The greatest transmission option is when large transmission reduction is required. A worm gear is equivalent to a helical equipment with a throat minimize to increase the outer diameter of the wheel. The throat allows the worm gear to wrap totally about the threads of the worm. By reducing the threads on the worm relatively than the enamel, and by modifying the amount of threads, diverse ratios can be reached without modifying the mounting arrangement. A exclusive function of worm gears and worm equipment assemblies is their potential to prevent reverse rotation.