The greatest transmission choice is when higher transmission reduction is essential. A worm equipment is similar to a helical equipment with a throat lower to improve the outer diameter of the wheel. The throat permits the worm gear to wrap fully close to the threads of the worm. By cutting the threads on the worm rather than the teeth, and by changing the amount of threads, diverse ratios can be reached with out altering the mounting arrangement. A unique attribute of worm gears and worm gear assemblies is their potential to avert reverse rotation.