IM 178 / Page 49
Figure 34. LVP variable pitch sheaves
Figure 35b. MVP variable pitch sheaves (type C)
C
E
F
D
A
E
D
B
A
C
E
A
F
D
A
Long
Key
Here
Center Flange
Assembly
End Flange
Two
Locking
Screws
“A”
Barrel Flange
Barrel
18
°
Short
Key
Here
Three Capscrews “B”
Outer
Locking
Ring
Center Flanges
Figure 35a. MVP variable pitch sheaves (type A-B)
Spanner Wrench Hole
Inner Locking
Ring
Gap
Thread
Section A-A
Section A-A
9. Be sure that all keys are in place and that all setscrews and
all capscrews are tight before starting the drive. Check
and retighten all screws and retension the belts after
approximately 24 hours of operation.
MVP variable pitch sheaves
Adjusting:
1. Slack off belt tension by moving the motor toward the
driven shaft until the belts are free from the grooves. For
easiest adjustment, remove the belts.
2. Loosen both locking screws “A” in outer locking ring, but
do not remove them from the sheave. There is a gap of
approximately
1
⁄
32
" (1 mm) between the inner and outer
locking rings. This gap must be maintained for satisfac-
tory 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 are
lined up. Reinsert locking screws “A”, but do not tighten
them until after adjustment is made.
3. Adjust the sheave to the desired pitch diameter by 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 4
3
⁄
4
turns for “A” belts or 6 turns for
“B” belts. Do not open “C” sheaves more than 9
1
⁄
2
turns.
4. Tighten both locking screws “A” in the outer locking ring.
5. Put on the belts and adjust the belt tension. Do not force
belts over grooves. Loosen the belts by adjusting the
motor base closer to the fan shaft.
Caution: Do not loosen any screws other than the two
locking screws “A” in the outer locking ring. These screws
must be tightened securely before the drive is operated.
Two
Locking
Screws
“A”
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