COOK IMH - Manual (Page 3)

3
Wheel-to-Inlet Clearance
The correct wheel-to-inlet clearance is critical to proper
fan performance. This clearance should be verified before
initial start-up since rough handling during shipment could
cause a shift in fan components. Refer to wheel/inlet draw-
ing below for correct clearance.
Adjust the overlap by loosening the wheel hub and mov-
ing the wheel along the shaft to obtain the correct value.
Wiring Installation
All wiring should be in accordance with local ordinances
and the National Electrical Code, NFPA 70. Ensure the
power supply (voltage, frequency, and current carrying
capacity of wires) is in accordance with the motor name-
plate.
Lock off all power sources before unit is wired to
power source.
Leave enough slack in the wiring to allow for motor
movement when adjusting belt tension. Some fractional
motors have to be removed in order to make the connec-
tion with the terminal box at the end of the motor. To
remove motor, remove bolts securing motor base to power
assembly. Do not remove motor mounting bolts.
Follow the wiring diagram in the disconnect switch
and the wiring diagram provided with the motor. Cor-
rectly label the circuit on the main power box and
Correct
Incorrect
Discharge Duct Turns
MIN 3
DIA
Wheel-to-Inlet Clearance and Overlap
Size
MH, MHBM MHR MHA
Wheel to Inlet
Ring Clearance
Wheel to Inlet
Ring Overlap
Min. Max. Min. Max.
70 3/16 5/16 1/8 1/4
90 3/16 5/16 1/8 1/4
110 3/16 5/16 3/16 5/16
130 3/16 5/16 1/4 3/8
150 3/16 5/16 1/4 3/8
170 3/16 5/16 5/16 7/16
190 3/16 5/16 3/8 1/2
210 5/16 7/16 7/16 9/16
230 5/16 7/16 7/16 9/16
260 5/16 7/16 1/2 5/8
290 5/16 7/16 5/8 3/4
WHEEL TO INLET
CLEARANCE
MH, MHB, MHR
WHEEL TO INLET
OVERLAP
MHA
always identify a closed switch to promote safety (i.e.,
red tape over a closed switch).
Wheel Rotation
Test the fan to ensure the rotation of the wheel is the
same as indicated by the arrow marked Rotation.
115 and 230 Single Phase Motors
Fan wheel rotation is set correctly at the factory. Chang-
ing the rotation of this type of motor should only be
attempted by a qualified electrician.
208, 230, and 460, 3 Phase Motors
These motors are electrically reversible by switching two
of the supply leads. For this reason, the rotation of the fan
cannot be restricted to one direction at the factory. See
Wiring Diagrams on page 4 for specific information on
reversing wheel direction.
Do not allow the fan to run in the wrong direction. This
will overheat the motor and cause serious damage. For
3-phase motors, if the fan is running in the wrong
direction, check the control switch. It is possible to
interchange two leads at this location so that the fan is
operating in the correct direction.
Belt and Pulley Installation
Belt tension is determined by the sound the belts make
when the fan is first started. Belts will produce a loud
squeal which dissipates after the fan is operating at full
capacity. If the belt tension is too tight or too loose, lost effi-
ciency and possible damage can occur.
Do not change the pulley pitch diameter to change ten-
sion. This will result in a different fan speed than desired.
a. Loosen motor plate adjustment nuts and move motor
plate in order that the belts can easily slip into the
grooves on the pulleys. Never pry, roll, or force the
belts over the rim of the pulley.
b. Adjust the motor plate until proper tension is reached.
For proper tension, a deflection of approximately 1/4”
per foot of center distance should be obtained by
firmly pressing the belt. Refer to figure 3.
c. Lock the motor plate adjustment nuts in place.
d. Ensure pulleys are properly aligned. Refer to Figure 4.
Personal Safety
Disconnect switches are recommended. Place the
disconnect switch near the fan in order that the
power can be swiftly cut off in case of an
emergency, and in order that maintenance
personnel are provided complete control of the
power source.
1 foot
1/4 inch
Figure 3