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44
Fig. 54 —
EconoMi$er IV Wiring
Step 13 —
Check Belt Tension
Measure the belt span length as shown in Fig. 55. Calculate the re
-
quired 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
inch
deflection.
BELT FORCE — DEFLECTION METHOD
Check the belt tension with a spring-force belt force deflection
gauge (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 gauge to the desired tension (see Table 1 in
Fig. 55). 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. 56) and slide the plate towards the fan (to
reduce tension) or away from the fan (to increase tension). 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 gauge that measures tension in belt in units
of lbs force.
Fig. 55 —
V-Belt Force Label
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
Summary of Contents for 50HCQ12
Page 4: ...4 Fig 2 Unit Dimensional Drawing Size 12 Units ...
Page 5: ...5 Fig 2 Unit Dimensional Drawing Size 12 Units cont ...
Page 9: ...9 Fig 6 Roof Curb Details REV 50TM500827 ...
Page 25: ...25 Fig 42 Typical 50HCQ Control Wiring Diagram ...
Page 26: ...26 Fig 43 Typical 50HCQ Power Wiring Diagram 208 230 3 60 unit shown ...
Page 27: ...27 Fig 44 PremierLink Controller Wiring Schematic ...
Page 28: ...28 Fig 45 RTU Open Controller System Wiring Diagram ...