Page 136 - Rotating Machinery Pratical Solutions to Unbalance and Misalignment

Rotating Machinery: Practical Solutions

main the same for both sets of measurements.

A= 10 inches.
B = 22 inches.
C= 45-1/2 inches.

The readings for the reverse indicator method are S = minus
four (–4) and M = zero (0). The rim and face readings are R =
minus 4 (–4) and F = plus two (+2). Plot the two methods and
assure the same movements are indicated.
For the reverse indicator method, both readings are divided
by two and the adjustable machine indicator has its algebraic sign
changed. This yields S = 2 and M = 0. These two points are
marked off on a graph A distance apart. The two points are con-
nected, and this line is extended to intersect two lines representing
the inboard and outboard foot locations. The result is to add 4.5
mils to the inboard foot and 13 mils to the outboard foot.
For the rim and face method, the rim reading is treated ex-
actly as the adjustable reading in the reverse indicator method.
That is, it is divided by two and has its algebraic sign changed.
The face reading simply has its algebraic sign changed. This re-
sults in R = plus two (+2) and F = minus two (–2). The corrected
rim reading is plotted the same as the stationary reading in the
reverse indicator method. A horizontal line is now constructed to

Reverse Indicator Rim & Face

S M IB OB R F IB OB

+2 • 0 +2 • –2
• •

4.5 4.5
13.0 13.0

S = –4 M = 0 R = –4 F = +2

Figure 8-11. Plotting the Alignment Results