Helical gears are defined by their unique design with angled cuts at the edge of the gear. They reduce friction, heat and noise exceptionally well in comparison to other types of gears. Each gear tooth is designed to interlock with the teeth of the opposing helical gear, which rotates in the opposite direction.

The design of helical gears involves determining the pitch diameter, module, pressure angle, helix angle, addendum, dedendum, and backlash. These factors are dependent on the desired gear ratio, power transmission requirements, and the design of the mechanical system.