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Handbook of Turbomachinery Second Edition Revised - Ventech!

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pivots incorporated in this bearing configuration make it truly self-aligning<br />

(Fig. 62).<br />

However, there are some disadvantages related to tilt pad bearings.<br />

Normally, they have higher power losses and operate at higher temperatures<br />

for a given set <strong>of</strong> supply oil flow conditions. Tilt pad bearings operate at a<br />

smaller minimum film thickness during maintenance inspections. If properly<br />

designed, however, these disadvantages can be minimized.<br />

For the thrust-bearing application, tilt pad bearings are <strong>of</strong>ten utilized<br />

because <strong>of</strong> their superior characteristics relating to alignment and thermal<br />

distortion. This is accomplished because each pad can toll and pitch to<br />

adjust to misalignment and thermal distortion. Also, for fully equalized<br />

thrust bearings, the linkage behind the pads ensures good load sharing<br />

among all the pads. One manufacturer has had success using a copper<br />

material, which helps compensate for deleterious thermal effects in their<br />

fixed thrust-bearing configurations.<br />

Figure 62 Steam turbine speed and load control system utilizing a flyball governor<br />

connected to a hydraulic relay piston combination.<br />

Copyright © 2003 Marcel Dekker, Inc.

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