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Common Bobcat Mini Excavator Final Drive Motor Issues

Your Bobcat mini excavator is no doubt an integral part of your business. Whether it’s a Bobcat 331, Bobcat 337, or a Bobcat E35, it’s indispensable and reliable—sort of like a lifelong friend. However, even a best friend has to visit the doctor now and then. Regardless of the heavy equipment brand, final drives motors undergo significant wear and tear even with regular usage. Final drives, along with the boom and bucket, are arguably the most critical components of an excavator. This blog post will look at common issues that affect the Bobcat final drives in compact excavators.

A Common Bobcat Final Drive Problem: Main Bearing Failure

Nothing lasts forever, including the main bearing in your Bobcat. Yet, basic maintenance and mindfulness can help prolong the life of this vital component:
  • Check and change the final drive oil regularly. Equipment owners should change the final drive oil every 200-300 operating hours. It’s also a good idea to check the existing oil for metal flakes—an unfortunate indication that the bearing is already damaged.
  • Look for a leak in the main seal. Even the slightest loss of bearing lubricant can cause extra wear to the main bearing and the final drive motor.
Keep in mind that a worn main bearing will cause stress on the final drive motor and ultimately lead to the replacement of final drive parts or the entire motor. Also, be sure the maintenance plan for your Bobcat construction equipment includes a final drive oil check.

Simple Steps to Avoid Damaging High Pressure

Just as with the human circulatory system, high pressure is a killer of final drive motors. In the case of your Bobcat mini excavator, simple awareness of a clogged case drain filter can reduce the likelihood of fatal heavy equipment failure. This blockage is a familiar problem with Bobcat final drive motors.High pressure happens when the clogged filter causes hydraulic fluid to back up into the final drive motor. As the pressure increases, the oil seal leaks, causing the gear oil and hydraulic to mix. A dislodged or even missing cover plate, along with chewed up bearings, is a classic sign of high-pressure damage caused by a clogged case drain filter. Incorporate inspection of the case drain filter as part of your regular maintenance plan—the filter should be a bronze or copper color. A dark or dirty filter is a “clear” sign that your mini excavator needs a new filter. Better yet, get in the habit of changing this filter when you replace other filters on your Bobcat.

Bobcat 337 Leakage Issue: Behind the Sprocket

An oil leak at the back of the sprocket can happen with many track drives and travel motors, but this is a particular issue with the final drives in Bobcat 337 mini-excavators. The problem can usually be traced to one of two areas: The case drain filter becoming clogged or the oil seal's failure. An oil seal leak can lead to premature wear in your Bobcat's planetary hub. At the same, this leak creates an entry path for contaminants like dirt and sand. Ignoring this leak means a significantly damaged final drive motor is in your future.

Troubleshooting Starts Simple

While these issues are not exclusive to Bobcat heavy equipment, look for these early warning signs for problems with final drive motors:
  • Overheating
  • Unusual noise or vibration
  • Leaking seal
A regular inspection program can help reduce unexpected and expensive repairs.

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