Determine Fan
Speed
WARNING Rotating Components!
During installation, testing, servicing and troubleshooting of this product it may be necessary to measure the speed of rotating components. Have a qualified or licensed service individual who has been properly trained in handling exposed rotating components, perform these tasks. Failure to follow all safety precautions when exposed to rotating components could result in death or serious injury.
Fan speed can be determined using a
Check unit vibration if the fan speed is changed more than 5 percent from the original designed speed, or if parts such as shafts, fan wheels, bearings, or other drive components are replaced. Do not exceed the maximum fan speed.
Pay particular attention to any vibration, noise, or overheating of the motor and fan bearings; however, note that bearings may run warm during break in.
Sheave Alignment
Align the fan and motor sheaves using a straightedge. The straightedge must be long enough to span the distance between the outside edges of the sheaves. When the sheaves are aligned, the
Startup
Figure 48. Proper drive alignment
Table 4. Fan and drive compound torque settings (inches)
Screw Size | Hex Key | Square Head | Hex Head | Torque | Torque |
1/4 | 1/8 | 3/8 | 7/16 | ||
5/16 | 5/32 | 1/2 | 1/2 | ||
3/8 | 3/16 | 9/16 | 9/16 | ||
7/15 | 7/32 | 5/8 | 5/8 | ||
1/2 | 1/4 | 3/4 | 3/4 | ||
5/8 | 5/16 | 15/16 | 15/16 |
straightedge will touch both sheaves at points A through D (see
Figure 48) to confirm the shaft is parallel. For uneven width sheaves, place a string in the center groove of both sheaves and pull tight. Adjust the sheaves and tighten the sheave set screws to the proper torque given in Table 4.
Multibelt Check
Tighten the belts slightly and rotate the drive several times.
On multiple belt drives, ensure the force of deflection is approximately the same on each belt by pushing each belt in an equal distance at a point halfway from each sheave (see Figure 48). If this force is not the
same for each belt, the motor and fan shaft are not parallel. Realign as required. After realignment, tighten the belts again to the standard belt tensioning specifications. If the force is still not the same for all belts, the belts or sheaves are worn and must be replaced.
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