When it comes to moving heavy loads, bulldozing structures and digging in challenging terrain, torque is the name of the game. Torque is a measurement of your machine’s ability to do work. From excavators and skid steers, to dozers and backhoes — more torque means a more powerful, capable machine.

In order to achieve the high levels of torque required in heavy equipment, modern machines use a specialized type of motor known as a final drive. Put simply, the final drive takes the high-speed output of your machine’s engine and converts it into high-torque output.

Sometimes called a travel motor, the final drive employs a unique system of gears, located in a housing that sits on or near the machine’s axle or undercarriage. This system of gears acts like a reducer, slowing the rotational speed of the engine’s output while simultaneously increasing its torque.

Although the final drive is a durable, low-maintenance component, it can have an outsized impact on your machine’s performance if it starts to fail. Therefore, it’s crucial the final drive is well-maintained and inspected often.

In this guide, we’ll go over some of the signs that may indicate your machine’s final drive is starting to fail. We’ll also cover the best ways to keep the final drive in good condition, helping you save on repair costs and eliminate unnecessary downtime.

Symptoms of a Faulty Final Drive Motor

The final drive is critical to the efficient operation of your heavy equipment. When your machine’s final drive starts to fail, you may notice any number of unusual symptoms during operation. Here are some of the most common signs your machine’s final drive needs some attention.

1. Unusual Noises. Unusual grinding, whining or clunking noises coming from the machine may indicate the final drive is failing. When bearings, gears or seals within the final drive become worn or damaged, they may begin to grind against each other, creating friction and unusual noises.
2. Reduced Power Output. If your machine is struggling to operate efficiently, is moving slowly or is showing a general loss of power, a faulty final drive may be the culprit. Worn-out gears, bearings or seals within the final drive can lead to inefficient torque transmission, resulting in a loss of power.
3. Excessive Vibration. Pronounced vibrations felt throughout the equipment while in operation may indicate a problem with the final drive motor. When gears in the final drive become damaged or imbalanced, the resulting vibrations may disperse throughout the machine’s frame.
4. Fluid Leaks. Puddles or traces of hydraulic fluid or gear oil underneath the equipment, particularly near the final drive housing, typically indicate a problem with the final drive motor. Leaking seals or gaskets within the final drive can cause hydraulic fluid or oil to escape, leading to fluid leaks.
5. Overheating. When a final drive begins to fail, your machine’s hydraulic components may become excessively hot, potentially causing damage to surrounding components. This may happen when the final drive is insufficiently lubricated due to worn-out seals, bearings or inadequate oil levels.
6. Erratic Movement. A machine that is exhibiting jerky or uneven movement, especially during turns or while navigating uneven terrain, may be experiencing issues with its final drive. Damaged or worn gears and bearings can cause irregular torque distribution, resulting in erratic, inconsistent movement.

Essential Final Drive Maintenance Tasks

While it may seem cheaper to put off final drive maintenance until a problem appears, doing so will lead to more expenses in the long run.

The better, more cost-effective strategy is to implement a preventive maintenance program that addresses the maintenance needs of the final drive and maintains its performance. Here are some critical final drive maintenance tasks that should be part of your program.

1. Inspect the Final Drive Often

The first and most critical aspect of final drive maintenance is frequent inspections. Final drive leaks are relatively common, and they can have devastating effects on your machine’s health.

Typically, final drive leaks occur when a seal cracks or corrodes. Not only do leaks lead to insufficient lubrication, they may also allow the ingress of abrasive materials (such as silica) into the final drive casing.

Once abrasive materials have entered the final drive, they can rapidly deteriorate the gears. Final drive leaks must be caught early on, so it’s best to inspect your machine for leaks at the beginning of each shift.

2. Maintain the Final Drive’s Gear Oil

The final drive contains gear oil that lubricates the gears and helps distribute heat generated during operation. A major aspect of final drive maintenance is maintaining the level of gear oil in your machine.

If the gear oil level becomes too low, the gears may begin grinding and overheating, rapidly deteriorating the components of the final drive. As a rule of thumb, the gear oil should be checked and topped off every 100 hours of operation, or about once per month.

In addition, the gear oil should be replaced entirely about once per year, depending on how heavily the machine has been used.

3. Keep the Undercarriage Clean

Keeping your machine’s undercarriage clean isn’t just good hygiene, it also helps preserve the integrity of the final drive. When dirt and debris become stuck to your machine’s undercarriage, they can corrode the seals of the final drive. Over time, corroded seals may begin to leak gear oil and allow the ingress of harmful contaminants into the final drive.

To prevent the degradation of the final drive’s seals, it’s important to keep the undercarriage clean and clear of debris. To this end, you should end each working day by spraying down the machine’s undercarriage and removing any caked-on debris, such as mud.

4. Maintain Case Drain Filters

In some machines, the final drive has a small case drain filter that is located in the low-pressure case drain. If this filter becomes clogged, the final drive’s performance may be impacted.

Check your machine’s operating manual to find out if its final drive is equipped with a case drain filter. If so, you’ll need to change this filter according to intervals recommended by the equipment manufacturer.

Final thoughts

While the final drive is a durable component capable of withstanding extreme conditions, it must be properly maintained. Implementing a preventative maintenance plan that adequately addresses the needs of your machine’s final drive is the best way to prevent breakdowns, minimize costly repairs and reduce unnecessary downtime. If your machine’s components become worn or damaged due to a malfunctioning final drive, look no further than the MechLink Shop. Our growing catalog of OEM and aftermarket heavy equipment parts has you covered. Can’t find what you’re looking for? Reach out to one of our parts experts and get personalized assistance.