18
Tension Measurement Procedure
1. Measure the belt span (see Fig. 23).
2. Position bottom of the large O-ring on the span scale at
the measured belt span.
3. Set the small O-ring on the deflection force scale to zero.
4. Place the tension checker squarely on one belt at the cen-
ter of the belt span. Apply a force on the plunger and per-
pendicular to the belt span until the bottom of the large O-
ring is even with the top of the adjacent (next) belt or with
the bottom of a straight edge laid across the outside diam-
eters of the v-belt sheaves.
5. Remove the tension checker and read the force applied
from the bottom of the small O-ring on the deflection
force scale.
6. Compare the force you have applied with the values giv-
en in Table 5. The force should be between the “Used
Belt” and “New Belt” values shown. The maximum val-
ue is shown for “New Belt” and new belts should be
tensioned at this value to allow for expected tension loss.
“New Belt” tensions should be used at initial installation
and after job start or 1 to 3 minutes of operation. Used
belts should be maintained at the value as indicated in the
chart. “Used Belt” tensions should be used for the 8-hour
and subsequent checks. If the belt span was measured in
centimeters, then use the kilograms of force values for
comparison.
NOTE: The ratio of deflection to belt span is 1:64 in either
unit of measurement.
Whenever possible, jog start for a few revolutions or prefer-
ably run drive for approximately 1 to 3 minutes and then re-
tension in accordance with Steps 1-6. Running the drive for a
few revolutions or minutes will help seat the belt(s) in the
groove(s). This relatively early re-tensioning may reduce or
minimize the amount of re-tensioning required in the first 24
hours of drive service. Record information on the label
(Fig. 24) found on the door of the fan section.
Table 5 — Fan Belt Tension Data
SHEAVE DIAMETER (in.)
DEFLECTION FORCE (lb)
BELT STYLE
SMALLEST
SHEAVE DIAMETER
RANGE
RPM RANGE
BELT DEFLECTION FORCE
SUPER GRIPBELTS AND UNNOTCHED
GRIPBANDS
GRIPNOTCH BELTS AND NOTCHED
GRIPBANDS
USED BELT
NEW BELT
USED BELT
NEW BELT
A, AX
3.0 - 3.6
1000-2500
2501-4000
3.7
2.8
5.5
4.2
4.1
3.4
6.1
5.0
3.8 - 4.8
1000-2500
2501-4000
4.5
3.8
6.8
5.7
5.0
4.3
7.4
6.4
5.0 - 7.0
1000-2500
2501-4000
5.4
4.7
8.0
7.0
5.7
5.1
8.4
7.6
B, BX
3.4 - 4.2
860-2500
2501-4000
—
—
—
—
4.9
4.2
7.2
6.2
4.4 - 5.6
860-2500
2501-4000
5.3
4.5
7.9
6.7
7.1
6.1
10.5
9.1
5.8 - 8.6
860-2500
2501-4000
6.3
6.0
9.4
8.9
8.5
7.3
12.6
10.9
C, CX
7.0 - 9.0
500-1740
1741-3000
11.5
9.4
17.0
13.8
14.7
11.9
21.8
17.5
9.5 - 16.0
500-1740
1741-3000
14.1
12.5
21.0
18.5
15.9
14.6
23.5
21.6
D
12.0 - 16.0
200-850
851-1500
24.9
21.2
37.0
31.3
—
—
—
—
18.0 - 20.0
200-850
851-1500
30.4
25.6
45.2
38.0
—
—
—
—
3V, 3VX
2.2 - 2.4
1000-2500
2501-4000
—
—
—
—
3.3
2.9
4.9
4.3
2.65 - 3.65
1000-2500
2501-4000
3.6
3.0
5.1
4.4
4.2
3.8
6.2
5.6
4.12 - 6.90
1000-2500
2501-4000
4.9
4.4
7.3
6.6
5.3
4.9
7.9
7.3
5V, 5VX
4.4 - 6.7
500-1749
1750-3000
3001-4000
—
—
—
—
—
—
10.2
8.8
5.6
15.2
13.2
8.5
7.1 - 10.9
500-1749
1750-3000
3001-4000
12.7
11.2
18.9
16.7
14.8
13.7
22.1
20.1
11.8 - 16.0
500-1749
1750-3000
3001-4000
15.5
14.6
23.4
21.8
17.1
16.8
25.5
25.0
8V
12.5 - 17.0
200-850
851-1500
33.0
26.8
49.3
39.9
—
—
—
—
18.0 - 22.4
200-850
851-1500
39.6
35.3
59.2
52.7
—
—
—
—