DOOSAN DX800LC-7 Rock Drive Wheel/Rock Final Drive Sprocket Wheel Assembly manufactured by cqctrack

What is the Drive Wheel/Final Drive Sprocket Assembly?

This is not a single part but a major assembly that forms the “hub” of the excavator’s track system. It’s the final stage of the drivetrain that converts the hydraulic motor’s power into the rotational force that moves the tracks.

The assembly primarily consists of two integrated components:

1. Sprocket (Drive Wheel): The large, toothed wheel that meshes directly with the track links (pads). As it turns, it pulls the track around the undercarriage.
2. Final Drive: The sealed, planetary gear reduction unit bolted directly to the track frame. It takes the high-speed, low-torque rotation from the hydraulic track motor and converts it into the low-speed, high-torque rotation needed to drive the massive sprocket and move the machine.

On a machine like the DX800LC, this assembly is exceptionally large, heavy, and built to withstand immense stress.

Key Functions

• Power Transmission: It is the final mechanical point that delivers power from the engine and hydraulic system to the tracks.
• Gear Reduction: The planetary gear set inside the final drive provides massive torque multiplication, allowing the 80-ton machine to climb, push, and pivot.
• Durability: Designed to handle shock loads from digging, traveling over rough terrain, and swinging with heavy loads.

Common Problems and Failure Modes

Due to its critical role, this assembly is subject to significant wear and potential failure. Common issues include:

• Sprocket Tooth Wear: The teeth wear down over time from constant contact with the track chain. Severe wear leads to a “hooked” profile, which can cause the track to derail or jump.
• Final Drive Seal Failure: This is a very common issue. If the main seal fails, hydraulic oil leaks out, and contaminants (water, dirt, abrasive particles) get in. This leads to rapid internal wear and catastrophic failure of the gears and bearings.
• Bearing Failure: The bearings supporting the sprocket shaft can fail due to age, contamination, or misalignment, causing play, noise, and eventual seizure.
• Gear Failure: The internal planetary gears can break or wear out due to lack of lubrication (from a leak), contamination, or extreme shock loads.
• Cracking/Breakage: The sprocket or final drive housing can develop cracks from fatigue or impact damage.

Signs of a Failing Drive/Final Drive Assembly:

• Unusual grinding or knocking noises from the track area.
• Loss of power or the track “stalling” under light loads.
• The track is difficult to turn by hand (seized bearing).
• Visible oil leaks around the sprocket hub.
• Excessive play or wobble in the sprocket.

Replacement Considerations for the DX800LC

Replacing this assembly on an 80-ton excavator is a major and expensive undertaking. You have several options:

1. Genuine Doosan (Doosan Infracore) Parts

• Pros: Guaranteed to fit and perform to original specifications. Comes with a warranty and is supported by the OEM.
• Cons: Highest cost option.

2. Aftermarket/Will-Fit Replacement Assemblies

• Pros: Significant cost savings (often 30-50% less than OEM). Many reputable manufacturers produce high-quality aftermarket final drives that meet or exceed OEM specs.
• Cons: Quality can vary. It’s crucial to source from a well-known and reputable supplier.
  • Recommended Action: Look for suppliers who specialize in undercarriage and final drive components for large excavators.

3. Remanufactured/Rebuilt Assemblies

• Pros: A cost-effective and environmentally friendly option. A core unit is completely disassembled, inspected, worn parts replaced, machined, and reassembled to like-new condition.
• Cons: You typically need to exchange your old unit (core exchange). The quality depends entirely on the rebuilder’s standards.

4. Component Repair (Sprocket Only or Final Drive Rebuild)

• In some cases, if only the sprocket is worn, you can replace just the sprocket if it’s a bolted-on design (common on larger machines).
• Similarly, a specialized workshop can rebuild your existing final drive if the housing is intact.

Critical Information for Sourcing a Replacement

When ordering a replacement assembly, you must have the correct part number. This is typically determined by the machine’s Product Identification Number (PIN) or Serial Number.

Example of a potential part number format (for reference only):
A genuine Doosan part number might look something like ****

However, the exact part number is critical. It can vary based on the specific year and model version (e.g., DX800LC-7, DX800LC-5B) of your machine.

Important Recommendation:

Always replace Final Drives in Pairs. If one fails, the other on the opposite side has endured the same hours and operating conditions and is likely near the end of its life as well. Replacing both simultaneously prevents a second costly downtime event in the near future and ensures balanced performance.

Summary

The DOOSAN DX800LC Drive Wheel/Final Drive Sprocket Assy is a vital, high-stress component. Proper maintenance (regularly checking for leaks and play) is key to maximizing its lifespan. When replacement is necessary, carefully weigh the options of OEM, quality aftermarket, or remanufactured units, and always use the machine’s serial number to ensure you get the correct part.