Essential Insights on Final Drive Maintenance

Repairing an excavator's final drive is undeniably an expensive and time-consuming endeavour. The financial implications extend beyond the cost of replacement parts, encompassing significant losses incurred from machine downtime. Therefore, regular inspection and maintenance of this vital component of the suspension system is essential to ensure optimal excavator performance.

 

Why is regular final drive maintenance essential?

Regular maintenance of the final drive is paramount for the longevity and efficiency of tracked excavators. These components are subjected to significant loads, and without diligent upkeep, they can deteriorate rapidly. Neglecting maintenance poses not only a risk of irreversible damage to the final drive itself but also jeopardises the integrity of the entire hydraulic system.

The wear and tear of the final drive's operational elements can lead to contamination, which, if left unchecked, may be transferred through the hydraulic oil to other interconnected parts of the machinery. This can result in widespread failures that are often costly and time-consuming to rectify.

Investing a few moments in routine maintenance of your excavator's final drive can save considerable time and financial resources in the long run. Should the need arise to replace your final drive, we offer a comprehensive selection of replacement final drives suitable for crawler excavators from various manufacturers.

 

The most important maintenance tasks

To maintain the optimal performance of your final drive and prevent any potential failures, it is essential to adhere to a regular maintenance schedule. Below are the key tasks that should be performed to ensure everything operates smoothly:

 

Gear Oil Level Check

It is imperative to monitor the final drive gear oil level at specific intervals to ensure proper functioning. Experts recommend the following schedule for checking the oil level:

- After installing a new final drive

- After 100–150 hours of operation

- Subsequently, every 500–800 hours of operation

For precise instructions, please refer to the operator’s manual (O&M).

Steps to Check the Oil Level

To check the oil level in your final drive, follow these systematic steps:  

Initial Preparation 

Begin by inspecting the cover plate of your final drive motor. After removing the cover, you will observe two or three plugs, depending on the model of your final drive.

Understanding Plug Configuration

- For a two-plug system, the plugs are typically arranged at a right angle (90°) to each other.

- In a three-plug system, the plugs will generally be in a linear arrangement, with two located at opposite edges and one in the centre.  

Positioning for Inspection

- For two plugs: Position the upper plug at the 12 o’clock position and the lower plug at the 3 o’clock position. The manufacturer's logo or a designated hole sign can assist in achieving the correct orientation.

- For three plugs: Ensure that the filler hole cap is at the top, which is usually marked as the "fill line."

Cleaning the Area

Prior to removing any plugs, meticulously clean the final drive to eliminate any debris, such as sand, mud, or dirt, particularly around the plugs. This precaution helps prevent contaminants from entering the gear oil during the removal process.  

Removing the Plugs 

Carefully remove the plugs. In the case of a two-plug system, remove one plug at the top and the other at the bottom. For a three-plug system, remove the middle plug first, followed by the top plug. If necessary, a hammer may be required to loosen the plugs.

Checking the Oil Level

Once the plugs are removed, check the oil level. The gear oil should be level with the centre hole at the 3 o’clock position. If the oil level is below this point, it will be necessary to add oil until it reaches the appropriate level.  

Final Steps

After replenishing the oil, securely replace the plugs. It is crucial to adhere to the guideline that the gear oil should not exceed half of the final drive’s total capacity.

 

Change out the gear oil

Changing the gear oil is an essential maintenance task that should be performed in accordance with the manufacturer's recommendations outlined in the operator’s manual. To ensure a smooth and efficient process, it is advisable to undertake this task while the oil remains warm, as this facilitates easier drainage. Below are the detailed steps to successfully change the gear oil:

- Begin by positioning the final drive so that the designated plugs are aligned at the 3 and 6 o’clock positions (for two holes) or with the plug marked “drain” located at the bottom (for three holes). The lower hole is designated for draining oil, while the upper or middle hole serves to ventilate the system.

- Prior to commencing the oil change, clean the surface of the final drive thoroughly. Proceed to remove the lower cap first, followed by the upper cap. If necessary, utilise a hammer to assist in loosening these caps.

- As the oil drains through the lower hole, closely inspect it for any metallic shavings. The presence of such shavings may indicate damage to the gear mechanism, signalling that the final drive requires servicing or should be replaced entirely.

- Once all the old oil has been completely drained, you can begin adding the new oil. If you are working with two holes, simply invert the plugs so that the lower one is positioned on top. For three holes, utilise the third hole, which is typically marked “fill,” for adding oil.

- Carefully pour the new oil through the top hole, ensuring that you use the same type of oil as previously used. It is crucial to avoid mixing different types of oil, as this can lead to operational issues.

- After filling the final drive to the appropriate level, securely install the new plugs to complete the process.

 

Inspecting the Case Drain Filter

The case drain filter is a critical component found in nearly every final drive motor, positioned along the return line to the hydraulic tank. Its primary function is to capture impurities from the hydraulic fluid as it exits the power motors. Regular inspection and timely replacement of this filter are essential; neglecting this maintenance task can lead to clogging. A clogged filter may result in increased pressure within the system's components, potentially causing catastrophic failures.

Identifying the location of the case drain filter can pose a challenge, as an excavator may house up to five hydraulic filters. It is advisable to consult with a service centre for precise information. The service professionals will verify the model and serial number of the excavator to determine the specific hydraulic filters present and their respective locations. Additionally, they can provide guidance on the recommended frequency of replacement and the appropriate techniques, as outlined in the machine’s manual.

When preparing to remove the filter, connect the drain lines to prevent contamination and minimise the loss of hydraulic fluid. Carefully unscrew the filter and assess the condition of the filter element, which is typically conical and constructed from sintered bronze. It is imperative to replace the filter elements if they show signs of deterioration or if they have lost their bronze appearance.

 

A leaking final drive

A leaking final drive can pose significant challenges in equipment operation, making it essential to conduct thorough leakage checks on a daily basis before commencing work. It is important to be aware that there are two primary types of leaks associated with a final drive: hydraulic leaks and gear oil leaks.

To identify a gear oil leak, one should carefully inspect for any traces of oil behind the gear or observe for drops of oil accumulating on the tracks of a tracked excavator. Such leaks are typically linked to the mechanical face seal, and it is crucial to address them promptly to prevent further complications and ensure optimal performance.

Hydraulic fluid leaks can arise from various sources, including a damaged hose, which can often be repaired swiftly and efficiently. However, leaks may also indicate more serious issues, such as degradation of hydraulic oil, problems with the hydraulic motor, or a clogged filter within the final drive system. Timely diagnosis and resolution of these leaks are vital to maintaining the integrity and functionality of the equipment.

 

How often should I do final drive maintenance?

Determining the frequency of final drive maintenance is not straightforward, as it varies based on the specific excavator model and its usage intensity. However, it is essential to prioritise preventative maintenance for final drives.

To establish an effective maintenance schedule, refer to the Operation and Maintenance Manual provided by the manufacturer. This manual is crafted by engineers who possess in-depth knowledge of the machine's design and maintenance requirements. It is important to note that the frequency of maintenance will increase with the intensity of the travel motor's use. Additionally, continuous monitoring of the final drive's condition is advised, ensuring that the oil level is topped up as necessary.

 

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