（1）The internal structure of the reducer is not standardized : In the structure of the reducer, because the cover plate above the inspection hole is easily deformed after tightening the screw cause it is too thin,, causing gaps and oil leakage. The casting is not annealed during the production process. The oil leakage occurs due to the deformation and voids. It may also because there is no oil return groove on the box, when too much oil accumulates on the end cover of the reducer box and the structural joint surface, the pressure difference constitutes oil eak to outside from the joint gap.
（2）Oil leakage in the box causes environmental pollution : The factors that caused oil leakage in the box include damage to the oil seal, damaged gasket, loose oil plug or damaged oil mark, or there may be too much oil, high oil level or the blistering caused by multiple cold starts, causing a large amount of oil leakage at the vent plug and severe environmental pollution.
（3）Excessive oil temperature causes equipment damage : During the operation of the reducer, the temperature of the reducer rises rapidly due to the lack of lubricating oil or the overloading of the equipment, which causes a partial damage to the relevant parts of the reducer. Because the internal stress of some equipment is not eliminated, the precision of the reducer will decrease due to thermal deformation, and some equipment will be damaged due to the decrease of material strength under high temperature conditions. In addition, some reducers with insensitive operations and severe power loss during operation may cause the transmission parts to be jammed when objects invade, appearing uneven operation or abnormal oscillation.
（4）Oscillation and noise cause environmental pollution : After the reducer is started, the gear and bearing are worn out or the transmission device is not installed well, so the machine has obvious shaking. For reasons such as bearing damage, gear wear, gear damage, or jamming, the machine will make out loud and long-lasting harsh sound. The occurrence of these problems will cause severe noise pollution.
（5）Bad gears cause tooth surface wear: Because of the harsh operating environment of the reducer, oil film is hard to stay between the meshing surfaces, resulting in pitting or conflicting wear, deformation, etc on the gear surface, bearing chamber, and outer gear shaft surface.