COOK Duct Blower - Manual (Page 5)

5
Changing Shaft Speed
All belt driven Propeller Wall fans with motors up to and
including 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.
Replacing Pulleys and Belts
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, how-
ever, 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.
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
If you have a model DB or TDB, the fan bearings are per-
manently sealed and will not require replacement.
If you have a model SDB or DBX, the fan bearings are pil-
low block ball bearings. Follow the instructions below for
replacement.
a. Loosen screws on bearing cover.
b. Push bearing cover toward the wheel. As the bearing
cover moves toward the wheel it will slide down to
reveal the bearings and shaft.
c. Remove the old bearing.
d. Remove any burrs from the shaft by sanding.
e. Slide new bearings onto the shaft to the desired loca-
tion and loosely mount bearings onto the bearing sup-
port. Bearing bolts and setscrews should be loose
enough to allow shaft positioning.
f. Correctly position the wheel and tighten the bearing
bolts securely to the bearing support.
g. Align setscrews bearing to bearing and secure tightly
to the shaft. Do not tighten both pairs of setscrews
before securing bearing mounting bolts. This may dam-
age the shaft.
h. Inspect the wheel position again. If necessary, readjust
by loosening the bearing bolts and setscrews and
repeat from step e.
Wheel Replacement—SDB
a. Drill two holes approximately centered between the
shaft and the edge of the hub OD with the following
dimensions.
• 1/4” diameter
• 3/8” to 1/2” deep
• 180° apart in face of hub
b. Tap 1/4” holes to 5/16” thread with the 5/16” hole tap.
Do not drill or tap any larger than recommended.
c. Screw the puller arms into the tapped holes full depth
of threads (3/8” to 1/2” approximately). Align center of
puller with center of shaft. Make certain all setscrews in
hub (normally a quantity of two) are fully removed.
Work puller slowly to back wheel off the shaft.
Recommended Puller
Lisle No. 45000 Steering Wheel Puller. This puller is avail-
able at most automotive parts retail outlets.
Above - Drilled hole placement.
Right - Wheel puller.
Maximum RPM
DB
Size
Maximum
RPM
DBX
Size
Maximum
RPM
8 1494 8 1494
9 1594 9 1594
10 1382 10 1382
13 1094 13 1094
15 973 15 973
18 906 18 906
Maximum RPM
SDB
Size
Maximum
RPM
TDB
Size
Maximum
RPM
100 2795 9 1469
120 2486 10 1382
135 2281 13 1094
150 2088 15 1030
180 1727 18 907
210 1399
245 1284