points side to side in a sim il ar manner when checking f or misalignment in plan.
Measurement
— With dial set at zero in the t op position, rotate the s ha ft to which the
indicator is at tached 180 degrees . If the dial reading is plu s, the shaft on w hich the button rests
is low. If the reading is minu s, the shaft on which the bu tton rests is high.
Never accept a s ingle reading. Look for repeat ability. Rotate t he shaft severa l times to see i f
the reading remains the same. It is good practice t o r ev er s e the procedure and read from z er o
at the bott om .
Always rotate the shafts in the same direction whe n taking readings. Backla sh in the coupling
teeth could cause some dif ferences.
Adjustment
— Divide the total indicato r reading by two to obtain th e exact amount of shaft
offset. As illu strated in Figu re 42, the indicator will r ea d the total of A plus B but the re qui red
shaft adjustment is only ha lf of this as indicated by C.
Add or remove identical amounts of shims at all footin gs to bring the shaft to th e pr op er
elevation. Tighten all the holddown bolts and r ec he ck the readings. Paral lel alignment must be
within .002 TIR.
To correct paral lel misalignmen t in plan, use a screw jack and dial indicator as shown in
Figure 42. With a front holddo wn bolt as the pivot, move th e rear of the equipment ov er . Then,
with the rear holddown bolt
on the same side
acting as the pivot, move the front end of the
equipment over by the sam e am o unt.