Causes of Final Drive oil leaks and unusual noises

  In daily excavator operation, the travel assembly plays a crucial role in equipment movement, relocation, and operation in complex terrain. Abnormal noises or oil leaks in the travel assembly not only affect equipment efficiency but can also lead to more serious mechanical failures, increasing maintenance costs and downtime.

  Many users, when discovering travel assembly malfunctions, often only focus on surface symptoms such as "abnormal noises" or "oil leaks," neglecting the underlying causes. Today, we will analyze the common causes of abnormal noises and oil leaks in the travel assembly to help users identify problems promptly and take correct maintenance measures.

Common Causes of Abnormal Noises in the Travel Assembly❓

1. Wear or Damage to Planetary Gears and Sun Gears

The travel reducer consists of multiple sets of planetary gear mechanisms. When gears operate under high loads for extended periods, or when wear occurs due to insufficient lubrication, the gear meshing clearance gradually increases.

Common Manifestations:

 ❗ A metallic friction sound, such as a "clicking" or "grinding," occurs during travel; 

 ❗ the greater the equipment load, the more pronounced the sound; 

 ❗ in severe cases, vibration may accompany the noise.

Continued use may lead to serious malfunctions such as missing or broken teeth on the gears.

 2. Bearing Wear or Damage

Bearings support internal rotating components and ensure stable operation. When bearings wear down after prolonged use, the balls become damaged, or the cage breaks, abnormal noise will be generated.

Common Symptoms:

 ❗ A continuous "humming" sound during movement;

 ❗ The sound becomes more pronounced at higher speeds;

 ❗ The sound disappears after the equipment stops.

If not addressed promptly, bearing damage can also cause output shaft wobble, further leading to oil leaks.

3. Hydraulic Motor Internal Wear

As the power source for the walking system, the hydraulic motor's core components, such as the plunger, distributor plate, and swashplate, may experience wear after prolonged use.

Common Symptoms:

 ❗ Noticeable abnormal noise during start-up;

 ❗ Weak movement;

 ❗ Slower movement speed;

 ❗ Accompanied by system overheating.

This type of fault not only affects equipment performance but also accelerates the wear of the entire walking system.

4. Insufficient or Degraded Lubricating Oil

The gears and bearings inside the reducer require gear oil for lubrication and heat dissipation.

The following situations will lead to decreased lubrication, resulting in abnormal noise and accelerated wear of internal parts:

 ❗ Prolonged lack of gear oil change;

 ❗ Gear oil deterioration;

 ❗ Insufficient gear oil level;

Common Causes of Oil Leakage in the Travel Assembly❓

1. Damaged Floating Oil Seal

The floating oil seal is one of the most important sealing components of the travel reducer and is also the most common point of failure for oil leakage.

Causes of damage include:

 ❗ Long-term wear;

 ❗ Scratches on the sealing surface;

 ❗ Improper installation;

 ❗ Sediment entering the sealing area.

Common symptoms:

 ❗ Oil stains around the drive wheel;

 ❗ Oil seepage persists even after shutdown;

 ❗ Leakage becomes more pronounced with longer operating time.

2. O-ring Aging and Failure

Multiple O-rings exist inside the travel assembly.

With increased use, the O-rings may experience: 

 ❗ Aging and cracking;

 ❗ Loss of elasticity;

 ❗ Deformation during installation;

This can lead to leakage of hydraulic oil or gear oil.

3. Bearing Wear Causing Output Shaft Wobble

Many users find that oil leakage persists even after replacing the floating oil seal. The root cause is often not the oil seal itself.

When the bearing is severely worn:

 ❗ The output shaft wobbles radially;

 ❗ The floating oil seal experiences uneven stress;

 ❗ The sealing surfaces cannot properly adhere;

Ultimately leading to continuous oil leakage.

Therefore, during maintenance, the bearing condition must be checked simultaneously, not just the oil seal.

4. Housing Cracks or Mating Surface Seal Failure

Under long-term impact loads and harsh operating conditions, the gearbox housing may develop cracks, or the mating surface sealant may fail.

Common Manifestations:

 ❗ Obvious oil stains on the housing surface;

 ❗ Continuous oil seepage near the mating surfaces;

 ❗ Oil contamination around the fastening bolts.

5. Clogged Vent Hole

The vent hole is responsible for balancing the internal pressure of the gearbox.

If the vent hole is blocked by dirt or oil:

 ❗ Internal pressure continues to rise;

 ❗ Gear oil expands due to heat;

 ❗ Ultimately, it is squeezed out from the oil seal or sealing ring.

This situation is particularly common in high-temperature construction environments.

Special attention should be paid when abnormal noise and oil leakage occur simultaneously.

If the equipment exhibits the following simultaneously:

 ❗ Abnormal noise during travel;

 ❗ Oil leakage from the travel assembly;

 ❗ Decreased travel speed;Weak travel;

This likely indicates severe wear on internal gears and bearings.

The typical failure progression is:

 ❗ Bearing or gear wear → Increased internal clearance → Output shaft wobble → Damaged floating oil seal → Gear oil leakage → Insufficient lubrication → Further damage to gears and bearings.

If only the oil seal is replaced without inspecting internal parts, the fault will often recur, eventually leading to the complete failure of the travel assembly.

Daily Maintenance Recommendations

To extend the service life of the travel assembly, users are advised to:

✅ Regularly check the gear oil level and condition;

✅ Change the gear oil according to the maintenance schedule;

✅ Regularly inspect the floating oil seal and other seals;

✅ Clean the vents promptly;

✅ Stop the machine immediately upon detecting abnormal noise,Avoid prolonged overload operation.

Early detection and prompt handling can not only reduce maintenance costs but also effectively prevent downtime losses caused by malfunctions in the walking assembly.

For equipment exhibiting abnormal noises, oil leaks, or weak movement, it is recommended to conduct a professional inspection as soon as possible and replace worn parts promptly to ensure continuous and stable operation.