Machinery's Handbook, 31st Edition
2744 SHAFT ALIGNMENT 13th Arrangement.— In Fig. 13a, the indicator jig is mounted on the static unit and two separate readings are taken from surfaces of the inside of a centrifugal clutch drum on the movable unit.
f
A f B A f C
A
2 2 ! ! # ! ! #
F r R r
= − + = − +
r
R
F
B
C Fig. 13a. Dial Indicator Arrangement 13
RIM: PLUS FACE: MINUS
RIM: ZERO FACE: MINUS
RIM: MINUS FACE: MINUS
RIM: PLUS FACE: ZERO
RIM: MINUS FACE: ZERO
RIM: ZERO FACE: ZERO
RIM: PLUS FACE: PLUS
RIM: ZERO FACE: PLUS
RIM: MINUS FACE: PLUS
Fig. 13b. Interpreting Dial Indicator Readings for Indicator Arrangement 13 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 = 23.0 inches, B = 20.0 inches, and C = 75.0 inches. The indicator readings are r = plus (+) 0.004 inch and f = minus ( − ) 0.003 inch, respectively. Solution: The positive rim and negative face condition is illustrated in the top right block of Fig. 13b. The graph suggests that both the front and rear motor feet needs to be lowered. The formula solution dictates exactly how much the movable unit is to be low- ered at both front and rear shim points:
A f B
A f C
. 2 0004 = − + = − + − =− + − =− 2 inch ! ! # ^
. . = − + = − + − =− + − =− 2 ! ! #
F r
R r
. 230 0003 20 . #
. 2 0004 230 0003 75 0 002 0 00978 0012 . . . inch # ^ h
. . 0002 00026 0005 .
h
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