Misalignment may be due to
wear of bearings and in extreme cases of failures it may be difficult to determine
whether a bearing or a gear failed first. In case of bearing failures, when
lubrication was at fault, either oil did not get to the bearing. Or the proper
oil was not used. Where a common oil is used for bearings and gearing,
the viscosity of the oil is generally
a compromise since the bearings operate best with a lower
viscosity oil than is dictated
for the gear sets. Therefore, when bearing trouble is encountered, thought might
be given to use of a somewhat lower viscosity lubricant.
Malfunctioning of flexible couplings
may also contribute to trouble with gear sets. Such couplings are often used to
connect reduction gears with a different piece of apparatus. These couplings may not only break but
also become jammed, so that they
are no longer flexible; thus the
gear shaft will be thrown out of line. Another possible source
of trouble might be a break in a gear case or supports which would permit a
shaft carrying gears to be misaligned.
