Page 153 - Rotating Machinery Pratical Solutions to Unbalance and Misalignment

Advanced Machine Alignment

offset, and there is no angularity.
Continuing working backwards, the rim reading needs to be
multiplied by two, and both readings need their algebraic signs
changed. This results in a final set of indicator readings of plus
two mils (+2) for the rim indicator and zero (0) for the face indi-
cator. These readings should be recorded in the maintenance file
for future reference.
Taking the keystrokes from Figure 8-14 and putting them into
equation form yields:

IB = ± 1 * FB R (8.3)
+
A 2
+
OB = ± 1 * FC R (8.4)
A 2
Where:
F = Face indicator reading.
R = Rim indicator reading.
A = Diameter traced by the face indicator.
B = Distance from the rim indicator stem to the center of the
inboard hold-down bolt.
C = Distance from the rim indicator stem to the center of the
outboard hold-down bolt.
Substituting into these formulas, the results for Example 8-3
yield minus two mils (–2) for the inboard foot and minus seven
mils (–7) for the outboard foot. Once again the calculated thermal
growth is simply added to these readings to obtain the final align-
ment line.
Using Figure 8-16 and converting the key strokes into equa-
tions yield:
R = –R × 2 (8.5)
f
F = –F + R 8.6)
f
Where:
R =Final desired rim indicator reading.
f
F =Final desired face indicator reading.
f