The best transmission selection is when large transmission reduction is needed. A worm equipment is comparable to a helical equipment with a throat minimize to increase the outer diameter of the wheel. The throat enables the worm gear to wrap completely about the threads of the worm. By chopping the threads on the worm fairly than the enamel, and by changing the amount of threads, different ratios can be accomplished with out changing the mounting arrangement. A special feature of worm gears and worm equipment assemblies is their capacity to stop reverse rotation.