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Analysis And Solution Of Oil-Leakage On Gear Speed Reducer
Aug 30, 2018

Cause analysis

     1. Pressure difference between the inside and outside of the reducer: during the operation of the reducer, friction heating of the moving pair and the influence of ambient temperature increase the temperature of the reducer. If there is no blockage of the air hole or the air hole, the pressure inside the reducer will gradually increase. The higher the temperature inside the reducer, the greater the pressure difference with the outside, and the lubricating oil will be affected by the pressure difference. Leaking from the gap.

      2. The reducer structure design is unreasonable.

       1) Inspection hole cover plate is too thin, after tightening bolts easy to produce deformation, so that the joint surface uneven, leakage from the contact gap;

        2) In the manufacturing process of the reducer, the castings will inevitably deform without annealing or aging treatment and internal stress is not eliminated, resulting in gaps and leakage.

        3) There is no oil return groove on the box, and the lubricating oil accumulates in the shaft seal, end cover, joint surface, etc. Under the action of pressure difference, it leaks out from the gap.

       4) The shaft seal structure design is unreasonable. Early reducers used oil groove, felt ring type shaft seal structure, when assembling felt compression deformation, and will seal the joint surface gap. If the journal contact with the seal is not very ideal, the seal will fail in a short time because of the poor compensation performance of felt. Although there are oil return holes on the oil trench, it is easy to plug, and the oil return is difficult to play.

     3. Over-filling: During the operation of the reducer, the oil pool is agitated very severely, and the lubricating oil splashes everywhere in the engine. If the amount of oil is too much, a large amount of lubricating oil accumulates in the shaft seal, joint surface and so on, resulting in leakage.

      4. Improper maintenance technology: in equipment overhaul, due to incomplete removal of dirt on the joint surface, or improper selection of sealants, seals in the direction of reverse assembly, not timely replacement of seals will also cause oil leakage.


       1. Improving the ventilation cap and the inspection hole cover plate: The internal pressure of the reducer is greater than the external atmospheric pressure is one of the main reasons for oil leakage. If we try to balance the internal and external pressure, oil leakage can be prevented. Although the reducer has a permeable cap, but the permeable hole is too small, easy to be blocked by pulverized coal, oil, and each time to open the inspection hole cover, open once to increase the possibility of a leak, so that the original place did not leak also occurred leakage. For this reason, a kind of oil cup type breathable cap was made, and the original thin inspection hole cover plate was changed to 6 mm thick. The oil cup type breathable cap was welded on the cover plate, and the diameter of the breathable hole was 6 mm. It was easy to ventilate and the pressure was equalized.

       2. Flow freely: In order to make the excess oil not accumulated in the shaft seal, the excess oil must flow back to the oil pool along a certain direction, that is, flow freely. The concrete method is to open an inclined oil return groove in the center of the lower bearing pad, and a notch is also opened at the straight mouth of the end cover. The notch is opposite to the oil return groove, so that the excess oil flows back to the oil pool through the notch and the oil return groove.

        3. Improve the shaft seal structure.

          (1) Improvement of the shaft seal of the reducer with half-shaft output shaft: the output shaft of the reducer with belt conveyor, screw unloader, impeller coal feeder and other equipment is half-shaft, so the transformation is more convenient. The reducer is dismantled, the coupling is removed, and the axle seal end cover of the reducer is removed. According to the matching size of the skeleton oil seal, the machining groove of the outer side of the original end cover is turned into a machining groove, and the skeleton oil seal is installed, and the side direction of the spring is inward. If the end cap is more than 35 mm from the inner end face of the coupling, a spare oil seal can be installed on the shaft outside the end cap. Once the oil seal fails, the damaged oil seal can be removed, and the spare oil seal can be pushed into the end cap, thus eliminating the time-consuming and laborious process of understanding the body reducer and removing the coupling.

         (2) Improvement of the shaft seal of the reducer with the output shaft of the whole shaft: the output shaft of the reducer with the whole shaft drive has no coupling, if it is reformed according to the 2.3.1 scheme, the workload is too heavy and unrealistic. In order to reduce the workload and simplify the installation procedure, a divisible end cap was designed and an open type oil seal was tried. When loading the oil seal, the oil seal is sawed to form an opening. The oil seal is put on the shaft from the opening. The opening is butted with adhesive. The opening is upward, then the spring is installed and pushed into the end cover.

       4. Adopt new sealing material: For the leakage of the static sealing point of the reducer, the new polymer repair material can be used to stick and plug. If the static sealing point of the reducer leaks oil in operation, it can be plugged by the surface engineering technology oil surface emergency repairing agent - polymer 25551 and 90T composite repair material, thus eliminating the oil leakage.

      5. Careful execution of maintenance process: in the gear reducer maintenance, to conscientiously implement the technical procedures, oil seal can not be reversed, lip mouth should not be damaged, the outer edge should not be deformed, springs can not fall off, joint surface should be cleaned, sealant smeared evenly, the amount of fuel can not exceed the oil scale.

       6. Wipe: The static sealing point of the reducer can be treated without leakage, but the dynamic sealing point is still slightly leakage due to the aging of the seal, poor quality, improper assembly and high surface roughness of the shaft. Because of the poor working environment, coal dust sticks to the shaft, which makes the oil almost a piece. Therefore, it is necessary to wipe the oil stains on the shaft after the equipment is stopped.

*For more product parameters, size and price, please contact Hangzhou Starred-River Machinery Co., Ltd.




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