Page 12 - Goodyear2011PTMaintenanceManual

V-Belt
INSTALLATION GUIDE
12
The following sections detail other issues that could arise during
V-belt drive installation.
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.
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 a belt’s horsepower rating and its 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.
14
15
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 fat 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 fat pulley is at least 1.5 times the diameter of the small
sheave on the slack side.