Fan Belt Adjustment—Belt Drive Units

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 33; 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 even with a straightedge placed across the fan and motor sheaves.
Refer to Table 18, below.

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 18, below. 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 Table 18, below.

7. Recheck the belt tension at least twice during the first 2 to 3 days of operation. Belt tension may decrease WARNING until the new belts are “run in”.

                                               

                                       

WARNING:

Information in this article is intended for use by individuals possessing adequate backgrounds of electrical and mechanical experience and who comply with all federal, state, and local laws, rules, orders, or regulations related to the installation, service, or repair of a heating or central air conditioning product. Any attempt to install, service, or repair a heating or central air conditioning product may result in personal injury and/or property damage. The manufacturer or seller cannot be responsible for the interpretation of the information contained herein, nor can it assume any liability in connection with its use.

WARNING:

The following procedure involves working with 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 rotating components cutting and slashing technician which could result in death or serious injury.