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Supply Fan (Belt--Drive)
The supply fan system consists of a forward--curved
centrifugal blower wheel on a solid shaft with two
concentric type bearings, one on each side of the blower
housing. A fixed--pitch driven pulley is attached to the fan
shaft and an adjustable--pitch driver pulley is on the
motor. The pulleys are connected using a “V” type belt.
(See Fig. 5.)
C07087
Fig. 5 -- Belt Drive Motor Mounting
Belt
Check the belt condition and tension quarterly. Inspect the
belt for signs of cracking, fraying or glazing along the
inside surfaces. Check belt tension by using a spring--force
tool (such as Browning’s Part Number “Belt Tension
Checker” or equivalent tool); tension should be 6--lbs at a
5/8--in. 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 deflect the
belt at mid--span using one finger to a 1/2--in. deflection.
Adjust belt tension by loosening the motor mounting plate
front bolts and rear bolt and sliding the plate toward the
fan (to reduce tension) or away from fan (to increase
tension). Ensure the blower shaft and the motor shaft are
parallel to each other (pulleys aligned). Tighten all bolts
when finished.
To replace the belt:
1. Use a belt with same section type or similar size. Do
not substitute a “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.
2. Loosen the motor mounting plate front bolts and rear
bolts.
3. 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.
4. Remove the belt by gently lifting the old belt over
one of the pulleys.
5. 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.
6. Check the alignment of the pulleys, adjust if
necessary.
7. Tighten all bolts.
8. Check the tension after a few hours of runtime and
re--adjust as required.
Adjustable--Pitch Pulley on Motor
The motor pulley is an adjustable--pitch type that allows a
servicer 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. 6.)
C07075
Fig. 6 -- 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 realignment of the pulleys after any
adjustment of the movable flange. Also reset the belt
tension after each realignment.
Check the condition of the motor pulley for signs of wear.
Glazing of the belt contact surfaces and erosion on these
surfaces are signs of improper belt tension and/or belt
slippage. Pulley replacement may be necessary.
To change fan speed:
1. Shut off unit power supply.
2. Loosen belt by loosening fan motor mounting nuts.
(See Fig. 5.)
3. Loosen movable pulley flange setscrew. (See Fig. 6.)
4. Screw movable flange toward fixed flange to increase
speed and away from fixed flange to decrease speed.
Increasing fan speed increases load on motor. Do not
exceed maximum speed specified.
5. Set movable flange at nearest keyway of pulley hub
and tighten setscrew to torque specifications.
To align fan and motor pulleys:
1. Loosen fan pulley setscrews.
2. Slide fan pulley along fan shaft. Make angular
alignment by loosening motor from mounting.
3. Tighten fan pulley setscrews and motor mounting
bolts to torque specifications.
4. Recheck belt tension.
Содержание 50LC 07
Страница 9: ...9 COOLING CHARGING CHARTS C150169 Fig 9 Cooling Charging Charts 07 ...
Страница 10: ...10 COOLING CHARGING CHARTS C150172 Fig 10 Cooling Charging Charts 08 ...
Страница 11: ...11 COOLING CHARGING CHARTS C150170 Fig 11 Cooling Charging Charts 09 ...
Страница 12: ...12 COOLING CHARGING CHARTS C150171 Fig 12 Cooling Charging Charts 12 ...
Страница 27: ...27 C150181 Fig 34 50LC 07 Control Wiring Diagram ...
Страница 28: ...28 C150225 Fig 35 50LC 07 RTU Open Control Wiring Diagram ...
Страница 29: ...29 C14095 Fig 36 50LC 07 Power Wiring Diagram 208 230V 460V and 575V Units ...
Страница 30: ...30 C14013 Fig 37 50LC 08 12 Control Wiring Diagram ...
Страница 31: ...31 C14104 Fig 38 50LC 08 12 RTU Open Control Wiring Diagram ...
Страница 32: ...32 C14105 Fig 39 50LC 08 12 Power Wiring Diagram 208 230V Units ...
Страница 33: ...33 C150216 Fig 40 50LC 08 12 Power Wiring Diagram 460V 575V Units ...
Страница 57: ...57 C13683 Fig 62 Typical EconoMi er X Wiring Diagram ...