Oil leakage occurs soon after the reducer is repaired and installed, which is usually closely related to the process details and improper handling of seals during the assembly process. The following summarizes several core error-prone points in the assembly and sealing process:
1. Irregular cleaning of the joint surface and application of sealant
Insufficient cleaning of the joint surface: When assembling the upper and lower shells, if impurities such as old sealant, iron filings or oil are not completely removed, the joint surface will not fit tightly, forming tiny gaps and causing leakage. In addition, if there are scratches on the joint surface with a depth exceeding 0.25 mm, the sealing effect will be seriously affected.
Improper use of sealant: Poor thickness control when applying sealant (reasonable thickness should be controlled between 0.2 to 0.5 mm). If too little glue is applied, it will not be able to seal; if too much glue is applied, it will be squeezed into the inside of the box when the bolts are tightened. After breaking, it will float in the oil, which can easily block the internal oil passage and cause the bearing to lack lubrication. At the same time, failure to avoid oil holes, oil grooves and threaded holes when applying glue is also a common operating error.
2. The fastener tightening process is missing "secondary retightening"
Many maintenance personnel think that the assembly is complete after using a torque wrench to tighten the bolts to the specified specifications for the first time, ignoring the "creep" phenomenon of gaskets and liquid sealants under pressure. Soft sealing materials will deform after initial compression and cause the connection to loosen by about 10 to 15 percent of the tension. The correct approach is: pause for 15 minutes after the initial tightening, and then retighten for the second time after the gasket is stable to restore the lost pre-tightening force.
3. The shaft end oil seal is not properly equipped and protected.
Lip damage caused by rough assembly: If simple tooling is used when installing the oil seal or even direct knocking is used, it is easy to cause damage or skewing of the lip of the oil seal. For standard operation, a special pressure sleeve should be used, and an appropriate amount of grease should be applied to the outer surface of the fixed sleeve and the space between the main and auxiliary lips of the oil seal, and the oil seal should be pressed in smoothly.
Ignoring the quality of journal processing and foreign matter: If the surface roughness of the rotating shaft is inappropriate (too smooth may cause lip adhesion), or there are burrs or spiral knife marks in the processing, the oil seal will be scratched during press installation. In addition, if the shaft end is not cleaned and residual foreign matter enters the oil seal lip, it will also aggravate wear and cause oil leakage during operation.
4. Failure of the auxiliary oil return structure and ventilation system
Defects in the design and installation of the oil slinger: If a cup-shaped oil slinger that is prone to oil accumulation is used, and the oil guide groove design is unreasonable or the gap is too large, the lubricating oil will not be able to flow back smoothly. It is recommended to replace it with a conical oil sling ring, use centrifugal force to make the oil spirally return along the cone surface, and open an oil return groove in the casing that is inclined toward the inside of the machine.
The breathable cap is clogged or excessive oiling: The heat generated during the operation of the reducer will increase the pressure inside the box. If the breathable hole is blocked by dust or oil, the internal and external pressure difference will push the lubricating oil out of the gap. In addition, if the amount of oil injected exceeds the specified upper limit, the gear will be violently agitated, and a large amount of splashing lubricating oil will accumulate at the shaft seal, eventually breaking through the sealing defense line.
To sum up, the key to avoid rapid oil leakage after installation is to strictly implement joint surface cleaning and standard gluing, implement the secondary re-tightening process of bolts, use special tooling to install the oil seal without damage, and ensure the smooth flow of the oil return tank and ventilation system.
