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Fan Belt Adjustment -
Belt Drive Units
WARNING
Rotating Components!
Disconnect all electric power,
including remote disconnects before
servicing. Follow proper lockout/
tagout procedures to ensure the
power can not be inadvertently
energized. Failure to disconnect
power before servicing could result
in death or serious injury.
The fan belts must be inspected
periodically to assure proper unit
operation.
Replacement is necessary if the belts
appear frayed or worn. Units with
dual belts require a matched set of
belts to ensure equal belt length.
When removing or installing the new
belts, do not stretch them over the
sheaves. Loosen the belts using the
belt tension adjustment bolts on the
motor mounting base.
Once the new belts are installed,
using a Browning or Gates tension
gauge (or equivalent) illustrated in
Figure
40; adjust the belt tension as
follows;
1.
To determine the appropriate
belt deflection;
a. Measure the center-to-center
shaft distance (in inches)
between the fan and motor
sheaves.
b. Divide the distance
measured in Step 1a by 64;
the resulting value
represents the amount of
belt deflection that
corresponds to the proper
belt tension.
2.
Set the large O-ring on the belt
tension gauge at the deflection
value determined in Step 1b.
3.
Set the small O-ring at zero on
the force scale of the gauge
plunger.
4.
Place the large end of the gauge
at the center of the belt span;
then depress the gauge plunger
until the large O-ring is even
with the top of the next belt or
RT-SVX21F-EN
Maintenance
even with a straightedge placed
across the fan and motor
sheaves. Refer to Figure 9.
5.
Remove the belt tension gauge.
The small O-ring now indicates a
number other than zero on the
plunger's force scale. This
number represents the force (in
pounds) required to give the
needed deflection.
6.
Compare the "force" scale
reading (Step 5) with the
appropriate "force" value listed
in Table 7. If the "force" reading
is outside the range, readjust the
belt tension.
Note: Actual belt deflection "force"
must not exceed the
maximum "force" value
shown in
Figure
40.
7.
Recheck the belt tension at least
twice during the first 2 to 3 days
of operation. Belt tension may
decrease until the new belts are
"run in" .
Figure 40.
Belt tension gauge
Table 11.
Belt Tension Measurement
and Deflection
Belts
Small
Cross
P.D
Super
Section
Range
Gripbelts
Min.
Max.
3.0 - 3.6
3
4 1/2 3 7/8
A
3.8 - 4.8
3 1/2
5
5.0 - 7.0
4
5 1/2 5
3.4 - 4.2
4
5 1/2 5 3/4
B
4.4 - 5.6
5 1/8
7 1/8 6 1/2
5.8 - 8.8
6 3/8
8 3/4 7 3/8
Monthly Maintenance
Before completing the following
checks, turn the unit OFF and lock the
main power disconnect switch open.
WARNING
Rotating Components!
Disconnect all electric power,
including remote disconnects before
servicing. Follow proper lockout/
tagout procedures to ensure the
power can not be inadvertently
energized. Failure to disconnect
power before servicing could result
in death or serious injury.
Failure to disconnect power before
servicing can cause severe personal
injury or death.
Filters
•
Inspect the return air filters.
Clean or replace them if
necessary. Refer to the unit
Service Facts for filter
information.
Filters
Inspect the return air filters. Clean or
replace them if necessary. Refer to
the unit Service Facts for filter
information.
Return Air Smoke Detector
Maintenance
Airflow through the unit is affected
by the amount of dirt and debris
accumulated on the indoor coil and
filters. To insure that airflow through
the unit is adequate for proper
sampling by the return air smoke
Deflection Force (Lbs.)
Steel Cable
Gripnotch
Gripbelts
Min.
Max.
Min.
Max
5 1/2
3 1/4
4
4 1/2
6 1/4
3 3/4
4 3/4
6 7/8
4 1/4
5 1/4
8
4 1/2
5 1/2
9 1/8
5 3/4
7 1/4
10 1/8 7
8 3/4
41
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