Page 177 - Rotating Machinery Pratical Solutions to Unbalance and Misalignment

Reverse Indicator Alignment

graph the results and calculate the solution. Again the calculator
should provide an exact solution, while the graph should be
within less than 1 mil of the calculator.
The moving of the machine during the horizontal alignment
was discussed in the rim and face chapter, and should be re-
viewed. Since this method employs two rim indicators, they can
be set to 1/2 their readings and observed as the machine is
moved. Note however that both indicators should be set to 1/2
their value while in the 3 o’clock position only. This means that
when the indicator is positioned at 9 o’clock, it will read minus 1/
2 its 3 o’clock reading. With this, the machine can be moved until
both indicators read zero. This method can be used on small
machines or machines that are easy to move in a controlled man-
ner. However, measuring the movement of the machine at each
foot is the recommended method, and will prove more accurate in
most applications.
The best solution is to mount dial indicators to the base so
that they read against the feet. Set both indicators to zero and use
a controlled method of moving the machine. Move the machine
until the required readings are observed on the dial indicators. A
final set of both vertical and horizontal readings must be taken to
assure the vertical alignment was not upset and that the correct
adjustment was made in the horizontal direction.

THERMAL GROWTH

Thermal growth is basically handled the same as it was for
the rim and face method. Again, the most desirable method is hot
readings obtained from the machine after it has been aligned cold.
Use the same procedures to obtain a set of hot readings, and plot
their values over the cold graph. Note if a calculator solution is
desired, calculate the results of the hot run as with any other run,
and simply add the two runs together algebraically to obtain the
final results.
Remember, it is the objective to misalign the machine when
cold to assure proper alignment under normal operating condi-