout is acceptable and the
center of runout, or, in the case of the self-equalizing type thrust bearing, the shaft, should be plumb and
centered in the turbine bearing housing. The concentricity between the seal rings and the turbine bearing
should have been confirmed earlier. To complete the alignment, the generator guide bearings must be
installed concentric to the turbine guide bearing.
To make the generator guide bearings concentric to the turbine guide bearing, the shaft is used as a
reference. While not absolutely necessary, centering the shaft in the turbine bearing and making the shaft
plumb greatly simplifies installing the generator guide bearings if they are the adjustable shoe type. If the
shaft is plumb and centered in the turbine bearing, the shoes can all be set at their nominal radial
reference. While not absolutely necessary, centering the shaft in the turbine bearing and making the shaft
plumb greatly simplifies installing the generator guide bearings if they are the adjustable shoe type. If the
shaft is plumb and centered in the turbine bearing, the shoes can all be set at their nominal radial