Model NYB
6.Always loosen tension enough to install belts without stretching, see figure 4.
Belts
| Do not force belt(s). Forcing the | |
Figure 4 | belt(s) will break the cords and | |
cause belt failure | ||
|
7.For units with two groove pulleys, adjust so the tension is equal in both belts.
8.If adjustments are made, it is very important to check the pulleys for proper alignment. Misaligned pulleys lead to excessive belt wear vibration, noise and power loss, see figure 5.
Figure 5
9.Belt tension can be adjusted by loosening four fasteners on the drive frame, see figure 6. This allows the motor plate to slide on the drive frame angles for proper positioning.
Fasteners
(4) *Fasteners
*Identical fasteners on opposing side must also be loosened.
Figure 6
10.Belt tension should be adjusted to allow 1/64 inch (0.397 mm) of deflection per inch of belt span. For example, a 15 inch (381 mm) belt span should have 15/64 inch (0.234 mm) (or about 1/4 inch (6 mm)) of deflection with moderate thumb pressure at
13.The adjustable motor pulley is factory set for the RPM specified. Speed can be increased by closing or decreased by opening the adjustable motor pulley. Two groove variable pitch pulleys must be adjusted an equal number of turns open or closed.
14.Any increase in speed represents a substantial increase in the horsepower required by the unit.
15.Motor amperage should always be checked to avoid serious damage to the motor when speed is varied.
WARNING
The fan has been checked for mechanical noises at the factory prior to shipment. If mechanical noise should develop, suggested corrective actions are offered in the Troubleshooting section.
IMPORTANT
Over tightening will cause excessive bearing wear and noise. Too little tension will cause slippage at
Operation: NYD/NYB
1.Before starting or operating fan, check all fasteners for tightness. In particular, check the setscrews in wheel hub (and pulleys, if applicable).
2.While in the OFF position or before connecting the fan to power, turn the fan wheel by hand to be sure it is not striking the venturi or any obstacle.
3.Start the fan and shut it off immediately to check rotation of the wheel with directional arrow in the motor compartment, see figure 3 on page 3.
4.When the fan is started, observe the operation and check for any unusual noises.
5.With the system in full operation and all ductwork attached, measure current input to the motor and compare with the nameplate rating to determine if the motor is operating under safe load conditions.
6.Keep inlets and approaches to fan clean and free from obstruction.
Inspection: NYD/NYB
Inspection of the fan should be conducted at the first 30 minute and 24 hour intervals of satisfactory operation.
Deflection
Figure 7
30 Minute Interval
Inspect bolts, setscrews and motor mounting bolts. Adjust and tighten as necessary.
24 Hour Interval
Check all internal components. On NYB unit only, inspect belt alignment and tension. Adjust and tighten as necessary.
4
Models NYD & NYB •
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