Page 70 - Steam Turbines Design, Applications, and Rerating

Chapter
3

Bearings for Mechanical

Drive Turbines

3.1 Journal Bearings for Industrial
Turbomachinery
The journal bearing designs described in this chapter are common to
many types of industrial turbomachinery, including steam turbines.
The types of bearings most commonly found in turbomachinery
include:
■ Plain cylindrical
■ Axial groove
■ Pressure dam
■ Lemon bore or elliptical
■ Offset half
■ Multilobe
■ Tapered land
■ Tilting-pad

The reason for such a large selection of bearings is that each of these
types has unique operational characteristics that render it more suit-
able for one particular application compared to another.
The fundamental geometric parameters for all journal bearings are
diameter, pad arc length, length-to-diameter ratio, and running clear-
ance. For the bearing types consisting of multiple pads, there are also
variations in the number of pads, pad preload, pad pivot offset, and
bearing orientation (on or between pads). In addition to the geometric
parameters, there are several important operating parameters. The
key operating parameters are oil type, oil inlet temperature, oil inlet
pressure, rotating speed, gravity load at the bearing, and applied exter-

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