Custom Internal Gear Ring for Large Planetary Systems

Internal gears—teeth cut on the inside of a cylindrical ring—serve in planetary gear systems, ring gear drives, and slewing bearings across mining, construction, and heavy industry. Their internal mesh geometry creates unique manufacturing challenges: tool access is restricted, chip evacuation is difficult, and inspection requires specialized equipment. Few manufacturers have the capability to produce large, high-precision internal gears reliably.

Hanwei is one of them. We manufacture internal gears up to 16 m in diameter, making us one of the very few suppliers worldwide capable of handling the largest planetary and ring-gear applications. Our internal gear hobbing and shaping machines, combined with our large-capacity grinding equipment, produce tooth profiles to DIN Grade 6 accuracy even at extreme diameters.

For planetary gear sets used in mining shovel and crane slewing drives, we match the internal ring gear with the corresponding planet and sun gears, ensuring correct mesh geometry across the full set. This integrated supply approach eliminates the compatibility problems that arise when ring gears and planet gears come from different manufacturers. Our four material-process routes apply equally to internal gears: cast, forged, cast-forged welded, and forged-steel-plate welded. For large slewing rings, the forged-welded construction delivers superior fatigue performance in the tooth zone while maintaining cost efficiency on the body. When replacing an internal gear in an existing assembly, our reverse-engineering service captures the complete geometry—including root diameter, tooth thickness, and helix angle—from the worn component, producing a fully interchangeable replacement.

Warranty: 1 year standard, up to 10 years for forged-welded internal rings. Request a technical consultation today.