Machinery's Handbook, 31st Edition
2738 SHAFT ALIGNMENT 7th Arrangement.— Place rim and face indicators as shown in Fig. 7a.
A
A f B A f C
2 2 ! ! # ! ! #
F r R r
= + − = + −
f
r
F
R
B
C
Fig. 7a. Dial Indicator Arrangement 7
+
+
+
-
o
+
o
o
o
-
o
+
-
-
-
-
o
+
Fig. 7b. Interpreting Dial Indicator Readings for Indicator Arrangement 7 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 ( − ) 0.002 inch and f = plus (+) 0.001 inch respectively. Solution: This motor is almost in alignment. The upper right block of Fig. 7b corre- sponds to the negative rim and positive face condition. The graph suggests both the front and rear motor feet be lowered, depending on the magnitude of the variables. The formula solution dictates exactly how much the movable unit needs to be lowered at both front and rear shim points. Shims on front and rear feet will be as follows:
A f B
A f C
. 2 0002 2 = + − = − inch =− + − =− ! ! #
. 2 0002 2 = + − = − inch =− + − =− ! ! #
F r
R r
. 12375 0001 14875 . . #
. 12375 0001 4775 . . #
+ −
+ −
. . 0001 0001 0002 . ^
. . 0 001 0 003858 0005 . ^
h
h
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