Machinery's Handbook, 31st Edition
SHAFT ALIGNMENT
2739
8th Arrangement.— Place rim and face indicators as shown in Fig. 8a.
A
A f B A f C
2 2 ! ! # ! ! #
F r R r
= + = +
f
r
F
R
B
C Fig. 8a. Dial Indicator Arrangement 8
-
-
-
-
o
+
o
-
o
o
o
+
+
+
+
-
o
+
Fig. 8b. Interpreting Dial Indicator Readings for Indicator Arrangement 8 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. Depending on the magnitude of the variables, the generic graph gives a mental picture of what the formulas should yield. Example: Calculate the shims necessary for a pump and motor alignment where dimen sions are A =12.375 inches, B =14.875 inches, and C = 47.75 inches. The two indicator dials: r = minus ( − ) 0.042 inch and f = minus ( − ) 0.002 inch respectively. Solution: In Fig. 8b, the top right block conforms to negative rim and negative face val ues. The graph suggests both the front and rear motor feet be lowered. The formula dic- tates exactly how much the movable unit is to be lowered at both front and rear shim points. Shims removed on front and rear feet will be as follows:
A f B
A f C
! ! #
! ! #
F r
R r
2 = + = −
2 = + = −
. 2 0042
. 12375 0002 14875 . . #
. 2 0042
. 12375 0002 4775 . . #
inch + − =− + − =−
inch + − =− + − =−
. . 0021 0002 0023 . ^
. . 0021 00077 0029 . ^
h
h
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