Bryant 581J-17-28 Service And Maintenance Instructions page 7

Replacing the Motor
1. Turn off all electrical power to the unit. Use approved
lockout/tagout procedures on all electrical power
sources.
2. Remove the cover on the motor connection box.
3. Disconnect all electrical leads to the motor.
4. Loosen the two jack bolt jamnuts on the motor
mounting bracket.
5. Turn the two jack bolts counterclockwise until the
motor assembly moves closer to the blower pulley.
6. Remove the V-belt from the blower pulley and motor
pulley.
CAUTION
!
EQUIPMENT DAMAGE HAZARD
Failure to follow this CAUTION can result in
premature wear and damage to equipment.
Do not use a screwdriver or pry−bar to place the new
V−belt in the pulley groove. This can cause stress on
the V−belt and the pulley, resulting in premature wear
on the V−belt and damage to the pulley.
7. Loosen the four mounting bracket bolts and lock
washers.
8. Remove four bolts, four flat washers, four lock wash­
ers and four nuts attaching the motor mounting plate
to the unit. Discard all lock washers.
9. Remove the motor and motor mounting bracket from
the unit.
10. Remove four bolts, flat washers, lock washers and
single external-tooth lock washer attaching the motor
to the motor mounting plate. Discard all lock washers
and external-tooth lock washer.
11. Lift the motor from the motor mounting plate and set
aside.
12. Slide the motor mounting band from the old motor.
13. Slide the motor mounting band onto the new motor
and set the motor onto the motor mounting plate.
14. Remove the variable pitch pulley from the old motor
and attach it to the new motor.
15. Inspect the variable pitch pulley for cracks and wear.
Replace the pulley if necessary.
16. Secure the pulley to the motor by tightening the pul­
ley setscrew to the motor shaft.
17. Insert four bolts and flat washers through the mount­
ing holes on the motor and into holes on the motor
mounting plate.
18. On one bolt, place a new external-tooth lock washer
between the motor and motor mounting band.
19. Make sure the teeth of the external-tooth lock washer
make contact with the painted base of the motor. This
washer is essential for properly grounding the motor.
20. Install four new lock washers and four nuts on the
bolts on the bottom of the motor mounting plate, but
do not tighten the mounting bolts at this time.
21. Set the new motor and motor mounting bracket back
onto the unit. See Fig. 10.
22. Install four bolts, four flat washers, four new lock
washers and four nuts attaching the motor assembly
to the unit, but do not tighten the mounting bolts at
this time.
23. Install the motor drive V-belt to the motor pulley and
blowerwheel pulley. See CAUTION.
24. Align the motor pulley and blower wheel pulley using
a straight edge. See Fig. 6.
25. Adjust the V-belt tension using the adjustment tool.
26. Turn the two jack bolts clockwise, moving the motor
assembly away from the blower pulley, increasing the
V-belt tension.
27. Tighten the four bolts securing the motor mounting
brackets to the unit. Torque bolts to 120 ± 12 in-lbs
(14 ± 1.4 Nm).
28. Remove the cover on the motor connection box.
29. Re-connect all electrical leads to the motor and re­
place the connection box cover.
30. Re-connect all electrical power to the unit. Remove
lockout tags on all electrical power sources.
31. Start the unit and allow to run for a designated period.
32. Shut off the unit and make any necessary adjustments
to the V-belt tension or the motor and blower wheel
pulley alignment.
BELT
DEFLECTION
Fig. 10 − Adjusting V−belt Tension
Changing Fan Wheel Speed by Changing Pulleys
The horsepower rating of the belt is primarily dictated by
the pitch diameter of the smaller pulley in the drive
system (typically the motor pulley in these units). Do not
install a replacement motor pulley with a smaller pitch
diameter than provided on the original factory pulley.
Change fan wheel speed by changing the fixed fan pulley
(larger pitch diameter to reduce wheel speed, smaller
pitch diameter to increase wheel speed) or select a new
system with both pulleys and matching belt(s).
7
STRAIGHTEDGE
BROWNING BELT
TENSION CHECKER
1/2"
(1.3 cm)
C12093