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CAH-SVX01A-EN 47
Determine Fan
Speed
ƽ WARNING
Rotating Components!
During installation, testing,
servicing and troubleshooting of
this product it may be necessary to
measure the speed of rotating
components. Have a qualified or
licensed service individual who has
been properly trained in handling
exposed rotating components,
perform these tasks. Failure to
follow all safety precautions when
exposed to rotating components
could result in death or serious
injury.
Fan speed can be determined using
a strobe-type tachometer, or
revolution counter.
Check unit vibration if the fan speed
is changed more than 5 percent from
the original designed speed, or if
parts such as shafts, fan wheels,
bearings, or other drive components
are replaced. Do not exceed the
maximum fan speed.
Pay particular attention to any
vibration, noise, or overheating of
the motor and fan bearings;
however, note that bearings may run
warm during break in.
Sheave Alignment
Align the fan and motor sheaves
using a straightedge. The
straightedge must be long enough
to span the distance between the
outside edges of the sheaves. When
the sheaves are aligned, the
straightedge will touch both sheaves
at points A through D (see
Figure 48) to confirm the shaft is
parallel. For uneven width sheaves,
place a string in the center groove of
both sheaves and pull tight. Adjust
the sheaves and tighten the sheave
set screws to the proper torque
given in Table 4.
Multibelt Check
Tighten the belts slightly and rotate
the drive several times.
On multiple belt drives, ensure the
force of deflection is approximately
the same on each belt by pushing
each belt in an equal distance at a
point halfway from each sheave (see
Figure 48). If this force is not the
Figure 48. Proper drive alignment
Table 4. Fan and drive compound torque settings (inches)
Screw Size Hex Key Square Head Hex Head Torque (in.-lb.) Torque (ft.-lb.)
1/4 1/8 3/8 7/16 66-90 5.5-7.5
5/16 5/32 1/2 1/2 126-164 10.5-13.7
3/8 3/16 9/16 9/16 228-300 19.0-25.0
7/15 7/32 5/8 5/8 348-450 29.0-37.5
1/2 1/4 3/4 3/4 504-650 42.0-54.2
5/8 5/16 15/16 15/16 1290-1390 107.0-116.0
same for each belt, the motor and
fan shaft are not parallel. Realign as
required. After realignment, tighten
the belts again to the standard belt
tensioning specifications. If the force
is still not the same for all belts, the
belts or sheaves are worn and must
be replaced.