Damage in Final Drive Gears

The final drive is one of the essential components of excavators. Without this device, you are unable to move your vehicle. It plays a major role in sufficient torque buildup, leading to effective transmission.

Breakage and damage in final drive gears can cost thousands of dollars. Defective gears result in lower efficiency and less power and can damage your engine.

You can prevent the damage if you know the main reason or cause behind them. This article will provide detailed information on the causes of damage in final drive gears. Sounds Good? Read on to find out!

Introduction: Damage in Final Drive Gears

The main difference between a hydraulic motor and a final drive motor is the presence of planetary gears. When these gears experience damage, this will result in major issues.

The role of the planetary gear is to receive the power from the hydraulic motor and convert it into torque. Ultimately this torque causes your machine movement.

The transfer process in the Planetary hub leads to excessive force and excessive stress on the splines and teeth of gears. This is the reason why you should consider damage in final drive gears.

Type of Damages You May Experience in Your Final Drive Gears

1.   Normal Wear and Tear

Wear and tear refer to the gradual loss of material from a part. Wear and tear is a key factors affecting planetary gears’ performance. Wear and tear occur because of excessive loads and friction between the components.

This cause the gear teeth to become pointed because of wear. Pointed gear teeth cannot mesh between other gears teeth within the assembly. This means you will experience very low torque transfer, which means a loss in power.

When this wear exceeds the specific limit, the gear only spins or rotates without transferring torque. When it comes to mechanical components, wear is a normal phenomenon. But accelerated wear and tear are worse.

2.   Issues with Gear Oil

There are several things that lead to the premature wear and tear of gears, but most of them have one main cause: gear oil.

Multiple issues associated with gear oil. Some of the most common issues you may experience include:

There will be no lubrication between the gears when you have low or no oil in the gear assembly. This means the gears are in direct contact while performing their function. This leads to friction buildup, which ultimately contributes to heat buildup. When the gears face such a situation, gear teeth can be damaged.

If the oil you are using is old enough, it will form sludge between the components. The additives present in the oil make it suitable for high load and high force requirements. The sludge results in different coating gears within the assembly with thick film. This makes your planetary hub prone to further damage.

3.   Pitting Phenomenon

Pitting is the phenomenon that occurs when a high-strength metal accidentally runs into another high-strength material. When this happens at high speed, it produces deep indentations in the weaker surface. This type of damage is called pitting.

Pitting is also a big issue; the main cause behind pitting is cyclic stress during contact. Cyclic stress varies.

It pitting results in two major issues. The first issue is that when this happens, the effect is that the corner surfaces remain no longer smooth and polished. This results in a decrease in the smoothness of planetary gears. It also increases friction between the pitch line and teeth.

The second issue is that the pitted material mixes into the gear oil and contaminates. The main concern is how you can avoid these issues. You can do this by using the right kind of gear oil per standards. Make sure to replace it periodically as per requirement.

4.   Contamination

Another thing that can damage your final drive gears is contaminants. Contaminants are parts of the drive components that enter the workings of the planetary hub. Contaminants refer to the foreign materials or chemicals that enter the system and disturb its functions. Here the foreign material represents dirt, dust, sand, etc.

Contaminants can get into the gear surfaces and result in abrasive corrosion. No matter if the oil is present or not, the damage will occur. The reason is when the contaminants are present on the surface, it can double or triple the amount of stress acting there. This stress level increase leads to gouges, scratches, and accelerated wear.

There are many ways contamination can negatively affect a system:

  • It may increase operating temperature and reduce efficiency
  • Causing breakdowns in lubrication or structural failure

You can minimize these issues when you practice cleaning gear oil periodically and preventing leakage if it exists. You can change the filters, as clean filters play their part in effectively cleaning and preventing contamination from foreign objects.

5.   Scuffing/ Scoring

Scuffing/scoring is a rubbing or abrading of the gear caused by high-speed contact with hard, abrasive surfaces. It is referred to as an adhesive wear because metal particles transfer to another metal surface in this wear. From one gear to another gear. This wear results from contact between the gear with no lubricant present.

You can minimize or avoid this by following ways:

  • Always use the right type of gear oil in your final drive
  • Maintain the level of oil in the final drive, keep an eye on it and prevent it from falling below the specific limit
  • Change the oil when needed

6.   Bending/ Cracks

A crack is a stress fracture that forms when the applied forces exceed the ability of a material to resist. A crack may appear in an almost unlimited number of locations. But generally, it does not grow through the material body itself.

You can find cracks on the base of gear teeth, the location where gear teeth end, and on the overall teeth profile. When they initially start to appear, they grow slowly. But when they grow beyond a specific limit, they move at the speed of sound. The cracks may result because of bending fatigue.

Bending fatigue is when an object’s resistance to being bent or deformed suddenly decreases as it bends. When this happens, the object becomes weaker and more susceptible to breaking. The failure may occur due to permanent deformation of certain properties, such as hardness, elasticity, or yield strength.

This causes the tooth of the gear to bend. The reason is as follows:

Bearing Misalignment: Bearing misalignment is mainly due to faulty installation or excessive wear. This causes load variation. The bearing clearance has a great influence on how meshing takes place between the gear teeth.

How To Prevent The Damage in Final Drive Gears?

You can do the following preventive measures to protect your final drive gears from damage. Some of the main measures are as follows:

1.   Maintain Level of Gear Oil

Maintaining the gear oil on time is important for gear life. This means that the engine will not wear out prematurely and will increase power output.

Checking and changing gear oil on time is essential to avoid damaging gears. High-quality gear lubricant helps the longevity of all gears and helps maintain good engine performance over a long period.

The time of changing the gear oil varies and depends on various factors, including:

  • Working frequency
  • Type of environment in which you work
  • Leakage if any
  • Load on your final drive

2.   Leaking Seals Replacement

Seals are a vital component of high-speed hydraulic transmissions. The seals seal the fluid and prevent it from escaping from the transmission. When a seal leaks, fluid can escape from the transmission and cause premature gear failure.

You should determine and replace the seals responsible for oil leakage because low oil level, as mentioned above, is the main source of wear and tear.

3.   Maintain Bearing Alignment

Bearing alignment is setting your bearings and pulleys in position to ensure that proper gear engagement. Without it, gear teeth would not mesh properly with the input shaft, causing premature failure.

If the bearings are not aligned properly with their cradles or hubs, the engine will have to work harder to continue spinning. It also results in poor power transmission as well as wear and tear.

4.   Replace Worn-out Bearings

Most engines fail due to worn-out, deteriorated, and misaligned bearings. This may result in premature failure of the gears and transmission components. Limiting wear is critical to extending engine life.

Replacing these worn components with premium quality parts is key to prolonging the life of your vehicle’s engine/transmission.


Now you know everything regarding damage in final drive gears. You can follow the maintenance mentioned above measures. This will help you in no damage to your final drive gears. By doing this, you can take the most out of your final drive gears, resulting in maximum efficiency and effectiveness.

Xugong Parts are one of the leading companies in China, Singapore and Malaysia, with quality parts and customer service experience that can surpass the competition. Don’t hesitate to contact us if you need any replacements. Xugong Parts Co., Ltd. is looking forward to your inquiry.



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