2) During the manufacturing process of the gearbox, the casting is not annealed or aged, and the internal stress is not eliminated, and it will inevitably deform, generate gaps, and cause leakage;

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

4) The design of the shaft seal structure is unreasonable. Early reducers mostly used oil groove and felt ring type shaft seal structure. During assembly, the felt was deformed by compression, and the joint surface gap was sealed. If the journal is not in good contact with the seal, due to the extremely poor compensation performance of the felt, the seal will fail in a short time. Although there are oil return holes in the oil groove, it is very easy to block, and the oil return function is difficult to play.

3. Excessive amount of oil added: During the operation of the reducer, the oil sump was stirred a lot, and the lubricating oil splashed everywhere in the machine. If the amount of oil added is too much, a large amount of lubricating oil will accumulate on the shaft seal and the joint surface, then cause gearbox oil leaking.

4. Improper maintenance process: when the equipment is overhauled, gearbox oil leaking may also be caused due to incomplete removal of dirt on the joint surface, improper selection of sealant, reverse installation of seals, and failure to replace seals in time.

5. The production quality is poor: there are small holes in the casting box, or the precision of the joint surface is not enough, or the output shaft has burrs, these may cause oil leakage.

6. The quality of spare parts is not good, especially oil seals and bearings, which are prone to oil leakage when quality problems occur.

How to deal with gearbox oil leaking?

1. Improve the vent cap and inspection hole cover:

The internal pressure of the reducer is larger than the outside atmospheric pressure, it is one of the main reasons for oil leakage. If you try to balance the pressure inside and outside the machine, oil leakage can be prevented. Although the reducer has a vent cap, the vent hole is too small, and it is easy to be blocked by coal dust and oil stains. And every time you add oil, you must open the inspection hole cover. Once opened, it increases the possibility of oil leakage, so that it does not leak. Leaks also occurred in places. For this purpose, an oil-cup-type breathable cap was made, and the original thin inspection hole cover was changed to 6mm thick. The oil-cup-type breathable cap was welded to the cover. The diameter of the air hole was 6mm, which was convenient for ventilation. Pressure equalization, and refueling from the oil cup when refueling, without opening the inspection hole cover, reducing the chance of oil leakage.

2. Smooth flow:

In order to prevent the excess lubricating oil thrown by the gear on the bearing from accumulating at the shaft seal, the excess lubricating oil must flow back to the oil sump in a certain direction, that is, free flow. The specific method is to open an oil return groove inclined in the machine at the center of the lower shoe of the bearing housing, and at the same time, a gap is also opened at the straight port of the end cover, the gap is facing the oil return groove, so that excess lubricating oil flows through the gap and return to the oil sump.

3. Improve shaft seal structure

1) The output shaft is a half shaft: the output shaft of the reducer of most equipment such as belt conveyors, screw unloaders, and impeller coal feeders is a half shaft, which is more convenient for transformation. Disassemble the reducer, remove the coupling, take out the reducer shaft seal end cover, and machine the groove on the outside of the original end cover according to the size of the supporting skeleton oil seal, install the skeleton oil seal, and the side with the spring inward. When reinstalling, if the end cover is more than 35mm away from the inner end surface of the coupling, a spare oil seal can be installed on the shaft outside the end cover. Once the oil seal fails, the damaged oil seal can be taken out and the spare oil seal can be pushed into the end cover, thereby saving time-consuming and labor-intensive processes.

2) The output shaft is the whole shaft: the output shaft of the reducer driven by the whole shaft has no coupling. If it is modified according to the 3.1 scheme, the workload is too large to be realistic. In order to reduce the workload and simplify the installation procedure, a splittable end cap was designed and an open oil seal was tried. Splittable end cover outer turning groove, take out the spring first when installing the oil seal, saw the oil seal cut into an opening, put the oil seal on the shaft from the opening, butt the opening with adhesive, the opening is upward, then put on the spring and push in the end cover.

4. The use of new sealing materials:

For the leakage of the static seal point of the reducer, a new polymer repair material can be used to block the plug.

5. Carry out the maintenance process carefully:

When the reducer is overhauled, the process regulations must be carefully implemented. The oil seal must not be reversed, the lips should not be damaged, the outer edge should not be deformed, the spring should not be detached, the joint surface should be cleaned, the sealant should be applied evenly, and the amount of oil should not exceed the scale of the oil scale.

6. Wipe:

The static seal point of the reducer can be generally leak-proof. However, due to the aging of the seals, poor quality, improper assembly, and high shaft surface roughness, the dynamic seal point still has slight leakage at the individual dynamic seal points. Because of the poor working environment, coal dust sticks to the shaft and looks almost oily, so you need to wipe the oil on the shaft after the equipment stops running.

7. Improve processing accuracy and factory quality control, and use better spare parts.