A
PD MANUAL
IOM-39
26 of 36
Aug 99 R1
NOTE:
If
belts
are
too
tight
or
improperly
aligned,
the
life
expectancy
of
the
motor(s),
fan
bearings
and
belt(s)
are
reduced.
Alignment:
Pulleys
must
be
aligned
to
within
1/16”
per
foot
(1mm
per
760mm)
of
span.
FOR
FANS
EQUIPPED
WITH
SPIDER
BRACKETS:
A
properly
adjusted
V
‐
belt
rides
the
inside
of
the
pulley
faces.
Because
the
sides
of
the
belt
wedge
in
the
pulleys,
the
V
‐
belt
does
not
have
to
be
extremely
tight.
It
should
be
as
loose
as
possible
without
slipping
in
the
pulley
grooves.
Belt
deflection:
3/4
“
(19mm)
for
each
foot
(300mm)
of
span
between
the
pulleys.
FOR
FANS
EQUIPPED
WITH
PILLOW
BLOCK
BEARINGS:
Belt
Deflection:
Allow
1/64”
(0.4mm)
of
deflection
for
each
1”
(25.4
mm)
of
span
length.
Caution:
Excessive
belt
tension
is
the
most
frequent
cause
of
belt
wear,
bearing
wear
and
noise.
SET
SCREWS
Check
set
screws
on
fan
wheel,
fan
bearings,
fan
and
motor
pulleys
for
looseness
on
the
shaft.
Tighten
where
required.
IT
IS
IMPORTANT
TO
PERFORM
THIS
CHECK
BEFORE
INITIAL
START
‐
UP,
AFTER
A
RUN
‐
IN
PERIOD
OF
2
WEEKS
AND
THEN
ON
4
MONTH
INTERVALS.
Caution:
Caution:
overtightening
set
screws
can
damage
bearings.
DEFLECTION
SPAN
