Twin City Fans Using Taperlock Hub & Bushing - ES-106 - Manual

1. Installation instructions for impellers equipped with
Browning malleable iron split taper bushings: (see
Figure 1)
a. Low profile plug fans are furnished with split taper
bushings for mounting the impeller to the shaft.
When properly assembled, the bushings grip the
hub with positive clamping action.
b. Capscrews, when tightened, lock the bushing
in the impeller. Use special plated capscrews
threaded full length furnished by Twin City Fan and
Blower.
c. The bushing is split so that when the locking cap-
screws force the bushing into the tapered bore,
the bushing grips the shaft with a positive clamp-
ing fit. This will withstand vibration and punishing
loads without being loosened.
d. The impeller and bushing assembly is keyed to the
shaft and held in place by compression. This gives
added driving strength. Before assembly, be sure
that the shaft and keyway are clean and smooth.
Check the key size with both the shaft and bush-
ing keyways.
e. To assemble, insert the capscrews through the
clearance holes in the bushing and place the
bushing loosely into the impeller. Do not press or
drive. Start the capscrews by hand, turning them
just enough to engage the threads in the tapped
holes on the impeller. Do not use a wrench at this
time. The bushing should be loose enough in the
impeller to move slightly. Slide the impeller and
bushing assembly onto the shaft, making allow-
ance for endplay of the shaft to prevent rubbing.
Install the key into the keyway. Do not force the
impeller and bushing onto the shaft. If it does not
go on easily, check the shaft, bushing and key
sizes once again.
f. Tighten the capscrews progressively with a
wrench. Do this evenly as in mounting an auto-
mobile wheel.Tighten each capscrew part of a turn
successively until all are tight. These capscrews
force the taper bushing into the hub, which in
turn compresses the bushing onto the shaft. This
makes a positive clamping fit. The torque must not
exceed that shown in Table 1. WARNING: Do
not attempt to pull the bushing flange flush with
the hub end. There should be a clearance that
varies approximately 1/8" to 1/4" with the bushing
size when tightened. (Note: this is not a locating
dimension.)
2. Instructions for removing impeller assembly from the
shaft:
a. Remove all capscrews from the impeller and hub
assembly.
b. Start capscrews into the threaded holes in the
bushing flange.
c. Tighten each bolt successively part of a turn to
force the impeller off the bushing. This forces the
bushing loose from the impeller and releases the
compression so that the entire assembly will slide
from the shaft.
d. Pull the bushing off the shaft. If the assembly has
been in place some time, it may be necessary to
use a wheel puller to remove the bushing. Never
use a wheel puller on the impeller.
DO NOT LUBRICATE
CAPSCREWS, BORE, OR
BUSHING BARREL
Figure 1. Split Taper Bushing with Hub
TM
®
INSTALLATION, OPERATION & MAINTENANCE MANUAL
Fans Using Taperlock Hub & Bushing
ENGINEERING SUPPLEMENT
ES-106
Issue Date: 4-27-06
Rev. Date: NEW
BUSHING
DIAMETER
LENGTH TORQUE
NO. (IN.) FT. LBS.
H 1 ⁄ 4 -20 1 1 ⁄ 4 7 1 ⁄ 2
P-1 5 ⁄
16
-18 1 1 ⁄
2
13
P-2 5 ⁄
16
-18 1 3 ⁄
4
13
Q-1 3 ⁄ 8 -16 1 1 ⁄ 4 29
Q-2 3 ⁄
8
-16 2 1 ⁄
2
24
R-1 3 ⁄ 8 -16 1 3 ⁄ 4 29
R-2 3 ⁄
8
-16 3 24
Table 1. Capscrew Torque Values - Split Taper Bushings