Slewing drives represent a critical innovation in rotational power transmission, combining a slewing bearing with a compact gear system to handle complex load conditions. The fundamental design incorporates a worm gear system where the worm shaft engages with gear teeth cut directly into the slewing bearing's raceway. This configuration enables the transmission of high torque while supporting substantial axial, radial, and moment loads simultaneously.

The mechanical advantage stems from the high reduction ratios typically ranging from 10:1 to 500:1, allowing relatively small input forces to generate significant output torque. The worm gear geometry, particularly the lead angle and pressure angle, determines both efficiency and self-locking capability. Single-start worm designs with lead angles below 5 degrees typically provide reliable self-locking but achieve efficiencies of only 40-50%, while multi-start configurations can reach 85-90% efficiency but require external braking systems.

Modern designs employ finite element analysis (FEA) to optimize load distribution across gear teeth and bearing raceways. Advanced manufacturers use profile-shifted gear teeth and crowned worm profiles to ensure even stress distribution under moment loads exceeding 200 kN·m. The housing design incorporates strategic ribbing and optimized wall thickness to maintain structural integrity while minimizing weight.