The average life expectancy of your face seals varies from 4,000 to 12,000 hours. There are several factors at work when it comes to how long they last, and a good understanding of them will help you lengthen the life of your face seals.
Here are a few other Shop Talk Blog posts you might find interesting:
Face Seal Basics
These seals go by several different names, all of which are correct: main seals, metal face seals, duo-cone seals, floating face seals, and floating seals. But regardless of their name, they always serve the same purpose. Here's how one of the authors at Machine Design explains face seals:
"The primary sealing interface is between rotating and stationary members that form a plane perpendicular to the shaft. The sealing area is a narrow ring where the two faces contact. One of the sealing faces is usually metal or ceramic and the other is usually graphite or plastic."
In the case of a final drive motor, a face seal is located where the hub and the axle come together. The narrow rings referred to in the definition are both precision-lapped (or ground) metal rings.
Installation
It is extremely important that face seals be installed correctly, and there are quite a few things that can go wrong during the installation. If you don't follow the installation instructions, you risk shortening the life of your face seals.
For example, damage such as gouges or scratches to the precision ground surfaces of the face seals can result in leaking. Be careful when handling the seal components, and don't unpack them until you are actually ready to install them.
This a brand new set of face seals ready for installation on a final drive motor.
It's extremely important the installation takes place in a clean work area and that your hands are clean, as well. Any dirt on the seal faces can lead to leaks! Avoid touching or handling the lapped seal faces and never seat the seals down on their faces.
Lubrication is also important:
- Always use a lubricant to prevent the o-ring from tearing or rolling
- Make sure the lubricant is compatible with the o-ring material (the wrong lubricant can cause the o-ring to weaken and possibly deteriorate)
- Only use clean, fresh lubricant
In this video, we talk about how to go about installing face seals on a Bobcat T300 final drive motor.
Working Conditions
Another key factor in the life of your face seals lies in the conditions your machine has been working in. For example, a machine doing swamp work is going to have external pressure on the seals due to be submerged underwater. That will reduce the life expectancy of the main seals, and there isn't really anything that can be done. Just recognize that the seals will need to be replaced sooner than on a machine that works on a construction site.
Undercarriage Condition
Exposure to extremely abrasive media can also lead to damaged seals, which is why it's important to clean the undercarriage of your machine on a regular basis. And that brings us to another factor that can reduce the lifespan of your face seals: dirt and debris packed around the final drive. If the undercarriage isn't cleaned on a regular basis, that debris will become more and more packed, even to the point of forcing the face seals apart.
On this final drive motor, so much hardened debris built up that the face seals were forced apart.
All you need to do is periodically use a pressure washer the clean the undercarriage. Taking the time to do this will help prevent the premature failure of these expensive seals. Just make it a part of your regular maintenance plan and you will see a difference in the condition of the undercarriage and the life of your face seals.
Conclusion
Face seals aren't cheap, and having them wear out prematurely can start to get expensive. The seals are costly, and so are the downtime and the manpower needed to get them correctly replaced. The good news is there are measures you can take to make sure the last:
- Always follow the installation instructions for these seals
- Only replace them in a clean environment
- Keep your undercarriage clean.
