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7
Fig. 8 — Typical Belt Drive Motor Mounting
Variable Frequency Drive (VFD)
For units equipped with a VFD factory installed option (FIOP),
refer to the following supplement: “Variable Frequency Drive
(VFD) Installation, Setup and Troubleshooting.”
Belt
Check the belt condition and tension quarterly. Inspect the belt
for signs of cracking, fraying, or glazing along the inside sur-
faces. Check belt tension by using a spring-force tool, such as
Browning’s “Belt Tension Checker” (P/N: 1302546) or equiva-
lent tool; tension should be 6 lbs at a
5
/
8
-in. (1.6 cm) deflection
when measured at the centerline of the belt span. This point is
at the center of the belt when measuring the distance between
the motor shaft and the blower shaft.
NOTE: Without the spring-tension tool, place a straight edge
across the belt surface at the pulleys, then push down on the belt at
mid-span using one finger until a
1
/
2
-in. (1.3 cm) deflection is
reached. See Fig. 9.
Adjust belt tension by loosening the motor mounting plate
front and rear bolts and sliding the plate toward the fan (to re-
duce tension) or away from fan (to increase tension). Ensure
the blower shaft and the motor shaft are parallel to each other
(pulleys aligned). When finished, tighten all bolts and torque to
65 to 70 in.-lb (7.4 to 7.9 Nm).
Fig. 9 — Checking Blower Motor Belt Tension
REPLACING THE BELT
NOTE: Use a belt with same section type or similar size. Do not
substitute an FHP-type belt. When installing the new belt, do not
use a tool (screwdriver or pry bar) to force the belt over the pulley
flanges; this will stress the belt and cause a reduction in belt life.
Damage to the pulley can also occur.
.
Use the following steps to replace the V-belt. See Fig. 8.
1. Loosen the front and rear motor mounting plate bolts.
2. Push the motor and its mounting plate towards the blower
housing as close as possible to reduce the center distance
between fan shaft and motor shaft.
3. Remove the belt by gently lifting the old belt over one of
the pulleys.
4. Install the new belt by gently sliding the belt over both
pulleys and then sliding the motor and plate away from the
fan housing until proper tension is achieved.
5. Check the alignment of the pulleys; adjust if necessary.
6. Tighten all bolts and torque to 65 to 70 in.-lb (7.4 to
7.9 Nm).
7. Check the tension after a few hours of runtime and read-
just as required.
Adjustable-Pitch Pulley on Motor
The motor pulley is an adjustable-pitch type that allows a ser-
vicer to implement changes in the fan wheel speed to match as-
installed ductwork systems. The pulley consists of a fixed
flange side that faces the motor (secured to the motor shaft)
and a movable flange side that can be rotated around the fixed
flange side that increases or reduces the pitch diameter of this
driver pulley. See Fig. 10.
Fig. 10 — Supply-Fan Pulley Adjustment
As the pitch diameter is changed by adjusting the position of
the movable flange, the centerline on this pulley shifts laterally
(along the motor shaft). This creates a requirement for a re-
alignment of the pulleys after any adjustment of the movable
flange. Reset the belt tension after each realignment.
Inspect the condition of the motor pulley for signs of wear.
Glazing of the belt contact surfaces and erosion on these sur-
faces are signs of improper belt tension and/or belt slippage.
Replace pulley if wear is excessive.
BLOWER PULLEY
V--- BELT
MOTOR
PULLEY
MOTOR MOUNTING
PLATE
MOTOR
MOUNTING
BOLTS (4)
BROWNING BELT
TENSION CHECKER
STRAIGHTEDGE
1/2”
(1.3 cm)
BELT
DEFLECTION
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.
STRAIGHT EDGE
MUST BE PARALLEL
WITH BELT
SETSCREWS
MOTOR AND
FANSHAFTS
MUST BE
PARALLEL
FIXED FLANGE
MOVABLE
FLANGE
SINGLE - GROOVE
FAN PULLEY
MOTOR PULLEY
Summary of Contents for 50HCQ04---12
Page 86: ...86 APPENDIX E WIRING DIAGRAMS cont Fig C 50HCQA04 A05 Control Wiring Diagram 575 3 60...
Page 88: ...88 APPENDIX E WIRING DIAGRAMS cont Fig E 50HCQ 06 Control Wiring Diagram 575 3 60...
Page 93: ...93 APPENDIX E WIRING DIAGRAMS cont Fig J 50HCQ 04 05 06 Power Wiring Diagram 208 230 1 60...
Page 94: ...94 APPENDIX E WIRING DIAGRAMS cont Fig K 50HCQ 04 05 06 Power Wiring Diagram 208 230 3 60...
Page 95: ...95 APPENDIX E WIRING DIAGRAMS cont Fig L 50HCQ 04 05 06 Power Wiring Diagram 460 3 60...
Page 96: ...96 APPENDIX E WIRING DIAGRAMS cont Fig M 50HCQ 04 05 06 Power Wiring Diagram 575 3 60...
Page 100: ...100 APPENDIX E WIRING DIAGRAMS cont Fig Q 50HCQ 12 Power Wiring Diagram 208 230 3 60...
Page 101: ...101 APPENDIX E WIRING DIAGRAMS cont Fig R 50HCQ 12 Power Wiring Diagram 460 3 60 575 3 60...
Page 102: ...102 APPENDIX E WIRING DIAGRAMS cont Fig S 50HCQ PremierLink Control Diagram...
Page 103: ...103 APPENDIX E WIRING DIAGRAMS cont Fig T 50HCQ RTU Open Control Diagram...