Bryant Legacy 549J 12 Series, Руководство по установке

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Step 13 — Check Belt Tension
Measure the belt span length as shown in Fig. 54. Calculate the
required deflection by multiplying the belt span length by
1
/
64
.
For example, if the belt span length is 32 inches:
32 x
1
/
64
=
1
/
2
-in. deflection.
BELT FORCE — DEFLECTION METHOD
Check the belt tension with a spring-force belt force deflection
gage (available from drive belt manufacturer).
1. Place a straightedge along the belt between the two pul -
leys. Measure the distance between the motor shaft and the
blower shaft.
2. Set the tension gage to the desired tension (see Table 1 in
Fig. 54). Place the large O-ring at that point.
3. Press the tension checker downward on the belt until the
large O-ring is at the bottom of the straightedge.
4. Adjust the belt tension as needed.
Adjust belt tension by loosing the motor mounting plate front
bolts and rear bolt (see Fig. 55) and slide the plate towards the
fan (to reduce tension) or away from the fan (to increase ten -
sion). Ensure the blower shaft and motor shaft are parallel to
each other (pulleys aligned). Tighten all bolts securely when
finished.
BELT TENSION METHOD
Requires belt tension gage that measures tension in belt in units
of lbs force.
Fig. 54 — V-Belt Force Label
Fig. 55 — Belt Drive Motor Mounting
Pre-Start and Start-Up
This completes the mechanical installation of the unit. Refer to
the unit’s Service Manual for detailed Pre-Start and Start-Up
instructions. Download the latest versions from HVAC Part -
ners (www.hvacpartners.com).
Table 1
Table 2
BELT
CROSS
SECTION
SMALLEST
SHEAVE
DIAMETER
BELT DEFLECTION FORCE (LBS)
UNNOTCHED
BELTS
NOTCHED BELTS
USED NEW USED NEW
A, AX
3.0-3.6 3.7 5.5 4.1 6.1
3.8-4.8 4.5 6.8 5.0 7.4
5.0-7.0 5.4 8.0 5.7 8.4
B, BX
3.4-4.2 — — 4.9 7.2
4.4-5.6 5.3 7.9 7.1 10.5
5.8-8.6 6.3 9.4 8.5 12.6
BELT CONDITION TENSION FORCE IN BELT (LBS)
New 100
Used 80
TORQUE ALL SHEAVE SET SCREWS TO 110-130 in. lbs
SET
SCREW
SET
SCREW
STRAIGHT
EDGE
BELT SPAN
BELT DEFLECTION FORCE - SEE TABLE 1
DEFLECTION = BELT SPAN
64
BLOWER PULLEY
V-BELT
MOTOR
PULLEY
MOTOR
MOTOR MOUNTING
PLATE
MOUNTING
BOLTS (4)