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Writer's pictureRALPH COPE

How to Add Years onto the Life of Your Excavator Final Drive



There are two major parts to an excavator's final drive – the hydraulic motor and the gear reduction. The hydraulic motor is fed by multiple lines (ranging from 2 to 5 depending on the size of the machine). These lines feed hydraulic oil into the motor. The motor turns the shaft which in turn drives the sun gear and the planetary gears – those planetary gears then turn the ring gear that then turns the sprockets that mesh into the links and drive the tracks.


What Maintenance You Should be Doing

You need to focus on three key maintenance points. Firstly, you need to make sure the final drives have sufficient clean lubrication. If you don’t change the oil, levels are going to drop and the quality of the oil will decline. Secondly, you must not overlook leaks. Finally, you must keep the case drain filters clean by replacing them at regular intervals.


Let's now dig a little deeper into leaking final drives. The most common reason for a leak is a failed seal. A final drive that is not sufficiently lubricated may result in abrasive contaminants finding their way into the drive and causing the seal to fail. Gear oil levels should be checked about once every 100 hours or once a month. This oil should be changed once a month.


Clogged case drain filters cause major problems for final drive motors. Case drain filters ensure proper final drive motor function. The case drain filter is a relatively small filter located in an aluminum canister in line with the low-pressure case drain. When clean, it is gold or bronze in color. It needs to be checked/changed whenever you change out the other filters on your machine, and any time you change your whole motors.


Bearing oil needs to be checked/changed about every 500 hours. There are drainage holes on the final drive motor hub where the oil is drained and added, though they may be a bit challenging to find if the final drive is dirty.


Undercarriage

Keeping the undercarriage clean is another aspect of final drive maintenance. When the undercarriage gets packed tightly with debris, that debris can loosen the main seal and allow the final drive to start leaking. That, in turn, can let key fluids leak out and allow damaging contaminants inside. Don't forget undercarriage maintenance!


Hydraulic Fluid

Hydraulic fluid should be changed out about every 3,000 to 4,000 hours or per manufacturer instructions. While this deals more with the hydraulic system as a whole, it will also impact hydraulic motor / final drive performance. Contamination in the system, including chemical degradation of the hydraulic oil, can quickly become contaminated in the final drive motor.


When Should You Do Maintenance?

Don’t wait for your final drives to show signs of failing before executing maintenance on them. If the gears and bearings in your planetary system are already shot, changing out the gear oil is not going to help them. It might keep your final drive running another day or two but that is just going to cause even more damage. You need to take action before problems start. If you start performing regular maintenance, you'll be surprised by the change in how it runs and how long it is between breakdowns.


If you're wondering how often you should do maintenance, we will always recommend that you check your OEM handbook. In there, you will find out how often you should check on various items within your machine, including its final drives! The recommendations were developed by the engineers and technicians that designed your machine. Some people may think that the guidelines are just there to sell filters and lubricants, but they were actually developed so that your machine (and final drives) will operate at their peak efficiency.


How Should You Do Maintenance?

There are plenty of YouTube videos that will guide you on how to do the maintenance if you are inclined towards DIY. If you don't feel confident in your own ability to perform maintenance, you can call in a trained mechanic to do the job.


Conclusion

Your final drive literally keeps your machine rolling and represents a significant financial investment. Make sure that you take good care of it and it will perform well for you. Preventative maintenance that includes basic tasks dealing with lubrication, filters, leaks, and keeping the area around the final drive free from packed debris will go far in extending the useful life of your final drive motor.


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