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Adjusting:
Slack off all belt tension by moving the motor toward the
1
driven shaft until the belts are free from the grooves. For
easiest adjustment, remove the belts.
Loosen setscrews D.
2
Loosen but do not remove capscrews E.
3
Remove key F. This key projects a small amount to
4
provide a grip for removing.
Adjust the pitch diameter by opening or closing the
5
movable flange by half or full turns. Note that two-
groove sheaves are supplied with both grooves set at the
same pitch diameter. Both movable flanges must be
moved the same number of turns to ensure the same
pitch diameter for satisfactory operation. Do not
open sheaves more than five turns for A belts or six
turns for B belts.
Replace key F.
6
Tighten setscrews D and capscrews E.
7
Put on the belts and adjust the belt tension. Do not force
8
belts over grooves. Loosen the belts by adjusting the
motor base closer to the fan shaft.
Before starting the drive, make sure that all keys are in
9
place and all setscrews and all capscrews are tight.
Check and retighten all screws and re-tension the belts
after approximately 24 hours of operation.
McQuay IM 987
Check, Test, and Start Procedures
MVP Variable Pitch Sheaves
Adjusting:
Slack off belt tension by moving the motor toward the
1
driven shaft until the belts are free from the grooves. For
easiest adjustment, remove the belts.
Loosen both locking screws A in outer locking ring, but
2
do not remove them from the sheave. There is a gap of
approximately 1/2" (1 mm) between the inner and outer
locking rings. This gap must be maintained for
satisfactory locking of the sheave.
If locking screws A are removed by accident and the gap
is lost, screw the outer locking ring down until it touches
the inner locking ring. Then, back off the outer ring 1/2
to 3/4 turn until the inner and outer ring screw holes line
up. Reinsert locking screws A, but do not tighten them
until after adjustment is made.
Adjust the sheave to the desired pitch diameter by
3
turning the outer locking ring with a spanner wrench.
Any pitch diameter can be obtained within the sheave
range. One complete turn of the outer locking ring will
result in a 0.233" (6 mm) change in pitch diameter. Do
not open A-B sheaves more than four 3/4 turns for A
belts or 6 turns for B belts. Do not open C sheaves
more than nine 1/2 turns.
Tighten both locking screws A in the outer locking ring.
4
Put on the belts and adjust the belt tension. Do not force
5
belts over grooves. Loosen the belts by adjusting the
motor base closer to the fan shaft.
Do not loosen any screws other than the two locking screws (A)
in the outer locking ring. Before operating the drive, securely
tighten these screws.
CAUTION
101
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