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www.DaikinApplied.com 37
IM 777-8 • Skyline Air Handler
Fan Drive Belt Adjustment
WARNING
Moving belt and fan can cause severe personal injury or
death.
During installation and filter maintenance:
• Verify that the belt and fan guards on plenum fan units are
always in place.
• Lock and tag out fans to prevent accidental start up.
• Do not enter the filter compartment until the fan is completely
stopped.
• Use approved equipment for reaching filters located above
normal reach. Do no step on filter frames or unit components.
• Floor surfaces must be dry and free of oil or grease.
General Rules of Tensioning
1. The ideal tension is the lowest tension at which the belt
does not slip under peak load conditions.
2.
Check tension frequently during the first 24 to 48 hours
of operation.
3. Over tensioning shortens belt and bearing life.
4. Keep belts free from foreign material that can cause
slippage.
5. Inspect V-drive on a periodic basis. Adjust tension if
the belt is slipping. Do not apply belt dressing. This can
damage the belt and cause early failure.
Tension Measurement Procedure
1. Measure the belt span. See
Figure 51
.
2. Place belt tension checker squarely on one belt at the
center of the belt span. Apply force to the checker,
perpendicular to the belt span, until the belt deflection
equals belt span distance divided by 64. Determine the
force applied while in this position.
3. Compare this force to the values in
Table 29
.
Figure 51: Drive Belt Adjustment
Table 29: Belt Deflection Force (per Browning
Specifications)
Cross
section
Small sheave
diameter (in)
Number of belts (deflection force lbs)
1
2
3 +
min
max
min
max
min
max
A, AX
0.0 to 3.5
3.0
5.0
2.5
4.0
2.0
3.5
3.6 to 4.4
3.5
5.0
3.0
4.5
2.0
4.0
4.5 +
4.0
5.5
3.0
5.0
2.5
4.5
B, BX
0.0 to 5.4
5.5
8.0
4.5
7.0
3.5
5.5
5.5 to 7.6
5.5
8.5
4.5
7.5
3.5
5.5
7.7 +
6.5
9.0
5.0
8.0
4.0
6.5
5V, 5VX
0.0 to 8.5
7.0
11.0
5.5
9.0
4.0
7.0
8.6 to 12.0
8.5
13.0
6.5
10.5
5.0
8.0
12.1 +
10.0
15.0
7.5
11.5
5.5
9.0
Belt span
Deflection = Belt span
64
