Machinery's Handbook, 31st Edition
SHAFT ALIGNMENT
2747
16th Arrangement.— Place rim and face indicators as shown in Fig. 16a.
f
r
A
A f B A f C
2 2 ! ! # ! ! #
F r
= +
R r
= +
F
R
B
C
Fig. 16a. Dial Indicator Arrangement 16
-
-
- -
o
+
RIM: PLUS FACE: MINUS
RIM: ZERO FACE: MINUS
RIM: MINUS FACE: MINUS
- o
o o
+ o
RIM: PLUS FACE: ZERO
RIM: ZERO FACE: ZERO
RIM: MINUS FACE: ZERO
- +
+ o
+ +
RIM: PLUS FACE: PLUS RIM: MINUS FACE: PLUS Fig. 16b. Interpreting Dial Indicator Readings for Indicator Arrangement 16 RIM: ZERO FACE: PLUS 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 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 = 16.0 inches, B = 26.0 inches, and C = 54.0 inches. The two indicator dials read r = minus ( − ) 0.002 inch and f = minus ( − ) 0.006 inch respectively. Solution: The rim and face numbers indicate that the whole movable machine is one mil high (from the rim indicator, r ⁄ 2 = 0.002 ⁄ 2 = 0.001), and the angularity from the face indica- tor say that for every 16 inches of axial length from the rim indicator there is an upward incline toward the rear of 0.006 inch. In Fig. 16b, locate the block with negative rim and negative face values. The graph suggests both the front and rear motor feet be lowered. The formula solution dictates that the movable unit is to be lowered at both front and rear shim points:
A f B
A f C
! ! #
! ! #
F r
R r
2 = + = −
2 = + = −
. 2 0002
. 16 0006 26 #
. 2 0002
. 16 0006 540 . #
inch + − =− + − =−
inch + − =− + − =−
. . 0 001 0 00975 0011 . ^
. . 0 001 0 02025 0021 . ^
h
h
Rim and Face Method Extended to Motors with Extra Feet.— Fig. 17 illustrates an alignment problem that is complicated by the fact that the motor has ten feet. The indicator
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