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sheave to determine the diameter. If diameter markings are unreadable,
measure the sheave diameter at the bottom of the sheave grooves.
New belts (operating less than 8 hours) should be tensioned to the maxi-
mum value. Tension after this period should use no less than the minimum
value. If the belt span was measured in inches, then use the pounds of
force values. If the belt span was measured in centimeters, then use the
kilograms of force values. If specic tensioning instructions are provided
with your tensioning tool, those instructions should be used instead.
Sheave Alignment
Always shut off electrical power to the tower fan motor prior to
performing any inspections that may involve physical contact with
the mechanical or electrical equipment in or on the tower. Lock out
and tag out any electrical switches to prevent others from turning
the power back on. Service personnel must wear proper personal
protective clothing and equipment.
• Themotorsheaveistobepositionedascloseaspossibletothemotor
in order to minimize torque on the motor bushings.
• Themotorandfansheavesmayhavegroovesthatarenotused.The
bottom surface of the motor and fan sheaves must be aligned within
1
⁄8" of each other and level within
1
⁄2° (
1
⁄8" in 12") in order to not adversely
affect belt and sheave life.
• Alignmentcanbeachievedbyplacingastraightedgeacrossthetop
of the sheaves making sure that it is level and measuring down to the
bottom surface of both sheaves at four points. See photo.
• Thenumberofgroovesonthemotorandfansheavesmaynotmatch
each other, or the number of grooves on the belt. Always install the
belts on the highest grooves on the fan sheave. Doing so will reduce
the force on the fan shaft bearings, thus increasing their life.
Maintenance
Warning
Motor Sheave
diameter
Used V-Belt
minimum
New V-Belt
maximum
3.4" - 4.2" 4.9 lb 7.2 lb
85cm - 105cm 2.2 kg 3.3 kg
4.4" - 5.6" 7.1 lb 10.5 lb
106cm - 140cm 3.2 kg 4.8 kg
5.8" - 8.6" 8.5 lb 12.6 l
141cm - 220 cm 3.9 kg 5.7 kg