Worm Gear Drives: High Gear Ratio and Self-Locking Feature

Single-stage gear ratios can reach 10-100. Reverse self-locking is used in safety devices (such as elevator brakes). A bronze worm wheel paired with a hardened steel worm (HRC58) is a classic combination. Ground worms achieve an accuracy of ISO grade 5. Efficiency is typically 70-90%, and can be increased to 95% by optimizing the lead angle.