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Fig. 10
Fig. 11
Return Idlers
Return idlers, being flat, provide no self-aligning influence as
in the tilted troughing idlers. However, by shifting their axis
with respect to the path of the belt, the return roll can be used
to provide a constant corrective effect in one direction. As in
the troughing rolls, the end of the roll toward which the belt
is shifting should be moved longitudinally in the direction of
return belt travel to provide correction.
Self-aligning return rolls also should be used. These rolls are
pivoted about a central pin.
Pivoting of the roll about this pin
results from an off-center belt and the idler roll axis thus
becomes shifted, with respect to the path of the belt, in a
corrective direction (Fig. 10).
Typical Self-Aligning Return Idler
Some return idlers are made with two
rolls forming a 10-degree to 20-degree
V-trough, which is effective in helping to
train the return run. The V-return idlers
are only recommended for fabric belts
wider than 54”. The most important
criteria for belt training is idler contact in
the center. If the belt has taken a set on
the trough side and V-return idlers are
being used, the center of the belt is not
able to make contact with the center of
the V-return idlers. A hold-down roller on
the return side will help in training the
belt, as it forces the belt to lay flat on the
following idlers.
Rubber-segmented disk return idlers
(Fig. 11) are used for cleaning the belt
and help in belt training.
When one of
the discs on the edges falls off, the belt
edges tend to get caught, forcing the belt
to run one way and become a belt de-
trainer. Minimum of 8” of belt contact is
recommended for disc return idlers.
Rubber Disk Return Idler
10
Installation, Maintenance & Troubleshooting Guide
Installation