COOK H-Series - Manual (Page 6)

6
Changing Shaft Speed
All belt driven H-Series fans with motors up to and includ-
ing 5HP are equipped with variable pitch pulleys. To
change the fan speed, perform the following:
a. Loosen setscrew on driver (motor) pulley and remove
key, if equipped.
b. 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.
c. After adjustment, inspect for proper belt tension.
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 main-
tained.
Pulley and Belt Replacement
a. Clean the motor and fan shafts.
b. Loosen the motor plate mounting bolts to relieve the
belt tension. Remove the belt.
c. 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.
Pulley and Belt Replacement continued
d. Clean the bores of the pulleys and place a light coat of
oil on the bores.
e. Remove grease, rust and burrs from the shaft.
f. 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.
g. After the pulleys have been correctly placed back onto
their shafts, tighten the pulley setscrews.
h. Install the belts on the pulleys. Align and adjust the
belts to the proper tension as described in Belt and Pul-
ley Installation, page 2.
Bearing Replacement
The fan bearings are pillow block ball bearings.
a. Remove the top cap or hood as necessary to gain
access to the fan.
b. Loosen the motor plate mounting bolts and remove the
drive belts.
c. Remove the propeller from the shaft.
d. Remove the four (4) bearing hold-down bolts and then
remove the shaft, bearings, and driven sheave from the
unit as an assembly.
e. Measure and record the location of the bearings and
sheave on the shaft. This will aid the reassembly.
f. Remove the anti-corrosion coating from the shaft with
a suitable degreaser and then remove the pulley from
the shaft.
g. Remove the bearing from the shaft using a bearing
puller.
h. Install the pulley in the correct location on the shaft
Secure the bearing hold-down bolts, but do not fully
tighten.
i. Align the setscrews on the bearings and tighten one
setscrew on each bearing.
j. Rotate the shaft to allow the bearing outer rings to find
their center of free movement.
k. Install the propeller on the shaft and adjust the bearing
position to center the propeller in the opening.
l. Tighten the hold-down bolts to the proper torque. Refer
to Torque Chart, page 4.
m. Turn the shaft by hand. Resistance should be the same
as it was before the hold-down bolts were fully tight-
ened.
n. Tighten the bearing setscrews to the specified torque.
o. Install the pulley and adjust the belt tension.
p. Reassemble the fan.
After 24 hours of continuous operation, tighten the set-
screws to the appropriate torque. This assures the full lock-
ing of the inner race to the shaft. Ensure the socket key or
driver is in good condition with no rounded corners. The
key should be fully engaged in the setscrew and held
squarely to prevent the rounding out of the setscrew socket
when applying maximum torque.
Propeller and Shaft Replacement Precautions
• If the shaft is dropped and bent, it may cause unbal-
anced operation of the fan.
• When handling the propeller separately from the shaft,
place a support through the hub for lifting, making sure
not to injure the finished bore of the propeller.
• Never allow the propeller to rest its entire weight on the
blades. The propeller and shaft can be lifted by slings
around the shaft on each side of the propeller so the
propeller is supported by its hub.
• If using a chain to lift the propeller, make sure there is
sufficient padding on the shaft and propeller. This pre-
vents the scoring of the shaft or injury to the propeller.
The chain or cable should be spread with timbers, or
braced by some other method to prevent damage to
the propeller side plates.
Maximum RPM
HXEL, HXSL, HXFL
Size
Maximum
RPM
HXEM, HXSM, HXFM
Size
Maximum
RPM
20 1276 20 1462
24 1126 24 1400
30 932 30 1184
36 720 36 864
42 610 42 718
48 516 48 598
54 478 54 522
60 450 60 539
Maximum RPM
HEE
Size Maximum
RPM
HES
Size Maximum
RPM
HEF
Size Maximum
RPM
HER
Size
Maximum
RPM
24 1675 24 1630 24 1635 24 1635
30 1295 30 1330 30 1330 30 1325
36 1125 36 1165 36 1160 36 1145
42 880 42 885 42 880 42 920
48 822 48 830 48 816 48 818
54 776 54 742 54 735 54 748
60 636 60 642 60 634 60 642