Views: 0 Author: Site Editor Publish Time: 2026-07-15 Origin: Site
TL;DR:
A final drive transmission converts hydraulic motor power into the track movement that drives your excavator forward and backward. For Doosan machines like the DX220A, DX225LC, DX230LC, and DH220-7, BN Gears (Hongxiang Machinery) manufactures precision aftermarket replacements built to OEM tolerances with a 1,000-hour warranty and worldwide shipping.
Your excavator's undercarriage takes a beating every single shift. Mud, rock, water, and extreme loads cycle through the drivetrain constantly — and when a critical component fails on a job site, the cost isn't just the part. It's the crane time, the lost production, and the scramble to find a reliable replacement fast.
The final drive transmission is the component most likely to cause that kind of standstill. It's responsible for translating the high-speed, low-torque rotation of a hydraulic motor into the slow, high-torque power that actually moves your tracks. When it wears out or fails, the machine goes nowhere.
This guide covers how final drive transmissions work, what makes Doosan units unique, how to identify the right part number, and why BN Gears is a trusted supplier across Southeast Asia, the Middle East, North America, and Europe.
The final drive is the last mechanical link between your hydraulic system and the ground. It sits inside the track frame on each side of the machine, receiving rotational input from the travel motor and reducing that speed through a planetary gear set — typically two stages — before delivering torque to the sprocket that drives the tracks.
The planetary design is deliberate. Planetary gears distribute load across multiple contact points simultaneously, which allows the unit to handle the enormous forces generated during travel, slope climbing, and trench work without concentrating stress on a single gear tooth. That load-sharing is what gives a well-built final drive its durability over thousands of operating hours.
For Doosan excavators specifically, the final drive is mounted in the undercarriage's POWER TRAIN or TRAVEL MOTOR position depending on the model generation. Every component — the spindle, floating seal, carrier assemblies, sun gear, needle bearings, and shim plates — works together as a sealed, precision system. Replacing just one worn component rarely restores full performance. Full assembly replacement is almost always the correct repair decision.
Doosan produces a wide range of crawler excavators, from the compact DX220A series to heavy-duty models like the DX340 and DX520LC. These machines operate across construction, mining, and demolition environments where operating loads frequently exceed design ratings.
The Doosan final drive range must therefore meet very specific tolerances. Frame hole and sprocket hole counts vary by model, internal gear ratios differ across generations, and the motor shaft and housing configuration changes between series. A part sourced without precise model matching will either fail to install or, worse, install incorrectly and cause downstream damage to the travel motor.
Identifying failure early reduces total repair costs significantly. Watch for these symptoms:
Abnormal noise during travel — grinding, whining, or clunking sounds that change with travel speed often indicate worn planetary gears or damaged bearings
Track slippage or sluggish movement — reduced output torque can mean internal gear wear or oil leakage inside the final drive housing
Oil leakage from the final drive — a compromised floating seal allows contamination in and lubrication oil out, accelerating internal wear
Machine pulling to one side — asymmetric final drive wear causes unequal output torque across both tracks
When two or more of these symptoms appear together, a full assembly inspection is warranted. In most cases, a replacement assembly is more cost-effective than sourcing individual internal components.
BN Gears (Hongxiang Machinery Co., Ltd.) has manufactured excavator transmission components since 2000 from an 18,000 m² factory in Jiangmen, China. The manufacturing process includes heat treatment on all gear components to increase bending strength, prevent case crushing, and improve surface wear resistance — the same engineering logic used in OEM production.
Every BN final drive assembly ships complete, ready to install. The unit arrives without the travel motor attached (motor sold separately), but includes the motor shaft and motor housing pre-installed, so integration into the machine is straightforward.
Feature | BN Gears Specification |
|---|---|
Assembly condition | Complete, new, undamaged |
Motor included | No (motor shaft and housing pre-installed) |
Warranty | 1,000 working hours |
Surface finish | Painted or unpainted (per customer requirement) |
Packing | Plywood case, fumigation-free |
Delivery | Sea, air, or carrier — worldwide |
MOQ | 1 piece |
Trade terms | EXW, FOB, CFR, CIF |
Payment terms | T/T, Western Union, Escrow |
Lead time (stock) | 4–7 days processing and packing |
BN Gears currently holds high market share across Southeast Asia (65%), North and South America (10%), the Middle East (8%), and Europe (8%), with over 6,600 product parts in its catalog covering 600+ construction machinery models.
Matching the correct part number is the single most important step in sourcing a final drive. Model names alone are not sufficient — Doosan has revised specifications across generational updates, meaning a DH220-5 and a DH220-7 take different units despite the similar model designation.
The K9007404 is a prime example of how precise this matching must be. This part number applies specifically to the Doosan DX220A, DX225LC, DX230LC, and DH220-7 models, with 30 frame holes and 30 sprocket holes — specifications that must be confirmed before ordering. Using this part number on an adjacent model without verifying the hole counts and shaft configuration would result in a fitment failure.
To place an order correctly with BN Gears, customers should provide:
The excavator's full model name and serial number
The OEM part number if available (e.g., K9007404, 9208060, 9208109)
Frame hole and sprocket hole counts
Whether a painted or unpainted finish is required
Delivery terms and port of destination
BN Gears' sales team will then confirm the match and quote accordingly. For Doosan models not listed in the standard catalog, the engineering team evaluates compatibility and can develop new fits on request.
Generic aftermarket suppliers often source components from multiple sub-vendors with inconsistent quality controls. BN Gears manufactures all components in-house, using more than 80 advanced production facilities and a team of 8 senior engineers with over 30 years of design and machining experience.
That vertical integration matters in practice. It means tolerances are consistent across batches, warranty claims are handled directly by the manufacturer, and new model compatibility can be developed and validated internally rather than depending on third-party tooling.
The company is certified under ISO 9001:2015 and recognized as a China High-tech Enterprise. Long-term supply relationships with companies including Foster Wheeler Power Machinery Co., Ltd. and C.R. Dinly validate the manufacturing quality standard at a commercial scale.
For construction fleet managers sourcing Doosan final drive replacements, that combination of traceability, in-house manufacturing, and global logistics capability means fewer surprises at installation and longer service life after replacement.
A final drive transmission is the planetary reduction gearbox that converts high-speed hydraulic motor rotation into the slow, high-torque output required to drive the excavator's tracks. It mounts inside the track frame and is a critical undercarriage component.
Match by full model name and OEM part number. Key specifications to verify include the frame hole count, sprocket hole count, and motor shaft configuration. For Doosan models, part numbers like K9007404 (DX220A/DX225LC/DX230LC/DH220-7) are model-specific and should not be cross-applied without engineering confirmation.
Yes. BN Gears ships worldwide by sea, air, or carrier from Jiangmen Port. Trade terms include EXW, FOB, CFR, and CIF. In-stock orders typically process and ship within 4–7 days.
No. The assembly ships without the travel motor but includes the motor shaft and motor housing pre-installed, making installation into the machine straightforward.
BN Gears provides a 1,000 working hours warranty covering manufacturing defects. Warranty is void for damage resulting from incorrect installation, overloading, or operation beyond rated capacity.
Yes. BN Gears actively develops parts for both current and older excavator models and submits new product additions monthly. Contact the sales team with your model and serial number to confirm availability.
