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Supreme Exhaust Fan Service (cont.)
To Replace Fan Wheel Bearings
CAUTION! MAKE SURE THE FAN IS TURNED “OFF” AT THE DISCONNECT SWITCH.
Loosen the wing nuts, open the motor cover and install the cover support arm. Remove the “V” belt (see “How To Replace
Belt”). Remove the driven pulley (See “Driven Pulley”). Loosen the set screws in both bearing collars. Using fine emery
cloth, sand the upper part of the blower shaft to remove any oxidation, rust or burrs. Lift the top locking collar off the shaft.
Make sure to remove the burr that may have been caused by the locking collar set screw. Loosen and remove the two
bolts, nuts and washers that secure the top bearing to the motor frame bearing plate. Slide the bearing up off the blower
shaft. Repeat the complete process to remove the bottom bearing. When the bottom bearing is released, the blower wheel
will drop slightly and rest on top of the intake cone. To install new bearings, slip the bottom bearing down over the shaft.
Raise the blower wheel and shaft and temporarily lay a board across the intake cone to rest the blower wheel on, using the
discharge opening of the fan for access. Install the two bearing bolts, washers and nuts through the bearing and mounting
plate and loosely tighten. Slip the locking collar down over the shaft, leaving loose at this time. Slip the top bearing down
over the shaft. Install the two bearing bolts, washer and nuts through to the bearing and mounting plate, leaving loose at
this time. Slip the top bearing locking collar down over the shaft, leaving loose. Remove the board supporting the blower
wheel. Lower the wheel and shaft until the lower edge of the wheel intake is just above the intake cone (1/16” to 1/8”
clearance). Tighten both sets of bearing bolts securely and recheck the wheel to intake clearances. If clearance is correct,
firmly tighten both bearing locking collar set screws. Manually spin the wheel (through the discharge opening) to verify
proper clearance.
Re-install the blower pulley (see “Driven Pulley), making sure that the pulleys are properly aligned (see “Pulley Alignment”).
Re-install and re-adjust the “V” belt (see “How To Replace Belt” and “How To Adjust Belt Tension”). Turn fan “ON” to
confirm that all is in proper working order. Turn fan “OFF”, replace the motor cover support arm, lower and secure the
motor cover and turn the fan “ON”.
To Replace the Blower Wheel
CAUTION! TURN FAN “OFF" AT THE DISCONNECT SWITCH.
Rotate and open the wheel access cam latch. Lift up the motor frame assembly and install the security pin to hold the
assembly open. Measure and note the distance of the bottom of the wheel hub to the bottom of the shaft for repositioning
the new wheel on the shaft. Loosen the set screws in the hub of the wheel securing the wheel to the shaft. Using fine
emery cloth, sand the lower part of the shaft to remove any accumulation of debris, rust, oxidation or burrs. Using an
appropriate puller, attach the puller jaws to the groove in the blower wheel hub and slowly tighten the forcing screw, draw-
ing the blower wheel from the shaft. Use caution not to lose the shaft key. Before installing the new wheel, use fine emery
cloth to clean the shaft. Remove any burrs that might be present from the previous set screws. To facilitate installation,
lubricate the shaft with WD-40. Slip the new blower wheel onto the shaft and align the keyway, making sure that the wheel
is at the same location as the old wheel (from the measurement previously taken). Slip the key into keyway and lightly
tighten the set screw. Remove the security pin, lower the motor frame assembly and fasten the access cam latch. Double
check the wheel clearance from the intake cone-1/16” to 1/8” clearance, using the fan discharge opening for access.
Manually spin the wheel to verify clearance all around the wheel. Open the cam latch, lift the motor frame assembly and
install the security pin. Make any further adjustments if required. Firmly tighten the set screws in the wheel collar. Remove
the security pin, lower the motor frame assembly and fasten the cam latch. Manually spin the wheel again to verify clear-
ance. Turn the disconnect switch “ON” to verify correct fan operation.
To Replace the Blower Wheel Shaft
See “How To Replace Fan Wheel Bearings” and “How To Replace Blower Wheel”.
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