Specified pitches and prospects of the worm do not let the worm gear to generate the worm. This is valuable when the software wants to lock the output if the software is operating in the reverse route. When the helix angle is much less than 5°, the worm is self-locking. When the helix angle is greater than 10°, the worm can be pushed back again. Worm and worm equipment assemblies have to be mounted on vertical, non-intersecting shafts.