5
FCE/FCRU IO&M
B51150-003
Belt and Pulley Installation
Belt tension is determined by the sound of the belts when
the fan is first started. The belts will produce a loud squeal,
which dissipates after the fan is operating at full capacity.
If belt tension is too tight or too loose, lost efficiency and
damage may occur.
Do not change the pulley pitch diameter to change ten-
sion. The change will result in a different fan speed.
1. Loosen motor plate adjustment bolts and slide motor
plate so that belts easily slip into the grooves on the
pulleys. Never pry, roll, or force the belts over the rim
of the pulley.
2. Slide 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 1
.
3. Lock the motor plate adjustment bolts in place.
4. Ensure pulleys are properly aligned. Refer to
Figure 2
.
Tolerance
Center
Distance
Max.
Gap
Up through
12”
1/16”
12” up
through 48” 1/8”
Over 48”
1/4”
OFFSET
ANGULAR
OFFSET/ANGULAR
A
W
X
Y
Z
B
CENTER
DISTANCE
(CD)
GAP
GAP
Pulley Alignment
Pulley alignment is adjusted by
loosening the motor pulley set-
screw and by moving the motor pul-
ley on the motor shaft.
Figure 2
indicates where to mea-
sure the allowable gap for the drive
alignment tolerance. All contact
points (indicated by WXYZ) are to
have a cap less than the tolerance
shown in the table. When the pul-
leys are not the same width, the al-
low-able gap must be adjusted by
half of the difference in width.
Figure 3
illustrates using a
carpenter’s square to adjust the position of the motor pul-
ley until the belt
Figure 3
is parallel to the longer leg of the
square.
Motor Services
Should the motor prove defective within a one-year pe-
riod, contact your local Loren Cook representative or your
nearest authorized electric motor service representative.
Changing Shaft Speed
All belt driven ventilators (5HP or less) are equipped with
variable pitch pulleys. To change fan speed, perform the
following:
1. Loosen setscrew on driver (motor) pulley and remove
key, if equipped.
2. Turn the pulley rim to open or close the groove facing.
If the pulley has multiple grooves, all must be adjusted
to the same width.
3. After adjustment, inspect for proper belt tension.
Size
Maximum RPM
Standard
HP Only
120
4500
4500
150
3600
4300
180
2900
3600
245
2200
2700
270
2000
2400
300
1800
2200
330
1650
2000
365
1500
1800
402
1350
1650
Speed Reduction
Open the pulley in order that the belt rides deeper in the
groove (smaller pitch diameter).
Speed Increase
Close the pulley in order that the belt rides higher in
the groove (larger pitch diameter). Ensure that the RPM
limits of the fan and the horsepower limits of the motor are
maintained.
Replacing Pulleys and Belts
1. Clean the motor and fan shafts.
2. Loosen the motor plate mounting bolts to relieve the
belt tension. Remove the belt.
3. Loosen the pulley setscrews and remove the pulleys
from the shaft.
If excessive force is required to remove
the pulleys, a three-jaw puller can be used. This tool,
however, can easily warp a pulley. If the puller is used,
inspect the trueness of the pulley after it is removed
from the shaft. The pulley will need replacement if it is
more than 0.020 inch out of true.
4. Clean the bores of the pulleys and place a light coat of
oil on the bores.
5. Remove grease, rust and burrs from the shaft.
6. Place fan pulley on the fan shaft and the motor pulley
on the motor shaft. Damage to the pulleys can occur
when excessive force is used in placing the pulleys on
their respective shafts.
7. After the pulleys have been correctly placed back onto
their shafts, tighten the pulley setscrews.
8. Install the belts on the pulleys. Align and adjust the
belts to the proper tension as described in
Belt and
Pulley Installation
.
1 foot
1/4 inch
Figure 1
Figure 2
