Different problems may
arise in connection with flushing gear cases. First the used oil should be
removed from the case as completely as possible so that
contaminants are also removed and none of the Oxidized
oil remains to act as a catalyst for the fresh oil. In
so doing, if a volatile solvent is used, this should also be removed
completely. Very little of a solvent is required to reduce the viscosity of
gear oil, and naturally this is undesirable. Further the gears should not
be left without a coating of oil for even a short
period because rusting will take place under such
conditions. Also the gears should not be operated
without a coating of oil, even though there is no load.
Troubles have been encountered when gear cases were washed out with chlorinated
solvents.
After fresh oil was added, corrosion developed because some of the
solvent was trapped in the case. The best correction for this problem is not to
use such a solvent. In fact the safest course in flushing gear cases is to use
prepared flushing oil.
