The very best transmission option is when higher transmission reduction is required. A worm gear is similar to a helical gear with a throat reduce to improve the outer diameter of the wheel. The throat allows the worm gear to wrap completely around the threads of the worm. By cutting the threads on the worm rather than the teeth, and by adjusting the number of threads, different ratios can be accomplished with out modifying the mounting arrangement. A special feature of worm gears and worm equipment assemblies is their potential to prevent reverse rotation.