Certain pitches and prospects of the worm do not let the worm gear to generate the worm. This is beneficial when the application needs to lock the output if the application is running in the opposite path. When the helix angle is less than 5°, the worm is self-locking. When the helix angle is greater than 10°, the worm can be pushed again. Worm and worm gear assemblies should be mounted on vertical, non-intersecting shafts.