Final drive troubleshooting – 8 common issues

Drive motors play a crucial role in the functionality of tracked machines, serving as a key component that can significantly impact operational efficiency. The repercussions of drive motor failure are not to be underestimated, as they can lead to costly downtimes and, in severe instances, render equipment completely immobilized in the field. By examining the prevalent causes of final drive failure, we aim to equip you with the knowledge necessary to steer clear of improper operating practices. This understanding will not only help you avert potential issues but also substantially prolong the lifespan of your drive motors, ensuring optimal performance and longevity for your machinery.

What is a final drive?

A final drive, referred to as a drive reducer or travel motor, serves as a pivotal component within the drive unit of machinery. It plays a crucial role in enhancing torque by slowing down revolutions at the drive wheels. This feature not only facilitates smoother navigation across challenging terrains but also alleviates the burden on preceding drive elements. Primarily utilised in construction equipment, notably tracked excavators, and utility vehicles tailored for rugged environments, final drives are indispensable in ensuring optimal performance.

Typically, a final drive comprises two key systems: a hydro motor and a mechanical gearbox, often in the form of a satellite sprocket box. These intricately crafted components excel in transferring propulsion efficiently. Through diligent usage and regular maintenance practices, a final drive can operate seamlessly over an extended period, providing years of reliable service.

 

Common Issues with Final Drives

Final drives, like any other machine part, are susceptible to malfunction. Below are 8 of the most frequently encountered issues with final drives:

Oil Leakage from Gearbox Cover Plate: 

Gear oil plays a crucial role in ensuring the smooth operation of the final drive. Without it, the gears are at risk of overheating and premature wear. If you observe oil leaking from underneath the gearbox cover plate, prompt investigation is necessary.

In such cases, the leakage may stem from either a distorted cover or excessive pressure within the gearbox. Addressing a damaged cover plate is a relatively straightforward task that involves replacing the affected part. However, if the issue is related to built-up pressure, the situation becomes more complex and potentially hazardous. Prolonged pressure build-up can lead to catastrophic gearbox failure. If you suspect high pressure levels, it is imperative to seek assistance from a professional service centre without delay.

Oil leaking from the ring gear:

The presence of oil leaking from the ring gear is commonly indicative of a worn-out or damaged floating seal. This component plays a crucial role in maintaining the integrity of the gearbox by preventing oil leakage. To rectify this issue, it is recommended to promptly replace the compromised floating seal. By doing so, the gearbox will regain its functionality and ensure optimal performance.

Gearbox oil level too high:

An excessively high gearbox oil level can lead to detrimental consequences, akin to having insufficient gear oil. The excessive heat generated by the operational gears causes the oil to expand, resulting in the displacement of seals, leakage, and the buildup of hydraulic pressure. It is essential to avoid filling the gearbox with oil up to the cap to prevent these complications.

If the gearbox oil level remains high despite adhering to the appropriate oil quantity during refills, the root cause may be attributed to worn-out bearings or seals located between the final drive motor and the gearbox. In such instances, replacing these components is advised to restore the oil level to its standard capacity. This proactive measure will effectively address the issue and ensure the gearbox operates within optimal parameters

Excessive noise:

When operating heavy equipment, it is crucial to be attentive to the sounds it produces, as these can indicate underlying issues that may require immediate attention. Excessive noise coming from the final drive should never be disregarded, as it could be a warning sign of potential problems that, if left unaddressed, may escalate into costly repairs. Here are three common issues that can lead to excessive noises in the final drive:

- Insufficient oil level in gearbox: This issue is often a result of leaks or inadequate maintenance of the final drive. If topping up the oil does not resolve the problem, it may be necessary to overhaul the gearbox or motor to prevent further damage.

- Worn-out bearings/gears: Over time, lack of maintenance or reaching the end of the final drive's service life can cause bearings and gears to wear out. In such cases, replacing the travel motor with a new one is recommended to ensure optimal performance and prevent further deterioration.

- Impurities in the oil: Neglecting maintenance can lead to impurities, such as metal swarf from poorly lubricated gears, contaminating the oil. This results in increased friction and accelerated wear and tear on components. To address this issue, it is advisable to disassemble the motor and gearbox, clean them thoroughly, and replace any worn-out parts. Alternatively, investing in a new travel motor may be a more effective solution in the long run.

By promptly identifying and addressing these issues causing excessive noise in the final drive, operators can prevent more significant problems and ensure the efficient operation of heavy equipment.

Hot gearbox casing/ring cover plate

Enhance the performance and durability of your gearbox with the Hot Gearbox Casing/Ring Cover Plate. When faced with leakages, there are two potential causes, each with differing levels of severity.

- Low oil level: Easily rectified by topping up the oil to the appropriate level.

- Worn bearings: This issue necessitates a more comprehensive solution, requiring a gearbox overhaul to ensure continued smooth operation.

By addressing these issues promptly and effectively, you can maintain the optimal functionality of your gearbox for prolonged use.

Difficulty in terrain-climbing

When your machinery, such as an excavator, encounters difficulties in traversing rugged terrain, the issue is often attributed to one of the following three factors:

- Insufficient Power: This is frequently caused by low hydraulic pressure in the hydro motor. To address this, start by examining the hydraulic pressure levels. Subsequently, inspect the hydraulic fluid levels and search for any potential leaks. If the root cause is not immediately apparent, it is advisable to seek assistance from a professional service centre.

- Excessive Wear on the Travel Motor: In instances where the travel motor has become excessively worn-out, the most effective solution is to procure a replacement motor to restore optimal performance.

- Excessive Wear on the Gearbox: Similarly, when the gearbox shows signs of excessive wear and tear, the recommended course of action is to replace the gearbox to ensure seamless operation and longevity of the machinery.

Motor works but gearbox fails to move

If you are experiencing a situation where the motor is functioning, but the gearbox is failing to engage, there are three main potential scenarios to consider. Each case requires a specific course of action to rectify the issue:

- Broken Motor Shaft: In the event of a broken motor shaft, it is essential to replace both the shaft itself and the 1st drive gear or sun gear. By addressing both components, you ensure the proper functioning of the gearbox and motor system.

- Broken Drive Shaft: If the issue lies with a broken drive shaft, this component is the sole element requiring replacement. By focusing on replacing the drive shaft, you can restore the gearbox's functionality without the need for additional repairs.

- Broken Sun Gear/1st Drive Gear: Lastly, a situation involving a broken sun gear or 1st drive gear necessitates the replacement of the damaged gear. By replacing the faulty gear, you can resolve the gearbox issue and ensure its smooth operation.

By identifying the specific cause of the gearbox malfunction and addressing it accordingly, you can effectively troubleshoot the problem and restore the gearbox's functionality.

Motor idling

When a motor idles in the final drive, it may be due to a broken motor shaft or worn cylinder block/friction plate. To address this issue, it is recommended to replace the faulty element causing the idling. By replacing the broken motor shaft or worn cylinder block/friction plate, you can effectively resolve the idling problem in the final.

 

Overview of Final Drive Challenges

The majority of final drive issues stem from a lack of proper maintenance. Nearly all significant malfunctions can be prevented by diligently tending to your equipment and promptly addressing any concerns. By doing so, you can significantly reduce both the time and financial resources required for repairs, given the high cost associated with replacing travel motors. With consistent care and attention, you can ensure that your final drive operates efficiently throughout its entire lifespan.

 

Popular final drives

 

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