Are you ready to see some of the most horrifying final drive failures?
Clogged Case Drain
If you don’t change the case drain filter often enough, the case drain line will get clogged. This, in turn, leads to a build-up of pressure inside the hydraulic motor. As the pressure builds, that fluid has to go somewhere! After blowing the oil seal, the next destination is inside planetary side of the drive where the pressure continues to build. Eventually, the final drive cover or hub itself will blow apart.
Damaged Rotator Group
Here is a severely damaged piston shoe from a rotator group on a Bobcat final drive. You’ll notice the significant chunk of metal missing from the edge, which is never good. That chunk ended up in the hydraulic fluid and caused some serious cascade damage.
Below you can see a totally wrecked rotator group, complete with scarred piston shoes and some piston shoes missing! You have to wonder what could cause those piston shoes to blow off inside a final drive. It took us a while to find the pieces of them.
And here are the missing pieces! You’ll notice how badly those piston shoes are chewed up. This is never a good thing to find in a final drive when performing a diagnosis. These parts are totaled and will have to be replaced.
If you leave a leak untreated, especially if it is coming from the floating face seals, then not only can lubricant leak out but debris and mud can make its way in. The result is a thick sludge that will end up destroying your final drive. This is not lubricating -- this is compounding surface damage.
Leaks shouldn’t just be topped off. When a seal begins to fail, it will be much cheaper to send in your drive to get the seals replaced than to buy a new or re-manufactured final drive, like happened with the drive shown below — it was simply to damaged to be repaired.
When bearings start to wear out, they really need to replaced. If you don’t replace them in a timely manner, then they can start tearing up things in a domino-effect. To prevent bearing failure, check and change the gear oil according to manufacturer guidelines and avoid mixing different types of gear oil and lubricant.
Eventually, parts will wear out. In one of the drives that were sent to us for diagnosis and repair, we discovered that the teeth had worn so badly on the upper and lower drives shafts that they couldn’t successfully couple anymore. That meant the final drive would not turn!
Conclusion: Follow Manufacturer's Guidelines
If you don’t want to see this type of damage to your final drive, then follow the manufacturer’s guidelines for maintenance. As soon as you know there is a seal leaking or your suspect that something is damaged or worn, please get your final drive checked out. Preventative maintenance can save you thousands of dollars in the long run.