Machinery's Handbook, 31st Edition
SHAFT ALIGNMENT 2743 12th Arrangement.— The set up in Fig. 12a could be one indicator with two stems, or one indicator taking separate face and rim readings at the same location.
f
A
A f B A f C
2 2 ! ! # ! ! #
F r R r
= + = +
r
R
F
B
C Fig. 12a. Dial Indicator Arrangement 12
RIM: ZERO FACE: MINUS
RIM: PLUS FACE: MINUS
RIM: MINUS FACE: MINUS
RIM: MINUS FACE: ZERO
RIM: ZERO FACE: ZERO
RIM: PLUS FACE: ZERO
RIM: PLUS FACE: PLUS RIM: MINUS FACE: PLUS Fig. 12b. Interpreting Dial Indicator Readings for Indicator Arrangement 12 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 = 23.0 inches, B = 41.0 inches, and C = 96.0 inches. The two indicator readings are r = plus (+)0.004 inch and f = minus ( − )0.003 inch, respectively. Solution: For practical purposes, this unit is already within tolerance by most standards. However, the block in the upper left corner of Fig. 12b illustrates the positive rim and neg ative face condition. The graph suggests both the front and rear motor feet be lowered. Removal of 0.003 inch of shim at the front and 0.011 inch at the rear feet will reduce mis alignment to less than a mil on the next reading.
A f B
A f C
! ! #
! ! #
F r
R r
. 2 = + = 2 0004
. 2 = + = 2 0004
. 230 0003 41 . #
. 230 0003 96 . #
inch + − = + − =−
inch + − = + − =−
. 0002 0005 0003 . . ^
. 0002 0013 0011 . . ^
h
h
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