Influencing Factors And Fault Prevention of Gearbox Oil Leakage

Publish Time: 2026-01-12 Origin: Site

As a core component for transmitting power and motion in mechanical equipment, the reliability and stability of gearbox operation are crucial. However, oil leakage is one of the most common faults of gearboxes. It not only causes lubricating oil waste and environmental pollution but also leads to intensified wear of key components such as gears and bearings, increased temperature, and even serious accidents like equipment shutdown due to poor lubrication. Therefore, systematically analyzing the causes of oil leakage and adopting effective preventive measures are important links in equipment maintenance and management.

01 Influencing Factors of Gearbox Oil Leakage

The causes of gearbox oil leakage are complex and diverse, usually attributable to problems in multiple links including design, manufacturing, installation, use, and maintenance. The main influencing factors are as follows:

1. Design and Manufacturing Factors

Unreasonable design of sealing structure: Improper selection of sealing form (e.g., using oil seals where mechanical seals should be adopted); defects in sealing groove design, such as unreasonable dimensional tolerance or geometric tolerance, resulting in ineffective fitting of seals.
Inadequate rigidity of the box structure: Excessively thin box wall or improper arrangement of reinforcing ribs, which is prone to deformation under long-term load or temperature changes, leading to gaps on the joint surface.
Improper design or selection of vent cap (breather): When the gearbox operates, the temperature rises and the internal pressure increases. If the vent cap is blocked or its ventilation capacity is insufficient, the internal pressure cannot be released in a timely manner, and the lubricating oil will be squeezed out from the seal with the least resistance.
Casting defects: Internal defects such as sand holes and air holes may exist in the box during the casting process, which may penetrate the wall thickness after long-term use and form leakage points.
Insufficient processing accuracy: Substandard roughness of the joint surface and inadequate finish of the journal surface will affect the sealing effect of the seals.

2. Seal Component Factors

Oil seal failure: This is the most common leakage point.

Aging: Rubber seals will harden and lose elasticity when exposed to high temperature and oil environment for a long time, resulting in the disappearance of the interference fit between the lip and the journal.
Wear: Rough, defective, or eccentric journal surfaces will accelerate the wear of the oil seal lip.
Improper installation: Failure to use specialized tools during installation may cause lip flanging, spring detachment, or scratches of the oil seal.

Improper selection or application of sealant:

Wrong type selection: Failure to use special anaerobic flat sealant, or the sealant's oil resistance and temperature resistance do not meet the requirements.
Construction problems: Discontinuous glue application, gaps, excessive thickness or thinness, uncleaned oil stains on the joint surface, and incorrect bolt tightening sequence and torque.

3. Installation and Assembly Factors

Misalignment between the shaft and seals: Misaligned bearing housing holes or bent shafts cause eccentric wear between the shaft and the oil seal during rotation.
Incomplete cleaning of the joint surface: During assembly, old sealant, oil stains, burrs, etc., on the box joint surface are not cleaned thoroughly, directly affecting the sealing effect.
Improper bolt tightening: Insufficient, uneven, or incorrect sequence of tightening torque leads to uneven pressure on the joint surface and the formation of leakage channels.
Excessively high oil level: Adding oil beyond the upper limit specified by the oil level gauge results in severe gear oil churning, and the oil splashes to the vent cap and shaft seal, increasing the risk of leakage.

4. Operation and Maintenance Factors

Abnormal temperature and pressure:

Overheating: Long-term overload operation, poor lubrication, or cooling system failure leads to excessively high oil temperature, which reduces the viscosity of the lubricating oil, enhances fluidity, and makes it easier to seep out from tiny gaps. At the same time, high temperature accelerates the aging of seals.
Pressure buildup: Blockage of the vent cap is the main cause of increased internal pressure.

Improper lubrication management:

Wrong oil selection: Using lubricating oil with inappropriate viscosity or incompatible with sealing materials.
Oil contamination: Mixing of hard particles such as metal debris into the oil will scratch the sealing surface.

Vibration and load impact: Unstable equipment foundation, poor coupling alignment, or drastic changes in load will generate additional vibration and impact. Under long-term action, fasteners may loosen and seal wear may be intensified.

02 Fault Prevention of Gearbox Oil Leakage

To solve the oil leakage problem, a systematic approach of "prevention first, combination of prevention and control" must be adopted.

1. Optimize Design and Manufacturing (Source Control)

Reasonably select the sealing form: Choose the appropriate sealing combination according to working conditions (rotational speed, pressure, temperature), such as adopting the combination of mechanical seal and labyrinth seal for high-speed shafts.
Enhance box rigidity: Optimize the box structure and reinforcing rib layout through finite element analysis to prevent deformation.
Ensure processing quality: Strictly control the processing accuracy, roughness of the joint surface, and the heat treatment and finish of the journal surface.
Select high-quality vent caps: Ensure sufficient ventilation capacity and dust-proof function, and inspect and replace them regularly.

2. Standardize the Installation and Assembly Process

Strict assembly process: Formulate and implement standard operating procedures (SOPs) to ensure the cleanliness of the joint surface and the tightening of bolts according to the specified sequence and torque.
Use specialized tools: Specialized tools such as guide sleeves must be used when installing oil seals to prevent damage.
Ensure alignment accuracy: Ensure that the alignment accuracy between the motor and the gearbox, and between the gearbox and the load is within the allowable range.
Control the initial oil level: Add oil strictly according to the upper and lower limits of the oil level gauge to avoid excess.

3. Strengthen Operation Monitoring and Daily Maintenance

Implement condition monitoring:

Regular spot checks: Focus on inspecting for oil stains at seals, normal oil level, unobstructed vent caps, and abnormal temperature rise of the box during daily inspections.
Oil analysis: Regularly sample and analyze the oil to monitor its viscosity, moisture content, acid value, and wear metal content, which can detect potential problems in advance.
Vibration and temperature monitoring: Use instruments to monitor the vibration and temperature of the bearing housing and detect abnormalities in a timely manner.

Establish a preventive maintenance plan: