Specific pitches and prospects of the worm do not enable the worm equipment to push the worm. This is valuable when the application requirements to lock the output if the application is running in the opposite direction. When the helix angle is considerably less than 5°, the worm is self-locking. When the helix angle is greater than 10°, the worm can be pushed back. Worm and worm equipment assemblies should be mounted on vertical, non-intersecting shafts.