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Installation and Maintenance 55
Over-tensioning of belts can cause damage to
bearings, shafts, and drive components. Belts should
not squeal at start-up. Belt tension should be
rechecked after 8 hours, 24 hours, and 100 hours of
operation and monthly thereafter. When the belt is in
operation, the tight side of the belt should form a
straight line from sheave with only a slight bow on the
slack side.
Fan Belt Tension
NOTE: FAN BELT TENSION SHOULD BE CHECKED AT
LEAST THREE TIMES DURING THE FIRST DAYS OF
OPERATION, SINCE THERE IS A RAPID DECREASE IN
TENSION UNTIL BELTS SETTLE IN. REFER TO THE
DRIVE STICKER FOR PROPER TENSION.
Figure 46
Typical Drive Belt Label
WARNING
Disconnect electrical power
source and allow all rotating
equipment to stop completely
before inspecting or servicing the
unit. Failure to do so may result in
personal injury or death from elec-
trical shock or moving parts.
Disconnect electrical power prior
to access into a fan or ductwork.
Even when locked out electrically,
fans may cause injury or damage if
the impeller is subject to “wind-
milling.” The impeller should be
secured to physically restrict rota-
tional movement. Failure to secure
impeller can cause severe per-
sonal injury or death.
Figure 47
Fan Sheave Pitch Diameter
Figure 48
Belt Tension Measurement
Table 46
Values for K-Factor (Belt Cross Section Types)
Belt Type
ABCDE3L4L
K Factor
8 13408095 6 6
Belt Type
5L 3V 5V 8V AX BX CX DX
K Factor
6 6 12 25 11 18 54 101