Failure Items in a Final Drive Motor

21Y-60-12101 for KOMATSU PC200LC-7


The final drive motor in heavy machinery, particularly in excavators, is crucial for its operation. It is responsible for converting hydraulic power into mechanical motion, enabling the tracks or wheels to move. However, like any mechanical component, final drives are susceptible to failure due to various factors. This blog will delve into the most common failure items in a final drive motor, including the main bearing, gears and gear bearings, upper and lower shafts, and seals. We’ll also discuss the most common causes of failure and provide tips for maintaining your final drive motor to extend its lifespan.


When purchasing a final drive motor, one of the most important aspects to consider is the warranty. A limited lifetime warranty provides peace of mind, ensuring that any defects or issues that arise under normal operating conditions will be addressed by the manufacturer. This warranty typically covers parts and labor for repairs, giving you confidence in the durability and reliability of your final drive motor.

Benefits of a Limited Lifetime Warranty

  • Protection Against Defects: A limited lifetime warranty ensures that any manufacturing defects or material issues will be repaired or replaced at no cost.
  • Cost Savings: Unexpected repairs can be costly. A warranty can save significant amounts of money on repairs and replacements.
  • Increased Resale Value: Equipment with a valid warranty often has a higher resale value as it assures potential buyers of its quality and maintenance history.

Understanding Warranty Terms

It’s essential to understand the specific terms and conditions of the warranty. Look for coverage details, any exclusions, and the process for filing a claim. Ensure that regular maintenance and proper use are adhered to, as these are often required to keep the warranty valid.

Navigating the main menu of a parts supplier’s website can help you quickly find the necessary components and information for your final drive motor. Here are some critical sections to look for:

Parts and Components

Most suppliers will have a dedicated section for final drive parts, including bearings, gears, seals, and shafts. This section allows you to search for specific parts by category or compatibility with your machinery.

Manuals and Guides

Access to manuals and maintenance guides can be invaluable. These resources provide detailed instructions on diagnosing issues, performing repairs, and conducting regular maintenance.

Customer Support

final drive motor
track motors

A reliable parts supplier should offer robust customer support. Look for contact information, live chat options, and troubleshooting assistance to help you resolve any issues you encounter.

Shop By Category

When shopping for final drive components, categorizing products can streamline the process. Here are some common categories you might find:


Bearings are critical for the smooth operation of the final drive. This category should include various types of bearings used in final drives, such as main bearings and gear bearings.


Gears are essential for the power transmission within the final drive. This category should offer different types of gears, including planetary gears and sun gears, compatible with various models.


Seals prevent contamination and maintain the integrity of the hydraulic system. Look for a range of seals, including oil seals and dust seals, specific to your final drive motor.


Shafts are integral to the mechanical movement of the final drive. This category should feature upper and lower shafts and related components.

Shop By Brand

Different brands of heavy machinery and final drives may require specific parts and components. A “Shop By Brand” section helps you quickly find compatible parts for your equipment. Here are a few popular brands:


Caterpillar, often referred to as CAT, is a leading manufacturer of heavy machinery. This section should include final drive components specific to CAT equipment, ensuring compatibility and reliability.


Komatsu is another well-known brand in the heavy machinery industry. Look for parts and components designed for Komatsu final drives to maintain optimal performance.


Hyundai construction equipment is widely used in various industries. This section should feature final drive parts compatible with Hyundai machinery.

Site Information

Understanding the site’s features and services can enhance your shopping experience. Here are some essential elements to look for:

Shipping and Delivery

Check the shipping and delivery options available. Ensure that the supplier can deliver parts promptly to minimize downtime.

Return Policy

A clear return policy is crucial. Understand the terms for returning parts, especially if they are defective or incompatible with your equipment.

Customer Reviews

Customer reviews provide insights into the quality of products and the reliability of the supplier. Look for testimonials and ratings to gauge customer satisfaction.

The Most Common Failure Items on a Final Drive Motor

Final drive motors are complex components with several critical parts that can fail over time. Understanding these common failure items can help you diagnose issues early and prevent further damage.

Main Bearing

The main bearing is one of the most critical components of a final drive motor. It supports the weight of the machinery and ensures smooth rotation of the drive motor.

Symptoms of Main Bearing Failure

  • Noise: Grinding or knocking noises indicate that the main bearing is worn or damaged.
  • Vibration: Excessive vibration during operation can signify bearing issues.
  • Overheating: A failing bearing can cause the final drive to overheat due to increased friction.

Diagnosing Main Bearing Issues

To diagnose main bearing issues, perform a visual inspection for wear and listen for unusual noises during operation. Checking for excessive play or movement in the bearing can also indicate problems.

Replacing the Main Bearing

Replacing the main bearing involves disassembling the final drive, removing the old bearing, and installing a new one. Ensure you use the correct tools and follow the manufacturer’s guidelines for bearing replacement.

Gears and Gear Bearings

Gears and gear bearings are essential for power transmission within the final drive. They convert hydraulic power into mechanical motion, enabling the tracks to move.

Symptoms of Gear and Gear Bearing Failure

  • Noise: Unusual noises, such as clicking or grinding, can indicate gear or bearing wear.
  • Reduced Power: A loss of power or efficiency in the final drive can signify gear issues.
  • Visual Damage: Inspecting the gears for visible damage, such as chipped teeth or excessive wear, can help identify problems.

Diagnosing Gear Issues

To diagnose gear issues, perform a visual inspection and listen for noises during operation. Check for proper alignment and ensure that the gears are adequately lubricated.

Replacing Gears and Gear Bearings

Replacing gears and gear bearings requires disassembling the final drive, removing the damaged components, and installing new ones. Ensure that the new gears and bearings are correctly aligned and lubricated to prevent future issues.

Upper and Lower Shafts

The upper and lower shafts are integral to the mechanical operation of the final drive. They transmit power from the hydraulic motor to the gears.

Symptoms of Shaft Failure

  • Noise: Unusual noises during operation can indicate shaft issues.
  • Vibration: Excessive vibration can signify problems with the shafts.
  • Visible Damage: Inspecting the shafts for cracks or wear can help identify potential issues.

Diagnosing Shaft Issues

To diagnose shaft issues, perform a visual inspection and listen for unusual noises. Check for proper alignment and ensure that the shafts are not bent or damaged.

Replacing Upper and Lower Shafts

Replacing the shafts involves disassembling the final drive, removing the old shafts, and installing new ones. Ensure that the new shafts are properly aligned and lubricated to prevent future issues.


Seals are crucial for maintaining the integrity of the hydraulic system and preventing contamination.

Symptoms of Seal Failure

  • Oil Leaks: Oil leaking from the final drive indicates seal failure.
  • Contamination: Contaminants in the hydraulic oil can signify seal issues.
  • Reduced Performance: A loss of hydraulic power can indicate problems with the seals.

Diagnosing Seal Issues

To diagnose seal issues, inspect the final drive for oil leaks and check the hydraulic oil for contaminants. Ensure that the seals are properly installed and not damaged.

Replacing Seals

Replacing seals involves disassembling the final drive, removing the old seals, and installing new ones. Ensure that the new seals are correctly seated and not damaged during installation.

Most Common Cause of Failure for a Final Drive

Several factors can contribute to the failure of a final drive motor. Understanding these causes can help you take preventive measures to extend the lifespan of your equipment.

Lack of Maintenance

Regular maintenance is crucial for the longevity of the final drive. Neglecting maintenance tasks, such as oil changes and inspections, can lead to premature failure.


Contaminants, such as dirt and debris, can enter the final drive and cause significant damage. Ensure that seals are intact and regularly check for contaminants in the hydraulic oil.


Operating the machinery beyond its designed capacity can place excessive stress on the final drive, leading to failure. Follow the manufacturer’s guidelines for load limits and ensure that the equipment is used correctly.

Improper Installation

Incorrect installation of components, such as bearings and seals, can lead to premature failure. Ensure that all parts are installed correctly and follow the manufacturer’s guidelines.

Wear and Tear

Normal wear and tear over time can lead to the failure of final drive components. Regular inspections and maintenance can help identify and replace worn parts before they cause significant damage.


Diagnosing and addressing issues with your mini excavator’s final drive motor is essential for maintaining the efficiency and longevity of your equipment. By understanding the common failure items, such as the main bearing, gears and gear bearings, upper and lower shafts, and seals, you can take preventive measures and perform timely repairs. Regular maintenance, proper installation, and following the manufacturer’s guidelines can significantly extend the lifespan of your final drive motor and prevent costly downtime.


How Often Should the Final Drive Be Inspected?

The final drive should be inspected regularly, with visual checks every 250 hours of operation and more detailed inspections, including oil analysis and hydraulic pressure tests, every 1,000 hours.

Can a Faulty Final Drive Be Repaired, or Does It Need to Be Replaced?

Depending on the severity of the damage, a faulty final drive can sometimes be repaired by replacing worn components such as gears and bearings. However, severe damage may require a complete replacement of the final drive.

What Type of Lubrication Is Best for Final Drives?

The best type of lubrication for final drives is typically a high-quality gear oil that meets the manufacturer’s specifications. This oil should have the appropriate viscosity and contain additives that protect against wear, corrosion, and extreme pressure.

How Can I Improve the Longevity of My Excavator’s Final Drive Motor?

To improve the longevity of your final drive motor, perform regular maintenance checks, use the recommended hydraulic fluid, ensure proper filtration to keep the fluid clean, and address any leaks or unusual noises promptly. Additionally, operating the excavator within its designed parameters and avoiding excessive loads can help reduce stress on the final drive motor.

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