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particular span. Then, one can adjust the belt tension until
the actual deflection force equals the target.
Run the drive briefly to properly seat the belt. At least one
sheave should rotate freely during the tensioning procedure.
Measure the span length (see illustration).
Mark the center of span. At the center point, use a tension tester
and apply a force perpendicular to the span large enough to
deflect the belt 1/64 inch for every inch of span length
(example: a 100 inch span requires a deflection of 100/64 inch
or 1_⁄{| inches).
Compare the actual deflection force with the values in
Table 16 below.
A force below the target value indicates under-tension; a force
above the target indicates over-tension.
Force
Span Length
Deflection
.015 in. per
in. of span
Poly-V
®
Belts
Installation Guide
Tensioning Methods
Choose one of two tensioning methods for
Poly-V® belts:
TensionRite® Belt Frequency Meter
Using advanced optical technology, our TensionRite® Belt
Frequency Meter provides a simple, repeatable and reliable
method for tensioning belts. It displays the natural vibration
frequency of the belt strand so you can closely monitor belt
tension. The device works with all industrial transmission belts,
including V-belts, synchronous belts, banded belts and Poly-V®
belts and calculates the corresponding belt tension in either
English or SI units.
Deflection Principle
Plunger-type gauges utilize the Deflection Principle to check the
tension of a belt drive.
The gauge deflects the center of the belt span and the force of
this deflection is compared to a target deflection force for the
Banded Belts
Installation Guide
Table 16 Belt Deflection Force
Belt Cross
Section
Small Sheave
Diameter Range
Force “F”
(lb. per rib)
J
1.32-1.67
0.4
J
1.77-2.20
0.5
J
2.36-2.95
0.6
L
2.95-3.74
1.7
L
3.94-4.92
2.1
L
5.20-6.69
2.5
M
7.09-8.82
6.4
M
9.29-11.81
7.7
M
12.40-15.75
8.8
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