Specified pitches and sales opportunities of the worm do not allow the worm equipment to generate the worm. This is valuable when the software needs to lock the output if the software is running in the opposite course. When the helix angle is much less than 5°, the worm is self-locking. When the helix angle is higher than 10°, the worm can be pushed again. Worm and worm gear assemblies need to be mounted on vertical, non-intersecting shafts.