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V-Belts
Installation Guide
The following sections detail other issues that
could arise during V-belt drive installation:
14. Belt guards
V-belt drive guards ensure cleanliness and safety. Screened,
meshed or grilled guards are preferable because they allow for
air circulation and heat escape.
15. Idlers
Avoid the use of idlers if at all possible. A properly-designed
V-belt drive will not require an idler to deliver fully-rated
horsepower. Idlers put an additional bending stress point on
belts, which reduces their horsepower rating and life. Also,
remember the smaller the idler, the greater the stress and the
shorter a belt’s life; however, if the drive design requires an
idler, observe the following design recommendations.
Inside idler
A V-grooved idler located on the inside of the belts on the slack
side of the drive is preferable to a back side idler. Locate the
idler near the large sheave to avoid reduction of the arc of
contact with the small sheave.
Note that the size of the V-idler pulley should be equal to or
larger (preferably) than the diameter of the small sheave.
Back side idler
A back side idler increases the arc of contact on both sheaves;
however, such an idler also forces a backward bend in the
V-belt, which contributes to unwanted wear such as bottom
cracking and premature failure. If a back side idler is the only
option, follow two guidelines:
1. Make sure the diameter of the flat idler pulley is at least
1.5 times the diameter of the small sheave.
and
2. Locate the back side idler as close as possible to the small
sheave on the slack side.
Kiss idler
Unlike the back side idler, the kiss idler does not penetrate the
belt span and create a back bend. Consequently, the kiss idler
does not contribute to premature failure. The kiss idler can help
control belt vibration and whip on drives subject to shock and
pulsating loads. When using a kiss idler, make sure the diameter
of the flat pulley is at least 1.5 times the diameter of the small
sheave on the slack side.
Driven
Driver
Driver
Driven
Driven
Driver
V-Belts
Installation Guide
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