Specified pitches and leads of the worm do not allow the worm equipment to drive the worm. This is beneficial when the software needs to lock the output if the software is operating in the opposite path. When the helix angle is considerably less than 5°, the worm is self-locking. When the helix angle is better than 10°, the worm can be driven back again. Worm and worm equipment assemblies should be mounted on vertical, non-intersecting shafts.