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Help with Final Drive Leaks

Excavator final drive issues may arise from time to time, with one of the most common issues being a leak. A leak can be an indicator of a larger problem that can lead to significant and expensive repairs if it’s ignored.

Today’s article will take a look at some of the most common final drive leak situations to make the troubleshooting process more manageable, reducing the likelihood of a costly correction down the road.

Identify the Source of the Leak

Final drive motor leak identification begins by finding the source of the leak. In most cases, a leak will be one of two things: Hydraulic fluid or gear oil. When you can identify the type of fluid that’s leaking from the final drive, it will become easier to make a fix.

We’ll take a look at some of the best ways to identify the kind of fluid that’s leaking below.

Signs of a Hydraulic Fluid Leak

Hydraulic fluid has a consistency that’s similar to brake fluid but thinner than gear oil. If you see a large volume of leaked liquid, chances are that it's hydraulic fluid.

One of the first places to check for a hydraulic fluid leak is a clogged case drain filter. A leak from the filter can cause increased pressure in the case drain line. Cleaning or replacing the filter will usually get things back to normal. We’ll take a look at what it takes to clean the filter a little later on, but for now, just remember that it’s important to do!

A weak final drive motor can also be an indicator that there are reduced fluid levels. A loose or deteriorated hose or connecting adapters or sealing rings may be the leak source, as could another defect in the hydraulic system.

Signs of a Gear Oil Leak

A thick fluid leaking from the planetary side of the final drive motor is likely to be gear oil. The constant need to refill or top off the gear oil level is another indicator that you’ve got a gear oil leak in the final drive.

You can also identify a gear oil leak by checking for fluid that's dripping on the tracks or behind the sprocket. If this is the case, you might be dealing with a leaking main seal, which also goes by the names lifetime seal, floating face seal, mechanical face seal, or duo-cone seal. To prevent damage to the final drive, a leaking main seal should be replaced as soon as possible.

Other Places to Check for Gear Oil Leaks

If gear oil is leaking from the gearbox cover, check to see if the cover or casing has been damaged. In this situation, replacing the cover O-ring should solve the problem. If the issue doesn't go away, then the gearbox cover itself likely needs to be replaced. Alternatively, the gear hub casing might need machining to correct the defect. Always make sure that the oil drain plugs and their sealing O-rings are in good condition and tight, as they can be a source of leaks.

When there is a leak from behind the sprocket and the gearbox cover on excavators, it’s a sign of a critical issue. A pressure build-up in the gearbox could be causing this leak. If you notice this type of problem, take your equipment in for evaluation by a professional who can identify the leak's source.

Gear Oil Level That’s Too High

Instead of having a leak, you may have the opposite problem. An elevated gear oil level may mean that hydraulic fluid is leaking into the gearbox. This situation can result from a defective oil seal or bearings, which should be replaced right away to avoid damage to the final drive motor. Also, make sure that your serviceperson doesn't overfill your gearbox during service - final drives should only be filled to the halfway point of the cover plate using either the center fill level plug or a side mounted plug at the 3 o'clock or 9 o'clock position.

Check Your Case Drain Filter

As you check your gear oil, it may also be a good time to take a look at the case drain filter. A clogged filter can cause increased pressure in the case drain line, leading to a blown oil seal. In turn, this will cause high-pressure hydraulic fluid to enter the gearbox, potentially causing damage to the final drive. Check the case drain filter as recommended by the manufacturer of your equipment.

Essential Steps to Protect Your Final Drive

Some simple preventative measures can reduce the chances for fluid leaks to become devastating. By following these steps, you can increase the lifespan of your travel motor:

Establish a regular maintenance program that includes checking the gear oil after every 200 hours of equipment use and having an annual gear oil change (more frequently, if needed).

Perform a regular weekly visual inspection of excavators and other equipment to check for leaks and other defects.

When it’s practical, keep the equipment clean to identify final drive fluid leaks more easily.

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