This is a collection of images showing final drive brake systems in various stages of damage, along with a video illustrating what this type of damage can sound like. Don't let this happen to your drive motors!
Here are a few additional Shop Talk Blog posts you might find helpful:
- Autopsy: Kubota KX71-3 Final Drive
- Autopsy: Bobcat 331 Mini Excavator Final Drive (w/Video)
- Autopsy: Hy-Dash Final Drive Motor
If your final drive motor starts making strange sounds or vibrating more than usual, there's a chance it could be an issue with the brakes. And if you catch it in time, it may just be a problem with the charge pump power the brakes rather than your final drive. But if you ignore the problem, the brake assembly and brake pack in your drive motor might start looking like some of these.
Final Drive Brake Assembly
This image shows a severely damaged final drive brake assembly. Look closely and you can see the splines are basically torn up -- that kind of damage is beyond repair. This most likely resulted from a weak charge pump that wasn't able to generate the pressure needed to release the brake. The owner probably put off dealing with the problem which resulted in a totaled brake housing. And no doubt the brake pack was seriously damaged, too -- and we'll talk about what that looks like in a minute.
The brake housing shown below seems to be in pretty good shape until you look closely at the splines and the teeth on the brake pack that are visible. You can see where the teeth of the brake pack discs have been dragging along the spline, leaving marks and removing chunks of metal. No doubt this caused a significant amount of noise and/or vibration once the drive motor tried to reach full speed.
Here you can see some damaged splines from a final drive motor in much more detail. It's easy to see where the teeth were dragging, and no doubt this led to generated contamination on the hydraulic side of this drive motor. The metal from that scarring has to go somewhere. A normal brake housing should not look like this.
Final Drive Brake Pack
If you pull the brake pack from a final drive motor and it is discolored, keep in mind that
a discolored brake pack is a bad brake pack. As you can see below, these dark edges are a sign that the brake pack discs simply got too hot, which compromises the strength of the discs.
This particular brake pack even has some broken discs that you can see in more detail below. In this particular picture, you can also see that the teeth are damaged. Fortunately brake packs aren't too expensive, but brake hubs are.
Here are two sets of brakes: you should be able to guess which set is in good condition. Notice the discoloration present on the discs arranged on the right.
Of course, the brake pack will wear out over time and eventually need to be replaced. But if the charge pump isn't working right, their rate of wear will be greatly accelerated.
Preventing Damage
To prevent most of the damage seem here, it is important not to ignore the situation starts becoming weak. If your final drive has a braking system, a loss of power could be due to a weak charge pump.
Sudden noises and excessive vibration can also be a sign that the charge pump is affecting the ability of the brake to release. This video let's you hear what it can sound like.
Conclusion
First, we want to emphasize that you should not a change in performance or strange behavior related to your final drive motors. Ignoring problems only makes them more expensive to fix.
Secondly, other components can affect your final drive motors. External causes can include a weak charge pump that won't allow the breaks to release (as discussed here) or tracks that are too tight. Some basic troubleshooting can save you time and money.
