Planetary & cycloidal (RV) reducers
Robust gearboxes for high-torque joints: low-ratio planetary for dynamic legs, RV/cycloidal for stiff, heavy-load axes.
Data updated
Why it matters
Low-ratio (6-10:1) planetary gearboxes enable quasi-direct-drive (QDD) joints that are back-drivable and shock-tolerant, which suits legs and dynamic locomotion (Unitree-style). RV/cycloidal reducers offer high torque and stiffness for hips and waists and are standard in industrial arms.
Why it is a bottleneck. Fewer humanoid-specific bottlenecks than harmonic reducers, but RV reducers are dominated by Nabtesco (Japan) while Chinese alternatives gain share. QDD designs shift cost to larger, more torque-dense motors.
Suppliers 3 Limited data: Few public sources for this category's figures. Supplier details are cited on each card.
Limited data. Market-share figures for RV reducers are directional only.
- NabtescoRV and RV-N cycloidal gearboxes
- Schaeffler (incl. Ewellix)Integrated rotary actuators (60-250 N·m: planetary gearbox, motor, encoder, controller); planetary roller screws; bearings
- Zhejiang Shuanghuan DrivelinePrecision gears; RV reducers (via Huandong)
Sources for this category
- Chinese RV reducers vs Nabtesco (China Robotics Insider) (Sep 16, 2026)
- RV cycloidal gearbox (Nabtesco) (accessed Oct 8, 2026)
- Who builds the joints? The humanoid actuator supplier landscape in 2026 (humanoid.guide) (Sep 16, 2026)