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Conveyor
Belt
Side Guide
Rollers
Fig. 12
Automatic
Aligning Devices
Self-aligning conveyor and return idlers
have already been described. Center
pivoted return idlers are sometimes
connected in groups of two or three to
operate together and are actuated by
an external mechanism that takes its
indication from the belt position. They
have a very strong influence in centering
the return belt as it approaches the tail
pulley.
A snub pulley also can be arranged to
provide the same strong self-aligning
influence; however, in place of a center
pivot (as in return rolls), it is usually
pivoted at one end of its shaft. The other
end is shifted by mechanical, electrical or
hydraulic means as indication is received
from the belt position.
Assuring Effectiveness
of Training Rolls
Normally, extra pressure is desired on
self-aligning idlers, and in some cases,
on standard idlers where strong training
influence is required. One way to achieve
this is to raise such idlers above the line
of adjacent idlers. Idlers or bend pulleys
on convex curves along the return run
have extra pressure due to a component
of the belt tension, and are therefore
effective training locations. However,
carrying side self-aligners should never
be located on a convex curve, since
their elevated position can promote idler
juncture failure.
Side Guide Rollers
Guides of this type are not
recommended for use in making belts
run straight. They can be used to assist
in training the belt initially to prevent
it from running off the pulleys and
damaging itself against the structure
of the conveyor system. They also
can be used to afford the same sort of
protection to the belt as an emergency
measure, provided they do not touch the
belt edge when it is running normally. If
they bear on the belt continually, even
though free to roll, they tend to wear off
the belt edge and eventually cause ply
separation along the edge. Side guide
rollers should not be located so that they
bear against the belt edge once the belt
is actually on the pulley.
At this point,
no edge pressure can move the belt
laterally (Fig. 12).
11
Installation, Maintenance & Troubleshooting Guide
Installation