What a Final Drive Is And Why Getting the Replacement Right Matters

The final drive, also called a travel motor assembly or undercarriage final drive is a hydraulic planetary gearbox mounted at the drive sprocket end of the track frame on each side of the machine. It receives high-pressure hydraulic fluid from the machine's travel circuit and uses a planetary gear reduction system to convert that hydraulic input into the low-speed, high-torque rotational output needed to drive the track.

A final drive that is leaking, noisy, or delivering reduced travel speed is not a monitor-and-manage situation. It is a replace-now situation. A final drive running with an depleted oil charge destroys its own planetary gears within hours of continued operation turning what could have been a single unit replacement into a complete final drive assembly replacement at significantly higher cost.

At Imara Engineering, when a customer contacts us with a travel problem, the first question we ask is how long the symptom has been present. The answer determines whether a single final drive unit resolves the problem or whether the travel motor needs inspecting as well.

Warning Signs, When Your Final Drive Is Failing

Final drive failure almost always gives warning before it becomes a complete breakdown. These signals across your excavator undercarriage parts demand immediate attention:

• Machine pulling to one side during travel — the most common early symptom. One final drive is underperforming relative to the other. The machine drifts even when the controls are set straight.
• Oil leaking from the drive sprocket area — final drive seal failure. The planetary gear oil charge is escaping. Every operating hour without a full oil charge accelerates internal gear wear exponentially.
• Grinding, whining, or rattling noise during travel — planetary gear wear or bearing failure inside the final drive assembly. The noise will worsen progressively until the unit seizes.
• Reduced travel speed on one or both sides — the final drive is not delivering full torque output. Hydraulic pressure loss, internal gear wear, or motor failure.
• Complete loss of drive on one side — end-stage final drive failure. The planetary gear assembly has failed and the track on that side is no longer being driven.
• Excessive heat from the drive sprocket area during operation — bearing failure or oil starvation inside the final drive. Heat is the fastest route to catastrophic gear destruction.

Final Drives by Machine Type

The correct final drive specification is determined by your machine's hydraulic system pressure, travel motor flow rate, gear reduction ratio, and mounting configuration none of which are interchangeable between machine types or brands.

Excavator Final Drives

The mid and full-size excavator final drive range covers machines from 3-tonne through to 35-tonne operating weight, a specification range that varies enormously in hydraulic pressure rating, planetary gear reduction ratio, and mounting bolt pattern. Our excavator final drive inventory is cross-referenced against OEM part numbers for Caterpillar, Komatsu, Kubota, Hitachi, Volvo, and Doosan machines. Every unit tested for pressure integrity before dispatch and supplied with a full oil charge. 

Mini Excavator Final Drives

Mini excavator final drives in the 1-tonne to 8-tonne class are compact two-stage planetary reduction units and despite their smaller size, they are among the most frequently replaced final drives in the market due to the intensive daily operating cycles of mini excavators in construction and landscaping. We stock final drives for Caterpillar, Komatsu, Kubota, Bobcat, Hitachi, Yanmar, and JCB mini excavators across all major model series. 

Skid Steer Final Drives

Skid steer and compact track loader final drives operate under a distinctly different load profile high-frequency directional cycling, counter-rotation stress, and continuous duty cycles that demand a final drive assembly built specifically for compact loader operating conditions. We stock final drives for Caterpillar, Bobcat, Takeuchi, Case, and Gehl compact track loaders and skid steers.

Bulldozer Final Drives

Bulldozer final drives carry the sustained high-load torque demands of continuous blade pushing work the most mechanically demanding final drive application in the tracked machine category. Our bulldozer final drive range covers Cat D series and Komatsu D series dozers across the most widely operated dozer weight classes. 

Final Drives by Brand

Caterpillar Final Drives

Covering the Cat 301, 302, 303, 305, and 308 mini excavator series and Cat compact track loaders. Cat final drives are among the most precisely specified units in the compact machine segment; our Cat-specification units are cross-referenced against OEM part numbers for exact hydraulic and dimensional fitment. Cat 303 final drive and Cat 305 final drive specifications are priority stock items. 

Komatsu Final Drives

Compatible with Komatsu PC15, PC20, PC35, PC50, and PC78 series mini excavators. The Komatsu PC50 final drive is one of the most commonly replaced units in the compact excavator segment stocked as a priority specification. Every unit matched to the PC series hydraulic system pressure and planetary reduction ratio. 

Kubota Final Drives

Covering the Kubota KX series including KX040, KX057, KX080, and KX121 models and the U series including U17 and U35. The Kubota KX121 final drive and Kubota U17 final drive are held in dedicated stock given the volume of these machines operating across agricultural drainage and landscaping fleets. 

Bobcat Final Drives

Stocked for the Bobcat E series including E32, E35, and E42 mini excavators and the T590 and T630 compact track loaders. The Bobcat T590 final drive and Bobcat E35 final drive are priority stock specifications given the volume of these machines across global hire and contracting fleets. 

Volvo Final Drives

Covering the Volvo EC series excavators and articulated hauler range. Volvo final drives are engineered to the precise hydraulic specifications of the Volvo construction equipment hydraulic system our Volvo-specification units are confirmed against EC series OEM part numbers for hydraulic pressure rating, reduction ratio, and mounting configuration. 

Hitachi Final Drives

Stocked for the Hitachi ZX series including ZX17, ZX26, ZX35, ZX50, ZX75, and ZX200 compact and mid-size excavators. Hitachi final drives are manufactured to the ZX series hydraulic specification confirmed against Hitachi OEM part numbers for each ZX model. Always specify the ZX model designation when ordering Hitachi undercarriage parts. 

What Every Imara Engineering Final Drive Is Tested for Before Dispatch

The final drive replacement market has significant quality variation and the consequences of fitting an under-specification unit extend to the travel motor, the sprocket, and the rubber track above it. At Imara Engineering, four checkpoints are applied to every final drive before dispatch:

• Hydraulic pressure integrity test at rated operating pressure — every unit is pressure-tested at the hydraulic rating for its specific machine specification. A unit that fails this test does not leave our facility.
• Planetary gear reduction ratio verification — confirmed against the OEM specification for each machine model and production year. Travel speed and tractive effort will match your machine's design parameters from the first operating hour.
• Seal grade confirmation — seals are verified against the operating temperature range and pressure rating for each machine family. Generic seal grades applied across all units are one of the leading causes of premature aftermarket final drive failure.
• Full oil charge and port protection for transit — every unit ships with a correct-grade oil charge fully installed and hydraulic port protectors fitted. Ready to install on arrival no preparation required before fitting.

OEM final drives carry a brand premium above equivalent aftermarket specification. At Imara Engineering, the testing standard, hydraulic rating, and fitment guarantee are the same. The premium is not.

Final Drives and the Wider Undercarriage System

The final drive does not fail in isolation and a final drive replacement is the right moment to inspect every component it has been affecting across the undercarriage system:

• Drive Sprocket — a final drive running under degraded conditions delivers uneven torque to the sprocket with every revolution. Inspect sprocket teeth for hook wear and flange damage. A damaged sprocket stresses a new final drive from the first operating hour.
• Rubber Tracks — abnormal final drive behaviour creates uneven tension and stress across the rubber track. Inspect inner surface and steel cord condition before returning the machine to operation.
• Track Adjusters — confirm correct track tension is being maintained independently of the final drive replacement. A worn adjuster puts immediate abnormal load on a new final drive from the first operating hour.
• Travel Motor — if the final drive failed due to seal degradation and hydraulic fluid shows contamination, inspect the travel motor before refitting. A new final drive exposed to contaminated fluid from a weeping travel motor seal is a repeat failure within months.

Industries That Cannot Afford Final Drive Downtime

• Construction & Civil Engineering — an excavator off-site on a construction programme has a direct, measurable daily cost. We stock the highest-volume final drive specifications precisely because construction operators cannot wait on sourcing lead times.
• Agriculture & Land Management — seasonal pressure means a broken excavator during a drainage season is not a minor inconvenience. Fast dispatch is a commercial necessity for agricultural operators.
• Landscaping & Garden Construction — one broken U17 or KX final drive on a residential project holds up an entire installation crew and a client delivery date simultaneously.
• Plant Hire & Rental Fleets — a hired machine with a failed final drive is lost hire income from the moment of breakdown. Hire operators who maintain trade accounts with Imara Engineering carry the supply security to resolve final drive failures without extended lead time exposure.
• Mining & Quarrying — large excavator and bulldozer final drives for machines in continuous high-load production cycles where final drive failure disrupts the entire downstream production chain.