When a Final Drive Has Gone As Far As It Will Go

Do you know what signs to look for when you suspect your final drive has gone about as far as it can go? Well, then that’s the purpose of this Shop Talk blog post. Let’s get started by talking about excessive heat ...

Excessive Heat

If water vaporizes the instant it touches your final drive, then you have a problem on your hands. It’s not necessarily the final drive, though. It could be that the hydraulic fluid is too hot. On the other hand, it could be something about to cause more damage, like a brake that won’t completely release, worn out bearings, or not enough gear oil. An overheating final drive can be a signal of impending problems and should not be ignored.

Excessive Noise

We know heavy equipment is noisy, so if you or an operator can hear your final drive then you know something very bad has happened. Excessive noise usually has one of two causes, either of which can be devastating to its operation: too low on gear oil or worn out bearings.

Bearings have a finite life, and will eventually wear out. When they do wear out, they can no longer provide the low-friction surfaces and key support that they need to. This in turn causes other parts to be damaged along the way. In fact, the image above shows what happens to a final drive when the bearings aren’t replaced–catastrophic failure.

Running a final drive that is low on  gear oil will damage it – contrary to what many people may believe. A common belief is that as long as the gears are lubricated everything will be fine. However, if you don’t have the suggested amount of lubrication for the gears and bearings, they won’t be protected from heat and metal-on-metal contact points. This will guarantee a failure the would be both catastrophic and beyond repair.

Keep in mind, also, that if you are frequently adding fluid to the unit, you may be overlooking a potential leak from a seal failure.

Leaks

A leak by itself doesn’t mean that your final drive is about to fail. However, a leak that is left unaddressed will certainly sound the death knell for your final drive. A leak doesn't only allow vital hydraulic fluid and gear oil to leak out; it allows damaging contaminants to creep in as well.

When you find a leak, you should get those seals checked and replaced as soon as feasible. If you don’t, the inside of your final drive might end up looking like this Comer final drive off a Bobcat 331.

Cover Plate Gone

If your cover plate blows off, we can’t rebuild your final drive. It’s not that we don’t want to; we simply can’t. If your core is split like the one shown below, we can’t do much for that, either.

The excessive pressure it takes to blow a cover plate off or even crack it does terrible damage to the components in your final drive, like blown piston shoes and dissembled bearings. A blown cover plate is the end for your final drive. This problem is caused by neglecting a simple maintenance step: regularly checking the case drain filter.

Conclusion

Don’t neglect the maintenance on your final drive until it’s died! Check and change the gear oil, address leaks as soon as you can, and don’t ignore symptoms like excessive noise or overheating. And don’t neglect the case drain filter until enough pressure builds up to blow the cover plate off.