Machinery's Handbook, 31st Edition
SHAFT ALIGNMENT
2735
4th Arrangement.— Place rim and face indicators as shown in Fig. 4a.
r
f
A
A f B A f C
2 2 ! ! # ! ! #
F r R r
= + = +
F
R
B
C
Fig. 4a. Dial Indicator Arrangement 4
-
o
- +
-
-
-
o
+
o
o
o
-
o
+
+
+
+
Fig. 4b. Interpreting Dial Indicator Readings for Indicator Arrangement 4 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 = 3.5 inches, B = 8.25 inches, and C = 19.25 inches. The two indicators read r = minus ( − ) 0.011 inch and f = minus ( − ) 0.019 inch respectively. Solution: According to the top left block in Fig. 4b, the negative rim and negative face values indicate that the motor needs to have shims removed from beneath both the front and rear feet. The calculations that follow confirm that 0.05 inch needs to be removed from beneath the front feet, and 0.11 inch from below the rear feet. This adjusting may be diffi cult if the motor is sitting on its base without shims.
A f B + −
A f C
! ! #
! ! #
F r
R r
2 = + = −
2 = + = −
. 2 0011
. 35 0019 825 . . #
. 2 0011
. 35 0019 1925 . . #
+ − + − ^
. . 0 0055 0 04479 0050 . inch + − ^
. . 0 0055 0 1045 0110 . inch
h
h
=− =−
=− =−
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