Carrier 17 Start Up & Operation Manual page 73

Example: Face diameter 5 in. (D). Distance between front
and rear holddown bolts 30 in. (L). Net misalign-
ment in elevation .012 in. (M).
30 divided by 5 is 6
6 multiplied by .012 is .072 in.
S = .072 in.
If the larger opening between coupling faces is at the top,
place .072 in. of shim under each rear foot or remove
.072 in. from the front footings to bring the couplings into
angular alignment in elevation.
Tighten the holddown bolts and recheck the net
misalignment.
The height of the shaft above the footings and the dis-
tance the shaft extends beyond the equipment will not affect
the calculations.
Determine the angular adjustment in plan by the same method
of calculation. At this point, however, the procedure should
include a correction for the change in coupling gap which
always occurs in adjusting angular alignment (Fig. 40). By
selecting the proper pivot point (Fig. 41), the coupling gap
can be kept at the dimension specified in the job data.
1. Pivot on the front bolt at the closed side of the couplings
to shorten the gap; pivot on the front bolt at the open side
to lengthen it. It may sometimes be advantageous to pivot
half the required amount on one front footing and half on
the other.
2. Place a dial indicator against the rear foot as indicated in
Fig. 41.
3. Place a screw jack on the other rear foot to move the equip-
ment towards the indicator.
4. Loosen all holddown bolts except the pivot bolt. Turn the
screw jack until the rear end of the equipment moves against
the indicator by the desired amount.
S — Thickness of Shim Required
L — Distance Between Front and
Rear Holddown Bolt in Inches
D — Diameter of Coupling in Inches
M — Net Misalignment in Inches
Fig. 40 — Alignment Formula
Fig. 41 — Adjusting Angular Misalignment in Plan
5. Tighten the holddown bolts and recheck the indicator. If
the reading has changed, loosen the three bolts and re-
adjust. It may be necessary to over or undershoot the de-
sired reading to allow for the effect of bolt tightening.
Correcting Parallel Misalignment
Preparation — Attach the dial indicator to one shaft or cou-
pling hub and place the indicator button on the O.D. of the
other hub. The reach of the dial from one hub to the other
should be parallel to the shafts, and the dial button shaft should
point directly through the center of the shaft on which it rests.
Compress the plunger to about mid-position and set the dial
at zero.
Check the tightness of the dial button and the indicator
linkage by rotating the shaft to which the indicator is at-
tached 360 degrees. The dial should return to zero. Check
for repeatability.
Check for runout by rotating the hub on which the dial
button rests 180 degrees. If the runout exceeds .001 total in-
dicator reading, the hub should be removed and the shaft
checked. Shaft runout must not exceed .001 TIR.
The effect of hub runout can be eliminated by locating a
position on the half coupling where two readings 180 de-
grees apart read zero. Rotate the coupling so that one zero
point is at the top and the other at the bottom when checking
for misalignment in elevation. Place the zero points side to
side in a similar manner when checking for misalignment in
plan.
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