Final drives have to endure quite a bit – like high-impact loads, extreme torque, sudden direction changes, and frequent gear changes. You know that when your final drive stops, your machine stops. That means one of your goals should be to keep that final drive running. In this Shop Talk Blog post, we are going to discuss some of the considerations in keeping your final drive running.
Consideration #1: Sufficient Lubrication is Vital
The speed-reducing portion of your final drive, often referred to as the gearbox or the gear hub, needs to stay lubricated. The gears, axles, and bearings inside the gear hub experience extreme forces and the potential for devastating metal-to-metal contact. When those two things are combined, it is a recipe for disaster unless you have sufficient, quality lubrication. Lubrication serves three major purposes in your final drive:
- It reduces friction
- It protects parts from direct metal-to-metal contact
- Conducts heat away
Without enough lubrication, your parts will experience galling, welding, fractures, and more. Failure to check and change your gear oil is the fastest way to destroy a final drive.
When selecting a gear oil for your final drive, keep in mind that there is good reason why the manufacturers recommend a particular grade (and brand): those components were designed with that type of gear oil in mind.
When adding new gear oil or changing it out, be careful to avoid contamination. Contaminated gear oil will not not only defeat the purpose, but it will cause additional damage.
Consideration #2: Leaks Mean Trouble
Leaks mean more than just needing to add more gear oil or hydraulic fluid. Leaks not only allow fluid out, but they also allow contaminants in. As we just discussed, contaminants can do incredible damage to final drive, whether its the planetary side or the hydraulic side, in a short amount of time.
Imagine getting silt in the gears that are converting speed to torque -- those abrasive materials sandwiched between the gear teeth, compressed between them at extremely high 
forces. Soon your gear teeth will look more like gear fangs, pointed and completely ineffective -- gear failure. Or, imagine getting silt in the hydraulic side of your final drive, working its gritty way into the rotator group and scarring up the piston cylinders and piston shoes.
We realize that you can't necessarily pull a machine off the job as soon as you find a leak, but you do need to get those leaks addressed ASAP. Follow manufacturer guidelines for when you need to replace the seals. And check for potential leaks as part of your operator's daily walkaround. It can save you thousands in repair costs.
Consideration #3: Case Drain Filters
If you've read many of our Shop Talk Blog posts, you'll know that clogged case drain filters are one of the major reasons for the damaged final drives that come into our shop. About 90% of final drive motors are going to have a case drain and filter, and if you don't check that filter on a regular basis you will eventually have a final drive that is totaled beyond repair.
Initially, hydraulic pressure builds up because of the clogged case drain line; next, that pressure blows the seal between the planetary hub and the hydraulic hub, allowing high pressure hydraulic fluid inside; if left unattended long enough, the final drive cover plate will either crack or blow off. Our advice is to check your manufacturer's guidelines for how often they recommend you check and change the case drain filter, and follow those guidelines religiously.
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Conclusion: Final Drive Maintenance Pays in Long Run!
You can extend the life of your final drive by keeping your final drive lubricated, checking the case drain filter, and attending to leaks as soon as possible. These simple tasks will help your final drive run as efficiently and have a long service life. Remember -- final drive maintenance always pays off in the long run!
Keep your final drive is good working order through consistent maintenance. However, when normal wear and tear of your heavy equipment means replacement of your hydraulic drive motor check with Texas Final Drive new and reman final drives.
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