Installation manual

Page 44 IM-487
Adjustment of Supply Fan Thrust Restraints
Thrust restraints are provided when housed double-width fans
are mounted on springs. After the spring mounts have been
adjusted for level operation when the fan is running, check the
thrust restraints. With the fan off, set the adjustment nuts so
the spring is slightly compressed against the angle bolted to
the fan housing frame. When the fan is turned on, the fan will
move back to a level position and the thrust restraint springs
will compress. Refer to Figure 51 on page 44.
1. With the fan off, loosen Jam Nuts "A".
2. Turn Nut "C" until the spring cup and washer contact
thrust restraint angle.
3. Turn Nut "B" until spring is compressed by two turns of
Nut "B".
4. Tighten Jam Nuts "A".
Figure 51. Thrust Restraint Adjustment
Adjustment of Spring Mounts
During operation, all fans should ride level, with the bottom
of the fan base approximately 3/8" (10mm) above the top of
the unit's cross channel. Unhoused single-width "plug" fans
will also ride at this level when at rest.
When not operating, housed double-width fans will ride
lower at the discharge end of the fan base than at the motor
end. When the fan is operating against a static pressure, it
should run level. If not, level the assembly as follows:
(refer to Figure 52)
1. Loosen the 15/16" jam nut above the fan base.
2. Using a large, straight blade screwdriver, turn the 5/8"
leveling screw clockwise to lower the fan base, counter-
clockwise to raise the fan base.
3. When properly adjusted, retighten the jam nut.
.
Figure 52. Fan Spring Mount Adjustment
* This (10mm) can be affected by thrust restraints that are grossly out of
adjustment. This dimension must be rechecked after thrust restraints are
adjusted.
Adjustment of Seismic Restraints
Spring mounted supply air and return air fans may be ordered
with factory installed seismic restraints. The system consists
of four snubbers, one located next to each spring isolator.
These snubbers will allow free movement of the fan assem-
blies during normal operation because normal operation will
not cause fan movements that exceed .25" (6 mm). However,
they will restrain the fan assembly and limit movement to
.25" (6 mm) in any direction if an abnormal condition were
to occur.
The position the fan will assume during normal operation
will be determined by actual job site airflow and static pres-
sure. Therefore, for proper operation, the seismic restraints
must be field adjusted as part of the normal "Check, Test and
Start" procedure. When the fan is operating in a normal man-
ner there should be no contact between the snubber restrainer
N u t " B "
S p r i n g C l i p
W a s h e r
N u t " C "
F a n B u l k h e a d
J a m N u t " A "
J a m N u t " A "
T h r u s t R e s t r a i n t A n g l e
F a n H o u s i n g F r a m e
S e e D e t a i l " A "
D e t a i l " A "
DANGER
Moving machinery hazard.
Can cause severe injury or death.
Lock out and tag out all power before working on the fans.
F a n
B a s e
3 / 8 " ± 1 / 4 "
( 1 0 m m ± 6 m m )
W I T H F A N
R U N N I N G ! *
S p r i n g
M o u n t
A s s e m b l y
C r o s s
C h a n n e l
L e v e l i n g
S c r e w J a m N u t