11 8 RT-SVX34C-EN
Maintenance
Fan Belt Adjustment
The Supply 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 installing new belts, do not stretch them over
the sheaves; instead, loosen the adjustable motor-mounting base.
Once the new belts are installed, adjust the belt tension using a Browning or Gates tension gauge
(or equivalent) illustrated in Figure 56.
1. To determine the appropriate belt deflection:
a. Measure the center-to-center distance, in inches, between the fan sheave and the motor
sheave.
b. Divide the distance measured in Step 1a by 64; the resulting value represents the amount
of belt deflection for 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.
4. Place the large end of the gauge on the belt at the center of the belt span. Depress the gauge
plunger until the large O-ring is even with the of the second belt or even with a straightedge
placed across the sheaves.
5. Remove the tension gauge from the belt. Notice that the small O-ring now indicates a value
other than zero on the force scale. This value represents the force (in pounds) required to deflect
the belt(s) the proper distance when properly adjusted.
6. Compare the force scale reading in step 5 with the appropriate “force” value in Figure 57. If the
force reading is outside of the listed range for the type of belts used, either readjust the belt
tension or contact a qualified service representative.
Note: The actual belt deflection force must not exceed the maximum value shown in Figure 57,
p. 120.
7. Recheck the new belt's tension at least twice during the first 2 to 3 days of operation. Readjust
the belt tension as necessary to correct for any stretching that may have occurred. Until the new
belts are “run in”, the belt tension will decrease rapidly as they stretch.
Figure 56. Typical Belt Tension Gauge
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