Machinery's Handbook, 31st Edition
SHAFT ALIGNMENT 2733 2nd Arrangement.— Rim and face indicators are placed as shown in Fig. 2a. This ar- rangement is commonly used when the space between couplings is limited.
A f B A f C
A
2 2 ! ! # ! ! #
F r R r
= − + − = − + −
f
r
R
F
B
C
Fig. 2a. Dial Indicator Arrangement 2
+
-
o
o
o
o
-
o
+
-
-
-
-
o
+
Fig. 2b. Interpreting Dial Indicator Readings for Indicator Arrangement 2 Indicators are shown in the reading position. Solid lines represent the desired location for the dashed lines (movable unit). The plus, minus, and zero readings on the indicators are represented by one of these nine scenarios. The generic graph gives a picture of what the formulas should yield. Example: Calculate the shims necessary for a pump and motor alignment where dimen sions are A = 4.75 inches, B = 7.75 inches, and C = 17.25 inches. The two indicator dials read r = plus (+) 0.004 inch and f = minus ( − ) 0.022 inch respectively. Solution: The lower right block in Fig. 2b corresponds to a positive rim reading and a negative face. The diagram indicates that shims will be required under both the front and rear feet. Calculations confirm this, as follows:
. 2 = − + − = − + − − =− + = . . 0002 0036 0034 . . A f B 2 0004 inch ! ! #
. 2 0004 = − + − = − + − − =− + = . . A f C 2 ! ! #
F r
R r
. 475 0022 775 . #
. 475 0022 1725 . #
. 0 002 0 07989 0078 . inch
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