A final drive is two machines bolted together. On one end there is a hydraulic piston motor that turns oil pressure into rotation. On the other there is a planetary gearbox that trades that speed for torque. Between them sit the bearings and seals that decide how long the whole assembly lasts. Knowing which part is which turns a vague noise into a specific answer, and it tells you whether you are looking at a seal kit or a new unit.
Open a drain plug and the oil tells you most of what you need to know. Clean oil at the right level means the seal is holding. Grey, milky oil means water ingress and a failed face seal. Fine glitter suspended in the oil means bearing or gear material is already circulating. Chunks on the magnetic plug mean the planetary set has started to break up and the housing is now full of debris that will migrate into the motor.
Sound and behaviour narrow it further. A whine that rises with travel speed points to the motor. A growl under load with the machine loaded on one track points to bearings. A clunk on direction change points to gear backlash. Put together with the checks in the seven symptoms of a failing final drive, that is usually enough to decide before anything is pulled apart.
A duo-cone seal kit and fresh gear oil are worth doing the moment the oil looks wrong and nothing metallic has appeared yet. Caught at that point, the job is a few hours and a small parts bill. Our gear oil change guide covers the intervals that keep drives in that window.
Once metal is in the oil, the calculation changes, because the bearings, the gear set and the rotating group have all been through the same debris. What that means in money, and when a full replacement is genuinely the cheaper option, is worked through in rebuild or replace a final drive motor.
When a new assembly is the answer, Hydraulic America stocks units for nearly 40 equipment brands in the final drive motors catalogue, new, shipped across the US and Canada, with coverage of up to two years depending on the item.
If the hydraulic final drive motor on your vehicle is not functioning properly, it can be a frustrating and costly problem to deal with. Fortunately, there are steps you can take to diagnose and repair the issue yourself, potentially saving you the cost of a professional repair. Here is a step-by-step guide on how to repair a hydraulic final drive motor:
Gather the necessary tools and equipment: Before you begin, you will need to gather all of the tools and equipment you will need to complete the repair. This may include a hydraulic jack, a torque wrench, a variety of sockets and wrenches, a hammer, a punch, a pry bar, and a hydraulic pump. You may also need a replacement hydraulic final drive motor, depending on the severity of the issue.
Raise and secure the vehicle: In order to access the final drive motor, you will need to raise the vehicle off the ground and secure it in place. Use a hydraulic jack to lift the vehicle and place it on stands or blocks. Be sure to engage the parking brake and chock the wheels to prevent the vehicle from moving.
Inspect the final drive motor: Once the vehicle is secure, you will need to inspect the final drive motor to determine the cause of the issue. Look for visible signs of damage, such as leaks, cracks, or broken components. You may also need to use a hydraulic pressure gauge to test the pressure of the motor and determine if it is functioning correctly.
Replace any damaged components: If you find any damaged components during your inspection, you will need to replace them. This may include the hydraulic pump, hoses, lines, or seals. Be sure to follow the instructions provided by the manufacturer when replacing these components, and make sure that they are properly installed and connected.
Test the repaired motor: Once you have replaced any damaged components, you will need to test the repaired final drive motor to make sure that it is functioning properly. Start the vehicle and test the movement of the final drive motor to ensure that it is working as it should.
Reassemble the vehicle: If the repaired final drive motor is working properly, you can reassemble the vehicle. Replace any covers or panels that you removed during the repair process, and be sure to tighten all bolts and fittings securely.
By following these steps, you should be able to repair the hydraulic final drive motor on your vehicle. However, if you are unsure of your ability to complete this repair or if you encounter any problems, it is always best to consult a professional mechanic for assistance.
The sequence for pulling a final drive is broadly the same on every tracked machine, and we set it out in the excavator final drive removal and replacement guide. What changes between machines is the part that catches people out: how the drive is mounted, how much it weighs, what has to come off first and which variant your serial number takes. Here is what differs across the machine types we supply most often, and what each one means for a final drive motor replacement.
A dozer final drive is a different job from an excavator one. The drive is a bolt-on module carrying the sprocket segments at the rear of the track frame, and on a D51 class machine the sprocket segments are usually unbolted before the drive itself, which reduces both the weight and the awkwardness of the lift. Expect the assembly to be heavier than the equivalent excavator unit and plan the lift accordingly.
Two points are specific to dozers. The track must be fully released and, on machines with sealed and lubricated track, the adjuster grease fitting has to be cracked carefully rather than opened fast. And the final drive housing on a dozer often shares oil with the sprocket hub bearing, so check the manual for the correct fill point and quantity before you refit. Getting the oil level wrong here is a common cause of a repeat failure.
On PC-series excavators the drive comes out through the outside of the track frame once the hoses are marked, capped and released. Komatsu changed travel motor specifications several times within the same model designation, so the machine serial number decides which drive you need far more reliably than the model badge does. Our Komatsu final drive motors catalogue holds 441 part numbers for exactly this reason, and the casting number on the old motor is the fastest way to land on the right one.
Compact machines look easier and often are not. The drive is lighter, but access is tight, the hoses are short, and there is rarely room to withdraw the unit without removing the track guard first. On a machine of this size it is worth dropping the track completely rather than trying to work around it.
Mini excavators also carry a small gear oil volume in a housing that runs hot, which is why they are unforgiving about maintenance intervals. Parts for these machines are listed under New Holland final drive motors.
Skid steers and CTLs load the travel circuit far harder than an excavator does, because steering is done by driving one track against the other. Drives come off from the outside with the machine safely supported, and both sides are often replaced together since they have done identical work. Caterpillar owners should start from our CAT skid steer final drive motors page, where the range is broken down machine by machine.
Lifting equipment rated for the assembly, not improvised. Caps and plugs for every hose and port you will open, ready before the first connection comes apart. Labels or tape for the lines. The correct gear oil and the fill quantity from the manual. New mounting hardware if the old bolts have been on and off before, because stretched bolts do not hold torque. And the manufacturer's procedure for your specific machine, which overrides anything general you read online, including this page.
Three of them account for most repeat failures. Hoses reconnected in the wrong order, which sends pressure where the case drain should be and destroys the new motor on the first movement. Track tension set by eye and left too tight, which loads the new bearing from the first hour. And skipping the flush after a failure that put metal into the circuit, which feeds the debris from the old drive straight into the new one. None of the three is expensive to avoid and all three are expensive to repeat.
Confirm the drive is actually the fault, using the symptoms of a failing final drive, and check the economics in rebuild or replace a final drive motor. When you are ready, the full range for nearly 40 brands is in the final drive motors catalogue, new units, shipped across the contiguous United States and Canada, most dispatched the same day.
Hydraulic final drive motors are a key component in the drivetrain of many vehicles, providing the rotational power needed to drive the wheels. However, like any mechanical device, these motors can sometimes fail due to a variety of causes. Here are some common reasons why hydraulic final drive motors may fail:
By understanding these common causes of failure, vehicle owners and operators can take steps to prevent or mitigate the risk of hydraulic final drive motor failure. This may include proper maintenance, such as regularly checking and changing the hydraulic fluid and ensuring that the motor is properly lubricated, as well as avoiding operating the motor outside of its recommended temperature range.
A hydraulic final drive motor is a type of motor that uses hydraulic fluid to transmit power and torque from the source to the drive mechanism. It is a key component in a hydraulic system, and it is used in a wide range of applications, including construction equipment, agricultural machinery, and material handling equipment.
Hydraulic final drive motors work by using pressure to move the fluid through the system, and this pressure is generated by a pump. The fluid is then directed to the final drive motor, where it is used to transmit power and torque to the drive mechanism. The final drive motor converts the hydraulic energy into mechanical energy, which is then used to power the equipment.
There are several different types of hydraulic final drive motors, including axial piston motors, radial piston motors, and gerotor motors. Each type has its own unique set of characteristics and benefits, and the most appropriate type will depend on the specific needs of the application.
Axial piston motors are a type of hydraulic final drive motor that uses a set of pistons arranged in a circular pattern to transmit power and torque. They are highly efficient and have a high power-to-weight ratio, making them ideal for use in high-performance applications. They are also relatively simple in design and easy to maintain.
Radial piston motors are another type of hydraulic final drive motor that uses a set of pistons arranged in a circular pattern to transmit power and torque. They are highly efficient and have a high power-to-weight ratio, making them ideal for use in high-performance applications. They are also relatively simple in design and easy to maintain.
Gerotor motors are a type of hydraulic final drive motor that uses a set of gears to transmit power and torque. They are highly efficient and have a high power-to-weight ratio, making them ideal for use in high-performance applications. They are also relatively simple in design and easy to maintain.
The performance and efficiency of a hydraulic final drive motor depend on several factors, including the type of motor, the design and materials used, and the operating conditions. Some of the key performance characteristics of a hydraulic final drive motor include torque, power, efficiency, and speed.
Torque is a measure of the rotational force that the motor can generate, and it is an important factor in determining the acceleration and pulling power of the equipment. Power is a measure of the rate at which work is done, and it is usually expressed in watts or horsepower. Efficiency is a measure of the amount of hydraulic energy that is converted into mechanical energy, and it is usually expressed as a percentage. Speed is a measure of the rotational speed of the motor, and it is usually expressed in revolutions per minute (RPM).
There are several factors that can affect the performance and efficiency of a hydraulic final drive motor, including the load on the motor, the temperature of the fluid, and the operating conditions. The load on the motor refers to the amount of force that the motor has to overcome to move the equipment, and it can vary depending on the terrain, the weight of the equipment, and the acceleration and deceleration of the equipment. The temperature of the fluid can also affect the performance and efficiency of the motor, as excessive heat can cause the fluid to break down and reduce its efficiency. The operating conditions, such as the humidity, altitude, and air quality, can also affect the performance and efficiency of the motor.
In conclusion, a hydraulic final drive motor is a key component in a hydraulic system, and it is used to transmit power and torque from the source to the drive mechanism. There are several different types of hydraulic final drive motors, including axial piston motors, radial piston motors, and gerotor motors, each with its its own unique set of characteristics and benefits.
If you’ve spent much time around people in the heavy equipment industry, you’ve probably heard a lot of different terms used to describe a final drive motor for an excavator. You’ve probably also heard a number of different terms used for a backfill blade, since it also gets called a dozer blade, and if you’re newer to the industry, you’ve likely been part of conversations that felt like they were taking place in a foreign language.
Heavy equipment can be like that. Here at Mini Final Drives, we regularly hear about a half a dozen different names for the final drives we sell. It doesn’t phase us, because we’ve been in the heavy machinery business for over 50 years, and we’re fluent in the language of excavators and other heavy machinery.
Whether you’re new to this space, or you’ve been in it for decades like we have, it can be helpful to know what others might call that thing you call a dipper. Here’s a glossary of sorts, in no particular order, and occasional further explanation about how some terms came about.
Final Drive Motor. As a complete unit, an excavator final drive motor provides the power to turn the tracks and move the excavator. Simply stated, it is composed of two primary components that are sealed and joined together – the first is the hydraulic “motor” that receives energy from the main hydraulic pump. The second part is the gearbox, which is called the “final drive,” because it is, as stated in the Google dictionary, “the last (final) part of the transmission system...”
The hydraulic motor is the part of your final drive motor to which the hydraulic hoses connect. Most people simply call this portion the “motor,” but terms like travel motor and propel motor, also appear in the industry. Interestingly, a lot of people mistakenly see the hoses on the back side of a final drive motor and think it is a hydraulic pump, but it is not. The central pump is located elsewhere on the excavator and supplies the hydraulic power to turn that final drive motor.
So what is the final drive? The final drive is the planetary gearbox that protrudes through the track sprocket and contains a couple gear oil fill/drain plugs (see our other articles about the importance of maintaining that gear oil!). In our experience, 90% of people in the heavy equipment industry simply use the term "final drive" to describe a final drive motor, but technically the "final drive" is only the gearbox portion, which would, of course, not work without the hydraulic motor to supply the rotational power. Due to the relatively high cost of parts and labor to join these two sections, mini and midi excavator final drives and travel motors are rarely sold separately because it isn't cost practical (unlike on much larger machines where it is more economical), so you will likely need to replace both portions with a complete, new, pre-assembled unit when either reach end of life.
Other slang terms for a final drive motor have cropped up in the industry, such as walking motor, track drive, and track motor. As they say, “a rose by any other name is still but a rose,” and that’s true for all the various terms you may have for a final drive motor and its components.
Grousers. Your excavator or dozer’s tracks need good traction in order to operate in most conditions. Grousers are the protruding portions on an excavator’s track that rise up like zipper teeth. They increase traction. They also sometimes get referred to as cleats, and if you’ve ever played soccer, football, baseball, or golf, you understand why.
Maximum Bucket Force. Also called maximum or max digging force, the maximum bucket force is the amount of force that can be utilized in digging with an excavator’s bucket. It should not be confused with the maximum crowd force, or breakout force, which refers to the excavator arm and the amount of force it’s able to use to “break out” the load.
The Boom and The Arm. The angled arm on your excavator is called the boom, and the piece that’s pinned to the boom is called the arm. Boom as a term, is pretty universal, except for knuckle booms, which can move to the right or left. The arm can also be referred to as the stick or the dipper. How far an excavator’s arm can extend is referred to as its reach.
Ground Clearance. Ground clearance refers to the space between the machine’s undercarriage and the ground, between the treads. If you’re operating a piece of heavy machinery, keeping your ground clearance in mind is an essential part of doing your job well, so you don’t get high-centered, stuck, and risk damaging your machine and losing time.
House. The house isn’t just the cab that sits on top of the undercarriage where the operator “lives.” When people in the heavy machinery industry refer to the house, they mean the cab, the fuel tank, counterweights, the hydraulic tank, and the engine.
Counterweights. Counterweights, depending on the age of the excavator you’re working with, can be made out of cast iron, lead, concrete, cast steel, you name it. They provide a “counterweight” to the load, balancing it and making it more stable, which also uses less energy and causes less stress for the machine.
Swamp pad. Also called a swamp mat and a wetland mat, a swamp pad is a large, usually wooden pad placed underneath the tracks on a dozer or excavator anytime the ground is soft, often from water. It works by spreading out the machine’s weight so the tracks don’t sink into the ground and get stuck. Rubber Duck. Known more often as a wheel excavator, a rubber duck is just an excavator that has wheels instead of tracks. The origin of the slang term rubber duck is disputed. Some say it refers only to the rubber wheels, while others claim it’s a reference to how the wheel excavator wobbles back and forth on certain ground conditions, kind of like a rubber duck in the bath.
At MiniFinalDrives, we don’t care what you call it, especially when it comes to final drives. If you call us and tell us you need a "track drive motor for a Kubota KX91-3 mini excavator", we know exactly what you mean and what you need, which is a complete final drive and travel motor for the Kubota KX91-3, fully assembled and ready to install! Just give us a call to chat - we’re always glad to help you find the right final drive motor solution to keep your machine moving! And if you have any questions about heavy equipment vocabulary, we’re glad to help out with that too.
Our family at Mini Final Drives has been providing excellent Quality, Value, and Service for over 50 years, and you can continue to count on us for a lifetime of friendly, helpful support for all your final drive and travel motor needs. Call us today at 877-483-2806 or visit our online store at www.minifinaldrives.com to find and order what you need today for Fast and Free delivery to your door.
