The Swing Reduction (also called Swing Gearbox, Swing Reducer, or Swing Drive) is a critical transmission component in the swing system of crawler excavators.
It transfers and converts the torque from the swing motor into a lower speed and higher torque output to rotate the upper structure of the excavator smoothly and reliably.
31NB-11150/31NB-11151
These models are genuine or replacement parts designed for Hyundai R450LC-7 and Hyundai R500LC-7 excavators.
Depending on the equipment configuration, both models may be interchangeable or functionally paired within the same swing drive system.
Hyundai R450LC-7 / R450LC-7A
Hyundai R500LC-7 / R500LC-7A
Some references also list compatibility with RD510LC-7 (verify with serial number and parts diagram before purchase).
| Item | Description |
| Structure Type | Planetary gear reduction system with internal ring gear |
| Gear Ratio | High reduction ratio providing stable, high-torque swing motion |
| Material | High-strength alloy steel with carburizing and quenching treatment for superior hardness and wear resistance |
| Sealing System | Multi-layer oil seal and mechanical seal combination for excellent leakage protection |
| Bearing Support | Heavy-duty roller or tapered bearings for high radial and axial load capacity |
| Lubrication | Splash or forced lubrication with high-quality gear oil |
| Operating Torque Range | High-torque output suitable for 45–50 ton excavators |
| Weight | Typically several hundred kilograms (varies by version) |
Efficient torque transmission ensures stable swing motion even under heavy load conditions.
Gears and shafts are precision-machined and heat-treated for outstanding durability and fatigue resistance.
Designed to prevent oil leakage and protect against mud, dust, and water intrusion.
The modular assembly structure allows convenient disassembly, inspection, and replacement of internal parts.
100% fitting replacement for Hyundai R450LC-7 / R500LC-7 swing reduction units.
Widely available through global suppliers and distributors of Hyundai construction parts.
In the excavator swing system, the Swing Reduction Unit works together with:
Hydraulic swing motor (input power source)
Coupling or intermediate shaft
Swing ring gear (slewing ring)
Upper-frame support bearings
Sealing and lubrication systems
It converts hydraulic power from the swing motor into mechanical rotational motion that turns the upper structure of the excavator.
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