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(ii) Use the data is step (b) to make a new plot with points for the relative position of the center of the
shaft at the thrust bearing elevation and the center of runout at the turbine bearing elevation. Verify,
from drawings, the direction of rotation (clockwise or counter-clockwise) of the thrust bearing jack
screw to raise the shoe.
shaft at the thrust bearing elevation and the center of runout at the turbine bearing elevation. Verify,
from drawings, the direction of rotation (clockwise or counter-clockwise) of the thrust bearing jack
screw to raise the shoe.
(iii) Check for free shaft and zero the dial indicators at the turbine guide bearing elevation and at the
thrust bearing elevation.
thrust bearing elevation.
(iv) Start loading with the high shoe, hitting the slugging wrench just hard enough to get 0.0005 to
0.001 inch of movement of the shaft at the turbine bearing. Check for a free shaft. If the shaft is not
free, turn on the high pressure lubrication system and move the shaft at the thrust bearing until the
shaft is free. Subtract the dial indicator readings at the thrust bearing from the readings at the turbine
bearing and record the corrected value, plot the point, and label it with the number of the shoe. Figure
21 is an example of a table for recording the dial indicator readings and a plot of the data.
0.001 inch of movement of the shaft at the turbine bearing. Check for a free shaft. If the shaft is not
free, turn on the high pressure lubrication system and move the shaft at the thrust bearing until the
shaft is free. Subtract the dial indicator readings at the thrust bearing from the readings at the turbine
bearing and record the corrected value, plot the point, and label it with the number of the shoe. Figure
21 is an example of a table for recording the dial indicator readings and a plot of the data.
(v) Moving to the next shoe, hit the slugging wrench to achieve more movement than the first shoe.
Again, check for a free shaft, make it free if it is not, record the readings, and plot the point. Continue
loading each successive shoe, increasing the amount of movement for each shoe until the low shoe is
loaded. After loading the low shoe, the movement should be decreased until the starting shoe is
reached. When adjusting the shoes, never unload a shoe and never skip shoes.
Again, check for a free shaft, make it free if it is not, record the readings, and plot the point. Continue
loading each successive shoe, increasing the amount of movement for each shoe until the low shoe is
loaded. After loading the low shoe, the movement should be decreased until the starting shoe is
reached. When adjusting the shoes, never unload a shoe and never skip shoes.
(vi) The plot of the points will create a spiraling pattern as the shoes are loaded (figure 21). It will
likely take several rounds to move the center of runout to the desired position. Keeping track of the
plot during the loading will help determine how hard or how many times to hit the slugging wrench.
Once the center of runout is at the desired position, all of the shoes should be loaded one more time,
striking each shoe just hard enough to get approximately 0.0005 inch movement. The purpose of the
final round is to ensure that each shoe is equally loaded.
likely take several rounds to move the center of runout to the desired position. Keeping track of the
plot during the loading will help determine how hard or how many times to hit the slugging wrench.
Once the center of runout is at the desired position, all of the shoes should be loaded one more time,
striking each shoe just hard enough to get approximately 0.0005 inch movement. The purpose of the
final round is to ensure that each shoe is equally loaded.
(vii) Take plumb and runout readings again to verify the position of runout. Take hard micrometer
readings at the turbine bearing housing to determine relative position of turbine bearing center.
readings at the turbine bearing housing to determine relative position of turbine bearing center.
(viii) Move shaft so that the centerline of the thrust runner (point 0,0) 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 of guide bearing installation. See section 8 for guide bearing installation
procedures.
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 of guide bearing installation. See section 8 for guide bearing installation
procedures.
Adjustable Shoe Thrust Bearing - Method II
(i) If the plumb of the center of runout is out of tolerance, shim the bridge according to the procedure
in section 7.1.
in section 7.1.
(ii) When the center of runout is plumb, set up dial indicators at the turbine bearing at positions
corresponding to the thrust shoe positions. One indicator will be required for each thrust shoe.
corresponding to the thrust shoe positions. One indicator will be required for each thrust shoe.
(iii) Start at any shoe and strike the slugging wrench. It is important that the same person do all the
loading on the shoes so that they can get a "feel" for the loading.
loading on the shoes so that they can get a "feel" for the loading.