7
Fig. 11 —
Replacing Belt Driven Motor
Replacing the Motor
1. Turn off all electrical power to the unit. Use approved lock
-
out/tag-out 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.
7. Loosen the four mounting bracket bolts and lock washers.
8. Remove four bolts, four flat washers, four lock washers and
four nuts attaching the motor mounting plate to the unit. Dis
-
card 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 pulley set
-
screw to the motor shaft.
17. Insert four bolts and flat washers through the mounting 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. 11.
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 blower
wheel pulley. See CAUTION.
24. Align the motor pulley and blower wheel pulley using a
straight edge. See Fig. 8.
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.-lb (14 ± 1.4 Nm).
28. Remove the cover on the motor connection box.
29. Re-connect all electrical leads to the motor and replace 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.
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).
Before changing pulleys to increase fan wheel speed, check the
fan performance at the target speed and airflow rate to determine
new motor loading (bhp). Use the fan performance tables or use
the Packaged Rooftop Builder software program. Confirm that the
motor in this unit is capable of operating at the new operating con
-
dition. Fan shaft loading increases dramatically as wheel speed is
increased.
CAUTION
EQUIPMENT DAMAGE HAZARD
Failure to follow this CAUTION can result in premature wear
and damage to equipment.
Do not use a screwdriver or a 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.
BLOWER PULLEY
V-BELT
MOTOR PULLEY
MOTOR
MOTOR MOUNTING
BRACKET BOLTS (4)
MOTOR MOUNTING
BRACKET (2)
JACK BOLT JAM NUT (2)
JACK BOLT (2)
CAUTION
EQUIPMENT DAMAGE HAZARD
Failure to follow this caution can result in equipment damage.
Drive packages cannot be changed in the field. For example: a
standard drive cannot be changed to a high static drive. This
type of change will alter the unit’s certification and could re
-
quire heavier wiring to support the higher amperage draw of
the drive package.
Summary of Contents for WeatherMaker 50TC 17-30 Series
Page 34: ...34 Fig 48 RTU Open Overlay for Economizer Wiring ...
Page 35: ...35 Fig 49 VFD Overlay for W2770 Controller Wiring ...
Page 80: ...80 Fig C 50TC 17 28 Control Wiring Diagram APPENDIX D WIRING DIAGRAMS ...
Page 81: ...81 Fig D 50TC 30 Control Wiring Diagram 208 230 3 60 Units APPENDIX D WIRING DIAGRAMS ...
Page 82: ...82 Fig E 50TC 30 Control Wiring Diagram 460 3 60 575 3 60 Units APPENDIX D WIRING DIAGRAMS ...
Page 83: ...83 Fig F 50TC 17 30 Power Wiring Diagram 208 230 3 60 Units APPENDIX D WIRING DIAGRAMS ...
Page 84: ...84 Fig G 50TC 17 30 Power Wiring Diagram 460 3 60 575 3 60 Units APPENDIX D WIRING DIAGRAMS ...
Page 89: ...89 Fig L 50TC PremierLink System Wiring Diagram APPENDIX D WIRING DIAGRAMS ...
Page 90: ...90 Fig M 50TC RTU Open Wiring Diagram APPENDIX D WIRING DIAGRAMS ...
Page 91: ...91 Fig N 50TC SAV VFD System Wiring Diagram APPENDIX D WIRING DIAGRAMS ...
Page 93: ......
