Hardware

Worm Gear

A worm gear is a transmission that meshes a screw-like worm with a toothed wheel on a perpendicular axis, achieving high reduction ratios in a single compact stage. Sliding contact makes it less efficient than involute gearing, and at high ratios it self-locks, meaning the output cannot backdrive the input, so the joint holds position without motor power or brakes.

Why it matters for physical AI

Self-locking joints hold loads unpowered, which benefits gravity-loaded axes and fail-safe designs, but the resulting non-backdrivability blocks torque transparency, making worm-geared joints poorly suited to compliant, contact-rich learned control.