Page 174 - Rotating Machinery Pratical Solutions to Unbalance and Misalignment

Rotating Machinery: Practical Solutions

cold alignment line, shims must be removed. If the line is below
the cold alignment line, shims must be added.

Example 9-1
A machine is measured and the following data are recorded:
A = 10, B =18, C = 48, the stationary indicator STIR = + 8, and the
adjustable indicator ATIR = - 4. What adjustments are required to
properly align the adjustable machine to the stationary machine?

Step 1. First, the stationary reading is divided by two, yielding a
plus four (+4) which is laid off four divisions above the cold align-
ment line, along the stationary indicator line. Note that a scale of
one division per mil was chosen for the vertical axis.

Step 2. Next, the adjustable indicator reading is divided by two
and its algebraic sign changed, yielding a plus two (+2). This
value is laid off two divisions above the cold alignment line, along
the adjustable indicator line. Figure 9-4 shows the completed
graph for the example.
Refer to Figure 8-13 to see this same machine aligned using
the rim and face method. Even though the indicator readings were
different, the answer comes out the same. This illustrates that ei-
ther alignment method will yield the same results. The larger the

S A

IB IB

Stationary
+.5 ▼ Machine C L

Adjustable
Machine C L
(5.5) ▼

Figure 9-4. Reverse Indicator Example Plot