The swing reducer of an excavator (commonly known as the swing gearbox) is a key transmission component connecting the slewing motor to the slewing large gear ring. Its core function is to reduce speed and increase torque, driving the upper structure to rotate smoothly by 360°.

Core Structure
• Sun gear: Splined to the slewing motor to input high-speed power.
• Planet gear: 3 to 4 pieces per stage, rotates both revolutionally around the sun gear and rotationally on its own axis to transmit torque.
• Ring gear: Fixed to the housing and meshes with the planet gears.
• Planet carrier: Outputs power and drives the lower pinion (drive gear).
• Brake: Built-in wet multi-disc brake; spring-applied braking and hydraulic release to prevent slewing runaway.
• Housing and bearing: High-strength cast steel / forged steel housing, supported by heavy-duty bearings, with dustproof and leakproof performance.

Working Principle